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/gcLocker.inline.hpp" 34 #include "gc/shared/gcTrace.hpp" 35 #include "gc/shared/gcTraceTime.hpp" 36 #include "gc/shared/genCollectedHeap.hpp" 37 #include "gc/shared/genOopClosures.inline.hpp" 38 #include "gc/shared/generationSpec.hpp" 39 #include "gc/shared/space.hpp" 40 #include "gc/shared/strongRootsScope.hpp" 41 #include "gc/shared/vmGCOperations.hpp" 42 #include "gc/shared/workgroup.hpp" 43 #include "memory/filemap.hpp" 44 #include "memory/resourceArea.hpp" 45 #include "oops/oop.inline.hpp" 46 #include "runtime/biasedLocking.hpp" 47 #include "runtime/fprofiler.hpp" 48 #include "runtime/handles.hpp" 49 #include "runtime/handles.inline.hpp" 50 #include "runtime/java.hpp" 51 #include "runtime/vmThread.hpp" 52 #include "services/management.hpp" 53 #include "services/memoryService.hpp" 54 #include "utilities/macros.hpp" 55 #include "utilities/stack.inline.hpp" 56 #include "utilities/vmError.hpp" 57 #if INCLUDE_ALL_GCS 58 #include "gc/cms/concurrentMarkSweepThread.hpp" 59 #include "gc/cms/vmCMSOperations.hpp" 60 #endif // INCLUDE_ALL_GCS 61 62 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;) 63 64 // The set of potentially parallel tasks in root scanning. 65 enum GCH_strong_roots_tasks { 66 GCH_PS_Universe_oops_do, 67 GCH_PS_JNIHandles_oops_do, 68 GCH_PS_ObjectSynchronizer_oops_do, 69 GCH_PS_FlatProfiler_oops_do, 70 GCH_PS_Management_oops_do, 71 GCH_PS_SystemDictionary_oops_do, 72 GCH_PS_ClassLoaderDataGraph_oops_do, 73 GCH_PS_jvmti_oops_do, 74 GCH_PS_CodeCache_oops_do, 75 GCH_PS_younger_gens, 76 // Leave this one last. 77 GCH_PS_NumElements 78 }; 79 80 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) : 81 CollectedHeap(), 82 _rem_set(NULL), 83 _gen_policy(policy), 84 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)), 85 _full_collections_completed(0) 86 { 87 assert(policy != NULL, "Sanity check"); 88 if (UseConcMarkSweepGC) { 89 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads, 90 /* are_GC_task_threads */true, 91 /* are_ConcurrentGC_threads */false); 92 _workers->initialize_workers(); 93 } else { 94 // Serial GC does not use workers. 95 _workers = NULL; 96 } 97 } 98 99 jint GenCollectedHeap::initialize() { 100 CollectedHeap::pre_initialize(); 101 102 // While there are no constraints in the GC code that HeapWordSize 103 // be any particular value, there are multiple other areas in the 104 // system which believe this to be true (e.g. oop->object_size in some 105 // cases incorrectly returns the size in wordSize units rather than 106 // HeapWordSize). 107 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 108 109 // Allocate space for the heap. 110 111 char* heap_address; 112 ReservedSpace heap_rs; 113 114 size_t heap_alignment = collector_policy()->heap_alignment(); 115 116 heap_address = allocate(heap_alignment, &heap_rs); 117 118 if (!heap_rs.is_reserved()) { 119 vm_shutdown_during_initialization( 120 "Could not reserve enough space for object heap"); 121 return JNI_ENOMEM; 122 } 123 124 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 125 126 _rem_set = collector_policy()->create_rem_set(reserved_region()); 127 set_barrier_set(rem_set()->bs()); 128 129 ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false); 130 _young_gen = gen_policy()->young_gen_spec()->init(young_rs, 0, rem_set()); 131 heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size()); 132 133 ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false); 134 _old_gen = gen_policy()->old_gen_spec()->init(old_rs, 1, rem_set()); 135 clear_incremental_collection_failed(); 136 137 #if INCLUDE_ALL_GCS 138 // If we are running CMS, create the collector responsible 139 // for collecting the CMS generations. 140 if (collector_policy()->is_concurrent_mark_sweep_policy()) { 141 bool success = create_cms_collector(); 142 if (!success) return JNI_ENOMEM; 143 } 144 #endif // INCLUDE_ALL_GCS 145 146 return JNI_OK; 147 } 148 149 char* GenCollectedHeap::allocate(size_t alignment, 150 ReservedSpace* heap_rs){ 151 // Now figure out the total size. 152 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size(); 153 assert(alignment % pageSize == 0, "Must be"); 154 155 GenerationSpec* young_spec = gen_policy()->young_gen_spec(); 156 GenerationSpec* old_spec = gen_policy()->old_gen_spec(); 157 158 // Check for overflow. 159 size_t total_reserved = young_spec->max_size() + old_spec->max_size(); 160 if (total_reserved < young_spec->max_size()) { 161 vm_exit_during_initialization("The size of the object heap + VM data exceeds " 162 "the maximum representable size"); 163 } 164 assert(total_reserved % alignment == 0, 165 err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment=" 166 SIZE_FORMAT, total_reserved, alignment)); 167 168 *heap_rs = Universe::reserve_heap(total_reserved, alignment); 169 return heap_rs->base(); 170 } 171 172 void GenCollectedHeap::post_initialize() { 173 CollectedHeap::post_initialize(); 174 ref_processing_init(); 175 GenCollectorPolicy *policy = (GenCollectorPolicy *)collector_policy(); 176 guarantee(policy->is_generation_policy(), "Illegal policy type"); 177 assert((_young_gen->kind() == Generation::DefNew) || 178 (_young_gen->kind() == Generation::ParNew), 179 "Wrong youngest generation type"); 180 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen; 181 182 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep || 183 _old_gen->kind() == Generation::MarkSweepCompact, 184 "Wrong generation kind"); 185 186 policy->initialize_size_policy(def_new_gen->eden()->capacity(), 187 _old_gen->capacity(), 188 def_new_gen->from()->capacity()); 189 policy->initialize_gc_policy_counters(); 190 } 191 192 void GenCollectedHeap::ref_processing_init() { 193 _young_gen->ref_processor_init(); 194 _old_gen->ref_processor_init(); 195 } 196 197 size_t GenCollectedHeap::capacity() const { 198 return _young_gen->capacity() + _old_gen->capacity(); 199 } 200 201 size_t GenCollectedHeap::used() const { 202 return _young_gen->used() + _old_gen->used(); 203 } 204 205 // Save the "used_region" for generations level and lower. 206 void GenCollectedHeap::save_used_regions(int level) { 207 assert(level == 0 || level == 1, "Illegal level parameter"); 208 if (level == 1) { 209 _old_gen->save_used_region(); 210 } 211 _young_gen->save_used_region(); 212 } 213 214 size_t GenCollectedHeap::max_capacity() const { 215 return _young_gen->max_capacity() + _old_gen->max_capacity(); 216 } 217 218 // Update the _full_collections_completed counter 219 // at the end of a stop-world full GC. 220 unsigned int GenCollectedHeap::update_full_collections_completed() { 221 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 222 assert(_full_collections_completed <= _total_full_collections, 223 "Can't complete more collections than were started"); 224 _full_collections_completed = _total_full_collections; 225 ml.notify_all(); 226 return _full_collections_completed; 227 } 228 229 // Update the _full_collections_completed counter, as appropriate, 230 // at the end of a concurrent GC cycle. Note the conditional update 231 // below to allow this method to be called by a concurrent collector 232 // without synchronizing in any manner with the VM thread (which 233 // may already have initiated a STW full collection "concurrently"). 234 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) { 235 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 236 assert((_full_collections_completed <= _total_full_collections) && 237 (count <= _total_full_collections), 238 "Can't complete more collections than were started"); 239 if (count > _full_collections_completed) { 240 _full_collections_completed = count; 241 ml.notify_all(); 242 } 243 return _full_collections_completed; 244 } 245 246 247 #ifndef PRODUCT 248 // Override of memory state checking method in CollectedHeap: 249 // Some collectors (CMS for example) can't have badHeapWordVal written 250 // in the first two words of an object. (For instance , in the case of 251 // CMS these words hold state used to synchronize between certain 252 // (concurrent) GC steps and direct allocating mutators.) 253 // The skip_header_HeapWords() method below, allows us to skip 254 // over the requisite number of HeapWord's. Note that (for 255 // generational collectors) this means that those many words are 256 // skipped in each object, irrespective of the generation in which 257 // that object lives. The resultant loss of precision seems to be 258 // harmless and the pain of avoiding that imprecision appears somewhat 259 // higher than we are prepared to pay for such rudimentary debugging 260 // support. 261 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, 262 size_t size) { 263 if (CheckMemoryInitialization && ZapUnusedHeapArea) { 264 // We are asked to check a size in HeapWords, 265 // but the memory is mangled in juint words. 266 juint* start = (juint*) (addr + skip_header_HeapWords()); 267 juint* end = (juint*) (addr + size); 268 for (juint* slot = start; slot < end; slot += 1) { 269 assert(*slot == badHeapWordVal, 270 "Found non badHeapWordValue in pre-allocation check"); 271 } 272 } 273 } 274 #endif 275 276 HeapWord* GenCollectedHeap::attempt_allocation(size_t size, 277 bool is_tlab, 278 bool first_only) { 279 HeapWord* res = NULL; 280 281 if (_young_gen->should_allocate(size, is_tlab)) { 282 res = _young_gen->allocate(size, is_tlab); 283 if (res != NULL || first_only) { 284 return res; 285 } 286 } 287 288 if (_old_gen->should_allocate(size, is_tlab)) { 289 res = _old_gen->allocate(size, is_tlab); 290 } 291 292 return res; 293 } 294 295 HeapWord* GenCollectedHeap::mem_allocate(size_t size, 296 bool* gc_overhead_limit_was_exceeded) { 297 return collector_policy()->mem_allocate_work(size, 298 false /* is_tlab */, 299 gc_overhead_limit_was_exceeded); 300 } 301 302 bool GenCollectedHeap::must_clear_all_soft_refs() { 303 return _gc_cause == GCCause::_last_ditch_collection; 304 } 305 306 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 307 if (!UseConcMarkSweepGC) { 308 return false; 309 } 310 311 switch (cause) { 312 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 313 case GCCause::_java_lang_system_gc: 314 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 315 default: return false; 316 } 317 } 318 319 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size, 320 bool is_tlab, bool run_verification, bool clear_soft_refs, 321 bool restore_marks_for_biased_locking) { 322 // Timer for individual generations. Last argument is false: no CR 323 // FIXME: We should try to start the timing earlier to cover more of the GC pause 324 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later 325 // so we can assume here that the next GC id is what we want. 326 GCTraceTime t1(gen->short_name(), PrintGCDetails, false, NULL, GCId::peek()); 327 TraceCollectorStats tcs(gen->counters()); 328 TraceMemoryManagerStats tmms(gen->kind(),gc_cause()); 329 330 size_t prev_used = gen->used(); 331 gen->stat_record()->invocations++; 332 gen->stat_record()->accumulated_time.start(); 333 334 // Must be done anew before each collection because 335 // a previous collection will do mangling and will 336 // change top of some spaces. 337 record_gen_tops_before_GC(); 338 339 if (PrintGC && Verbose) { 340 gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT, 341 gen->level(), 342 gen->stat_record()->invocations, 343 size * HeapWordSize); 344 } 345 346 if (run_verification && VerifyBeforeGC) { 347 HandleMark hm; // Discard invalid handles created during verification 348 Universe::verify(" VerifyBeforeGC:"); 349 } 350 COMPILER2_PRESENT(DerivedPointerTable::clear()); 351 352 if (restore_marks_for_biased_locking) { 353 // We perform this mark word preservation work lazily 354 // because it's only at this point that we know whether we 355 // absolutely have to do it; we want to avoid doing it for 356 // scavenge-only collections where it's unnecessary 357 BiasedLocking::preserve_marks(); 358 } 359 360 // Do collection work 361 { 362 // Note on ref discovery: For what appear to be historical reasons, 363 // GCH enables and disabled (by enqueing) refs discovery. 364 // In the future this should be moved into the generation's 365 // collect method so that ref discovery and enqueueing concerns 366 // are local to a generation. The collect method could return 367 // an appropriate indication in the case that notification on 368 // the ref lock was needed. This will make the treatment of 369 // weak refs more uniform (and indeed remove such concerns 370 // from GCH). XXX 371 372 HandleMark hm; // Discard invalid handles created during gc 373 save_marks(); // save marks for all gens 374 // We want to discover references, but not process them yet. 375 // This mode is disabled in process_discovered_references if the 376 // generation does some collection work, or in 377 // enqueue_discovered_references if the generation returns 378 // without doing any work. 379 ReferenceProcessor* rp = gen->ref_processor(); 380 // If the discovery of ("weak") refs in this generation is 381 // atomic wrt other collectors in this configuration, we 382 // are guaranteed to have empty discovered ref lists. 383 if (rp->discovery_is_atomic()) { 384 rp->enable_discovery(); 385 rp->setup_policy(clear_soft_refs); 386 } else { 387 // collect() below will enable discovery as appropriate 388 } 389 gen->collect(full, clear_soft_refs, size, is_tlab); 390 if (!rp->enqueuing_is_done()) { 391 rp->enqueue_discovered_references(); 392 } else { 393 rp->set_enqueuing_is_done(false); 394 } 395 rp->verify_no_references_recorded(); 396 } 397 398 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 399 400 gen->stat_record()->accumulated_time.stop(); 401 402 update_gc_stats(gen->level(), full); 403 404 if (run_verification && VerifyAfterGC) { 405 HandleMark hm; // Discard invalid handles created during verification 406 Universe::verify(" VerifyAfterGC:"); 407 } 408 409 if (PrintGCDetails) { 410 gclog_or_tty->print(":"); 411 gen->print_heap_change(prev_used); 412 } 413 } 414 415 void GenCollectedHeap::do_collection(bool full, 416 bool clear_all_soft_refs, 417 size_t size, 418 bool is_tlab, 419 int max_level) { 420 ResourceMark rm; 421 DEBUG_ONLY(Thread* my_thread = Thread::current();) 422 423 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 424 assert(my_thread->is_VM_thread() || 425 my_thread->is_ConcurrentGC_thread(), 426 "incorrect thread type capability"); 427 assert(Heap_lock->is_locked(), 428 "the requesting thread should have the Heap_lock"); 429 guarantee(!is_gc_active(), "collection is not reentrant"); 430 431 if (GC_locker::check_active_before_gc()) { 432 return; // GC is disabled (e.g. JNI GetXXXCritical operation) 433 } 434 435 const bool do_clear_all_soft_refs = clear_all_soft_refs || 436 collector_policy()->should_clear_all_soft_refs(); 437 438 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 439 440 const size_t metadata_prev_used = MetaspaceAux::used_bytes(); 441 442 print_heap_before_gc(); 443 444 { 445 FlagSetting fl(_is_gc_active, true); 446 447 bool complete = full && (max_level == 1 /* old */); 448 const char* gc_cause_prefix = complete ? "Full GC" : "GC"; 449 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); 450 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later 451 // so we can assume here that the next GC id is what we want. 452 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek()); 453 454 gc_prologue(complete); 455 increment_total_collections(complete); 456 457 size_t gch_prev_used = used(); 458 bool run_verification = total_collections() >= VerifyGCStartAt; 459 460 bool prepared_for_verification = false; 461 int max_level_collected = 0; 462 bool old_collects_young = (max_level == 1) && 463 full && 464 _old_gen->full_collects_younger_generations(); 465 if (!old_collects_young && 466 _young_gen->should_collect(full, size, is_tlab)) { 467 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) { 468 prepare_for_verify(); 469 prepared_for_verification = true; 470 } 471 472 assert(!_young_gen->performs_in_place_marking(), "No young generation do in place marking"); 473 collect_generation(_young_gen, 474 full, 475 size, 476 is_tlab, 477 run_verification && VerifyGCLevel <= 0, 478 do_clear_all_soft_refs, 479 false); 480 481 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) && 482 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) { 483 // Allocation request was met by young GC. 484 size = 0; 485 } 486 } 487 488 bool must_restore_marks_for_biased_locking = false; 489 490 if (max_level == 1 && _old_gen->should_collect(full, size, is_tlab)) { 491 if (!complete) { 492 // The full_collections increment was missed above. 493 increment_total_full_collections(); 494 } 495 496 pre_full_gc_dump(NULL); // do any pre full gc dumps 497 498 if (!prepared_for_verification && run_verification && 499 VerifyGCLevel <= 1 && VerifyBeforeGC) { 500 prepare_for_verify(); 501 } 502 503 assert(_old_gen->performs_in_place_marking(), "All old generations do in place marking"); 504 collect_generation(_old_gen, 505 full, 506 size, 507 is_tlab, 508 run_verification && VerifyGCLevel <= 1, 509 do_clear_all_soft_refs, 510 true); 511 512 must_restore_marks_for_biased_locking = true; 513 max_level_collected = 1; 514 } 515 516 // Update "complete" boolean wrt what actually transpired -- 517 // for instance, a promotion failure could have led to 518 // a whole heap collection. 519 complete = complete || (max_level_collected == 1 /* old */); 520 521 if (complete) { // We did a "major" collection 522 // FIXME: See comment at pre_full_gc_dump call 523 post_full_gc_dump(NULL); // do any post full gc dumps 524 } 525 526 if (PrintGCDetails) { 527 print_heap_change(gch_prev_used); 528 529 // Print metaspace info for full GC with PrintGCDetails flag. 530 if (complete) { 531 MetaspaceAux::print_metaspace_change(metadata_prev_used); 532 } 533 } 534 535 // Adjust generation sizes. 536 if (max_level_collected == 1 /* old */) { 537 _old_gen->compute_new_size(); 538 } 539 _young_gen->compute_new_size(); 540 541 if (complete) { 542 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 543 ClassLoaderDataGraph::purge(); 544 MetaspaceAux::verify_metrics(); 545 // Resize the metaspace capacity after full collections 546 MetaspaceGC::compute_new_size(); 547 update_full_collections_completed(); 548 } 549 550 // Track memory usage and detect low memory after GC finishes 551 MemoryService::track_memory_usage(); 552 553 gc_epilogue(complete); 554 555 if (must_restore_marks_for_biased_locking) { 556 BiasedLocking::restore_marks(); 557 } 558 } 559 560 print_heap_after_gc(); 561 562 #ifdef TRACESPINNING 563 ParallelTaskTerminator::print_termination_counts(); 564 #endif 565 } 566 567 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) { 568 return collector_policy()->satisfy_failed_allocation(size, is_tlab); 569 } 570 571 #ifdef ASSERT 572 class AssertNonScavengableClosure: public OopClosure { 573 public: 574 virtual void do_oop(oop* p) { 575 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p), 576 "Referent should not be scavengable."); } 577 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); } 578 }; 579 static AssertNonScavengableClosure assert_is_non_scavengable_closure; 580 #endif 581 582 void GenCollectedHeap::process_roots(StrongRootsScope* scope, 583 ScanningOption so, 584 OopClosure* strong_roots, 585 OopClosure* weak_roots, 586 CLDClosure* strong_cld_closure, 587 CLDClosure* weak_cld_closure, 588 CodeBlobClosure* code_roots) { 589 // General roots. 590 assert(Threads::thread_claim_parity() != 0, "must have called prologue code"); 591 assert(code_roots != NULL, "code root closure should always be set"); 592 // _n_termination for _process_strong_tasks should be set up stream 593 // in a method not running in a GC worker. Otherwise the GC worker 594 // could be trying to change the termination condition while the task 595 // is executing in another GC worker. 596 597 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) { 598 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure); 599 } 600 601 // Some CLDs contained in the thread frames should be considered strong. 602 // Don't process them if they will be processed during the ClassLoaderDataGraph phase. 603 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL; 604 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway 605 CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots; 606 607 bool is_par = scope->n_threads() > 1; 608 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_clds_p, roots_from_code_p); 609 610 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) { 611 Universe::oops_do(strong_roots); 612 } 613 // Global (strong) JNI handles 614 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) { 615 JNIHandles::oops_do(strong_roots); 616 } 617 618 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) { 619 ObjectSynchronizer::oops_do(strong_roots); 620 } 621 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) { 622 FlatProfiler::oops_do(strong_roots); 623 } 624 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) { 625 Management::oops_do(strong_roots); 626 } 627 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) { 628 JvmtiExport::oops_do(strong_roots); 629 } 630 631 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) { 632 SystemDictionary::roots_oops_do(strong_roots, weak_roots); 633 } 634 635 // All threads execute the following. A specific chunk of buckets 636 // from the StringTable are the individual tasks. 637 if (weak_roots != NULL) { 638 if (is_par) { 639 StringTable::possibly_parallel_oops_do(weak_roots); 640 } else { 641 StringTable::oops_do(weak_roots); 642 } 643 } 644 645 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) { 646 if (so & SO_ScavengeCodeCache) { 647 assert(code_roots != NULL, "must supply closure for code cache"); 648 649 // We only visit parts of the CodeCache when scavenging. 650 CodeCache::scavenge_root_nmethods_do(code_roots); 651 } 652 if (so & SO_AllCodeCache) { 653 assert(code_roots != NULL, "must supply closure for code cache"); 654 655 // CMSCollector uses this to do intermediate-strength collections. 656 // We scan the entire code cache, since CodeCache::do_unloading is not called. 657 CodeCache::blobs_do(code_roots); 658 } 659 // Verify that the code cache contents are not subject to 660 // movement by a scavenging collection. 661 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations)); 662 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable)); 663 } 664 665 } 666 667 void GenCollectedHeap::gen_process_roots(StrongRootsScope* scope, 668 int level, 669 bool younger_gens_as_roots, 670 ScanningOption so, 671 bool only_strong_roots, 672 OopsInGenClosure* not_older_gens, 673 OopsInGenClosure* older_gens, 674 CLDClosure* cld_closure) { 675 const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots; 676 677 bool is_moving_collection = false; 678 if (level == 0 || is_adjust_phase) { 679 // young collections are always moving 680 is_moving_collection = true; 681 } 682 683 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection); 684 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens; 685 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure; 686 687 process_roots(scope, so, 688 not_older_gens, weak_roots, 689 cld_closure, weak_cld_closure, 690 &mark_code_closure); 691 692 if (younger_gens_as_roots) { 693 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) { 694 if (level == 1) { 695 not_older_gens->set_generation(_young_gen); 696 _young_gen->oop_iterate(not_older_gens); 697 } 698 not_older_gens->reset_generation(); 699 } 700 } 701 // When collection is parallel, all threads get to cooperate to do 702 // older-gen scanning. 703 if (level == 0) { 704 older_gens->set_generation(_old_gen); 705 rem_set()->younger_refs_iterate(_old_gen, older_gens, scope->n_threads()); 706 older_gens->reset_generation(); 707 } 708 709 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 710 } 711 712 713 class AlwaysTrueClosure: public BoolObjectClosure { 714 public: 715 bool do_object_b(oop p) { return true; } 716 }; 717 static AlwaysTrueClosure always_true; 718 719 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) { 720 JNIHandles::weak_oops_do(&always_true, root_closure); 721 _young_gen->ref_processor()->weak_oops_do(root_closure); 722 _old_gen->ref_processor()->weak_oops_do(root_closure); 723 } 724 725 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \ 726 void GenCollectedHeap:: \ 727 oop_since_save_marks_iterate(int level, \ 728 OopClosureType* cur, \ 729 OopClosureType* older) { \ 730 if (level == 0) { \ 731 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 732 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \ 733 } else { \ 734 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 735 } \ 736 } 737 738 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN) 739 740 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN 741 742 bool GenCollectedHeap::no_allocs_since_save_marks(int level) { 743 if (level == 0 && !_young_gen->no_allocs_since_save_marks()) { 744 return false; 745 } 746 return _old_gen->no_allocs_since_save_marks(); 747 } 748 749 bool GenCollectedHeap::supports_inline_contig_alloc() const { 750 return _young_gen->supports_inline_contig_alloc(); 751 } 752 753 HeapWord** GenCollectedHeap::top_addr() const { 754 return _young_gen->top_addr(); 755 } 756 757 HeapWord** GenCollectedHeap::end_addr() const { 758 return _young_gen->end_addr(); 759 } 760 761 // public collection interfaces 762 763 void GenCollectedHeap::collect(GCCause::Cause cause) { 764 if (should_do_concurrent_full_gc(cause)) { 765 #if INCLUDE_ALL_GCS 766 // mostly concurrent full collection 767 collect_mostly_concurrent(cause); 768 #else // INCLUDE_ALL_GCS 769 ShouldNotReachHere(); 770 #endif // INCLUDE_ALL_GCS 771 } else if (cause == GCCause::_wb_young_gc) { 772 // minor collection for WhiteBox API 773 collect(cause, 0 /* young */); 774 } else { 775 #ifdef ASSERT 776 if (cause == GCCause::_scavenge_alot) { 777 // minor collection only 778 collect(cause, 0 /* young */); 779 } else { 780 // Stop-the-world full collection 781 collect(cause, 1 /* old */); 782 } 783 #else 784 // Stop-the-world full collection 785 collect(cause, 1 /* old */); 786 #endif 787 } 788 } 789 790 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) { 791 // The caller doesn't have the Heap_lock 792 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); 793 MutexLocker ml(Heap_lock); 794 collect_locked(cause, max_level); 795 } 796 797 void GenCollectedHeap::collect_locked(GCCause::Cause cause) { 798 // The caller has the Heap_lock 799 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock"); 800 collect_locked(cause, 1 /* old */); 801 } 802 803 // this is the private collection interface 804 // The Heap_lock is expected to be held on entry. 805 806 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) { 807 // Read the GC count while holding the Heap_lock 808 unsigned int gc_count_before = total_collections(); 809 unsigned int full_gc_count_before = total_full_collections(); 810 { 811 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back 812 VM_GenCollectFull op(gc_count_before, full_gc_count_before, 813 cause, max_level); 814 VMThread::execute(&op); 815 } 816 } 817 818 #if INCLUDE_ALL_GCS 819 bool GenCollectedHeap::create_cms_collector() { 820 821 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep, 822 "Unexpected generation kinds"); 823 // Skip two header words in the block content verification 824 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();) 825 CMSCollector* collector = new CMSCollector( 826 (ConcurrentMarkSweepGeneration*)_old_gen, 827 _rem_set->as_CardTableRS(), 828 (ConcurrentMarkSweepPolicy*) collector_policy()); 829 830 if (collector == NULL || !collector->completed_initialization()) { 831 if (collector) { 832 delete collector; // Be nice in embedded situation 833 } 834 vm_shutdown_during_initialization("Could not create CMS collector"); 835 return false; 836 } 837 return true; // success 838 } 839 840 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) { 841 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock"); 842 843 MutexLocker ml(Heap_lock); 844 // Read the GC counts while holding the Heap_lock 845 unsigned int full_gc_count_before = total_full_collections(); 846 unsigned int gc_count_before = total_collections(); 847 { 848 MutexUnlocker mu(Heap_lock); 849 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause); 850 VMThread::execute(&op); 851 } 852 } 853 #endif // INCLUDE_ALL_GCS 854 855 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) { 856 do_full_collection(clear_all_soft_refs, 1 /* old */); 857 } 858 859 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs, 860 int max_level) { 861 int local_max_level; 862 if (!incremental_collection_will_fail(false /* don't consult_young */) && 863 gc_cause() == GCCause::_gc_locker) { 864 local_max_level = 0; 865 } else { 866 local_max_level = max_level; 867 } 868 869 do_collection(true /* full */, 870 clear_all_soft_refs /* clear_all_soft_refs */, 871 0 /* size */, 872 false /* is_tlab */, 873 local_max_level /* max_level */); 874 // Hack XXX FIX ME !!! 875 // A scavenge may not have been attempted, or may have 876 // been attempted and failed, because the old gen was too full 877 if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker && 878 incremental_collection_will_fail(false /* don't consult_young */)) { 879 if (PrintGCDetails) { 880 gclog_or_tty->print_cr("GC locker: Trying a full collection " 881 "because scavenge failed"); 882 } 883 // This time allow the old gen to be collected as well 884 do_collection(true /* full */, 885 clear_all_soft_refs /* clear_all_soft_refs */, 886 0 /* size */, 887 false /* is_tlab */, 888 1 /* old */ /* max_level */); 889 } 890 } 891 892 bool GenCollectedHeap::is_in_young(oop p) { 893 bool result = ((HeapWord*)p) < _old_gen->reserved().start(); 894 assert(result == _young_gen->is_in_reserved(p), 895 err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p))); 896 return result; 897 } 898 899 // Returns "TRUE" iff "p" points into the committed areas of the heap. 900 bool GenCollectedHeap::is_in(const void* p) const { 901 return _young_gen->is_in(p) || _old_gen->is_in(p); 902 } 903 904 #ifdef ASSERT 905 // Don't implement this by using is_in_young(). This method is used 906 // in some cases to check that is_in_young() is correct. 907 bool GenCollectedHeap::is_in_partial_collection(const void* p) { 908 assert(is_in_reserved(p) || p == NULL, 909 "Does not work if address is non-null and outside of the heap"); 910 return p < _young_gen->reserved().end() && p != NULL; 911 } 912 #endif 913 914 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) { 915 NoHeaderExtendedOopClosure no_header_cl(cl); 916 oop_iterate(&no_header_cl); 917 } 918 919 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 920 _young_gen->oop_iterate(cl); 921 _old_gen->oop_iterate(cl); 922 } 923 924 void GenCollectedHeap::object_iterate(ObjectClosure* cl) { 925 _young_gen->object_iterate(cl); 926 _old_gen->object_iterate(cl); 927 } 928 929 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) { 930 _young_gen->safe_object_iterate(cl); 931 _old_gen->safe_object_iterate(cl); 932 } 933 934 Space* GenCollectedHeap::space_containing(const void* addr) const { 935 Space* res = _young_gen->space_containing(addr); 936 if (res != NULL) { 937 return res; 938 } 939 res = _old_gen->space_containing(addr); 940 assert(res != NULL, "Could not find containing space"); 941 return res; 942 } 943 944 HeapWord* GenCollectedHeap::block_start(const void* addr) const { 945 assert(is_in_reserved(addr), "block_start of address outside of heap"); 946 if (_young_gen->is_in_reserved(addr)) { 947 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 948 return _young_gen->block_start(addr); 949 } 950 951 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 952 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 953 return _old_gen->block_start(addr); 954 } 955 956 size_t GenCollectedHeap::block_size(const HeapWord* addr) const { 957 assert(is_in_reserved(addr), "block_size of address outside of heap"); 958 if (_young_gen->is_in_reserved(addr)) { 959 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 960 return _young_gen->block_size(addr); 961 } 962 963 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 964 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 965 return _old_gen->block_size(addr); 966 } 967 968 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const { 969 assert(is_in_reserved(addr), "block_is_obj of address outside of heap"); 970 assert(block_start(addr) == addr, "addr must be a block start"); 971 if (_young_gen->is_in_reserved(addr)) { 972 return _young_gen->block_is_obj(addr); 973 } 974 975 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 976 return _old_gen->block_is_obj(addr); 977 } 978 979 bool GenCollectedHeap::supports_tlab_allocation() const { 980 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 981 return _young_gen->supports_tlab_allocation(); 982 } 983 984 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const { 985 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 986 if (_young_gen->supports_tlab_allocation()) { 987 return _young_gen->tlab_capacity(); 988 } 989 return 0; 990 } 991 992 size_t GenCollectedHeap::tlab_used(Thread* thr) const { 993 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 994 if (_young_gen->supports_tlab_allocation()) { 995 return _young_gen->tlab_used(); 996 } 997 return 0; 998 } 999 1000 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const { 1001 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1002 if (_young_gen->supports_tlab_allocation()) { 1003 return _young_gen->unsafe_max_tlab_alloc(); 1004 } 1005 return 0; 1006 } 1007 1008 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) { 1009 bool gc_overhead_limit_was_exceeded; 1010 return collector_policy()->mem_allocate_work(size /* size */, 1011 true /* is_tlab */, 1012 &gc_overhead_limit_was_exceeded); 1013 } 1014 1015 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size 1016 // from the list headed by "*prev_ptr". 1017 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) { 1018 bool first = true; 1019 size_t min_size = 0; // "first" makes this conceptually infinite. 1020 ScratchBlock **smallest_ptr, *smallest; 1021 ScratchBlock *cur = *prev_ptr; 1022 while (cur) { 1023 assert(*prev_ptr == cur, "just checking"); 1024 if (first || cur->num_words < min_size) { 1025 smallest_ptr = prev_ptr; 1026 smallest = cur; 1027 min_size = smallest->num_words; 1028 first = false; 1029 } 1030 prev_ptr = &cur->next; 1031 cur = cur->next; 1032 } 1033 smallest = *smallest_ptr; 1034 *smallest_ptr = smallest->next; 1035 return smallest; 1036 } 1037 1038 // Sort the scratch block list headed by res into decreasing size order, 1039 // and set "res" to the result. 1040 static void sort_scratch_list(ScratchBlock*& list) { 1041 ScratchBlock* sorted = NULL; 1042 ScratchBlock* unsorted = list; 1043 while (unsorted) { 1044 ScratchBlock *smallest = removeSmallestScratch(&unsorted); 1045 smallest->next = sorted; 1046 sorted = smallest; 1047 } 1048 list = sorted; 1049 } 1050 1051 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor, 1052 size_t max_alloc_words) { 1053 ScratchBlock* res = NULL; 1054 _young_gen->contribute_scratch(res, requestor, max_alloc_words); 1055 _old_gen->contribute_scratch(res, requestor, max_alloc_words); 1056 sort_scratch_list(res); 1057 return res; 1058 } 1059 1060 void GenCollectedHeap::release_scratch() { 1061 _young_gen->reset_scratch(); 1062 _old_gen->reset_scratch(); 1063 } 1064 1065 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure { 1066 void do_generation(Generation* gen) { 1067 gen->prepare_for_verify(); 1068 } 1069 }; 1070 1071 void GenCollectedHeap::prepare_for_verify() { 1072 ensure_parsability(false); // no need to retire TLABs 1073 GenPrepareForVerifyClosure blk; 1074 generation_iterate(&blk, false); 1075 } 1076 1077 void GenCollectedHeap::generation_iterate(GenClosure* cl, 1078 bool old_to_young) { 1079 if (old_to_young) { 1080 cl->do_generation(_old_gen); 1081 cl->do_generation(_young_gen); 1082 } else { 1083 cl->do_generation(_young_gen); 1084 cl->do_generation(_old_gen); 1085 } 1086 } 1087 1088 bool GenCollectedHeap::is_maximal_no_gc() const { 1089 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc(); 1090 } 1091 1092 void GenCollectedHeap::save_marks() { 1093 _young_gen->save_marks(); 1094 _old_gen->save_marks(); 1095 } 1096 1097 GenCollectedHeap* GenCollectedHeap::heap() { 1098 CollectedHeap* heap = Universe::heap(); 1099 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()"); 1100 assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Not a GenCollectedHeap"); 1101 return (GenCollectedHeap*)heap; 1102 } 1103 1104 void GenCollectedHeap::prepare_for_compaction() { 1105 // Start by compacting into same gen. 1106 CompactPoint cp(_old_gen); 1107 _old_gen->prepare_for_compaction(&cp); 1108 _young_gen->prepare_for_compaction(&cp); 1109 } 1110 1111 GCStats* GenCollectedHeap::gc_stats(int level) const { 1112 if (level == 0) { 1113 return _young_gen->gc_stats(); 1114 } else { 1115 return _old_gen->gc_stats(); 1116 } 1117 } 1118 1119 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) { 1120 if (!silent) { 1121 gclog_or_tty->print("%s", _old_gen->name()); 1122 gclog_or_tty->print(" "); 1123 } 1124 _old_gen->verify(); 1125 1126 if (!silent) { 1127 gclog_or_tty->print("%s", _young_gen->name()); 1128 gclog_or_tty->print(" "); 1129 } 1130 _young_gen->verify(); 1131 1132 if (!silent) { 1133 gclog_or_tty->print("remset "); 1134 } 1135 rem_set()->verify(); 1136 } 1137 1138 void GenCollectedHeap::print_on(outputStream* st) const { 1139 _young_gen->print_on(st); 1140 _old_gen->print_on(st); 1141 MetaspaceAux::print_on(st); 1142 } 1143 1144 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const { 1145 if (workers() != NULL) { 1146 workers()->threads_do(tc); 1147 } 1148 #if INCLUDE_ALL_GCS 1149 if (UseConcMarkSweepGC) { 1150 ConcurrentMarkSweepThread::threads_do(tc); 1151 } 1152 #endif // INCLUDE_ALL_GCS 1153 } 1154 1155 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const { 1156 #if INCLUDE_ALL_GCS 1157 if (UseConcMarkSweepGC) { 1158 workers()->print_worker_threads_on(st); 1159 ConcurrentMarkSweepThread::print_all_on(st); 1160 } 1161 #endif // INCLUDE_ALL_GCS 1162 } 1163 1164 void GenCollectedHeap::print_on_error(outputStream* st) const { 1165 this->CollectedHeap::print_on_error(st); 1166 1167 #if INCLUDE_ALL_GCS 1168 if (UseConcMarkSweepGC) { 1169 st->cr(); 1170 CMSCollector::print_on_error(st); 1171 } 1172 #endif // INCLUDE_ALL_GCS 1173 } 1174 1175 void GenCollectedHeap::print_tracing_info() const { 1176 if (TraceYoungGenTime) { 1177 _young_gen->print_summary_info(); 1178 } 1179 if (TraceOldGenTime) { 1180 _old_gen->print_summary_info(); 1181 } 1182 } 1183 1184 void GenCollectedHeap::print_heap_change(size_t prev_used) const { 1185 if (PrintGCDetails && Verbose) { 1186 gclog_or_tty->print(" " SIZE_FORMAT 1187 "->" SIZE_FORMAT 1188 "(" SIZE_FORMAT ")", 1189 prev_used, used(), capacity()); 1190 } else { 1191 gclog_or_tty->print(" " SIZE_FORMAT "K" 1192 "->" SIZE_FORMAT "K" 1193 "(" SIZE_FORMAT "K)", 1194 prev_used / K, used() / K, capacity() / K); 1195 } 1196 } 1197 1198 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure { 1199 private: 1200 bool _full; 1201 public: 1202 void do_generation(Generation* gen) { 1203 gen->gc_prologue(_full); 1204 } 1205 GenGCPrologueClosure(bool full) : _full(full) {}; 1206 }; 1207 1208 void GenCollectedHeap::gc_prologue(bool full) { 1209 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 1210 1211 always_do_update_barrier = false; 1212 // Fill TLAB's and such 1213 CollectedHeap::accumulate_statistics_all_tlabs(); 1214 ensure_parsability(true); // retire TLABs 1215 1216 // Walk generations 1217 GenGCPrologueClosure blk(full); 1218 generation_iterate(&blk, false); // not old-to-young. 1219 }; 1220 1221 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure { 1222 private: 1223 bool _full; 1224 public: 1225 void do_generation(Generation* gen) { 1226 gen->gc_epilogue(_full); 1227 } 1228 GenGCEpilogueClosure(bool full) : _full(full) {}; 1229 }; 1230 1231 void GenCollectedHeap::gc_epilogue(bool full) { 1232 #ifdef COMPILER2 1233 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 1234 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr())); 1235 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps"); 1236 #endif /* COMPILER2 */ 1237 1238 resize_all_tlabs(); 1239 1240 GenGCEpilogueClosure blk(full); 1241 generation_iterate(&blk, false); // not old-to-young. 1242 1243 if (!CleanChunkPoolAsync) { 1244 Chunk::clean_chunk_pool(); 1245 } 1246 1247 MetaspaceCounters::update_performance_counters(); 1248 CompressedClassSpaceCounters::update_performance_counters(); 1249 1250 always_do_update_barrier = UseConcMarkSweepGC; 1251 }; 1252 1253 #ifndef PRODUCT 1254 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure { 1255 private: 1256 public: 1257 void do_generation(Generation* gen) { 1258 gen->record_spaces_top(); 1259 } 1260 }; 1261 1262 void GenCollectedHeap::record_gen_tops_before_GC() { 1263 if (ZapUnusedHeapArea) { 1264 GenGCSaveTopsBeforeGCClosure blk; 1265 generation_iterate(&blk, false); // not old-to-young. 1266 } 1267 } 1268 #endif // not PRODUCT 1269 1270 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure { 1271 public: 1272 void do_generation(Generation* gen) { 1273 gen->ensure_parsability(); 1274 } 1275 }; 1276 1277 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) { 1278 CollectedHeap::ensure_parsability(retire_tlabs); 1279 GenEnsureParsabilityClosure ep_cl; 1280 generation_iterate(&ep_cl, false); 1281 } 1282 1283 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen, 1284 oop obj, 1285 size_t obj_size) { 1286 guarantee(old_gen->level() == 1, "We only get here with an old generation"); 1287 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); 1288 HeapWord* result = NULL; 1289 1290 result = old_gen->expand_and_allocate(obj_size, false); 1291 1292 if (result != NULL) { 1293 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size); 1294 } 1295 return oop(result); 1296 } 1297 1298 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure { 1299 jlong _time; // in ms 1300 jlong _now; // in ms 1301 1302 public: 1303 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { } 1304 1305 jlong time() { return _time; } 1306 1307 void do_generation(Generation* gen) { 1308 _time = MIN2(_time, gen->time_of_last_gc(_now)); 1309 } 1310 }; 1311 1312 jlong GenCollectedHeap::millis_since_last_gc() { 1313 // We need a monotonically non-decreasing time in ms but 1314 // os::javaTimeMillis() does not guarantee monotonicity. 1315 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 1316 GenTimeOfLastGCClosure tolgc_cl(now); 1317 // iterate over generations getting the oldest 1318 // time that a generation was collected 1319 generation_iterate(&tolgc_cl, false); 1320 1321 // javaTimeNanos() is guaranteed to be monotonically non-decreasing 1322 // provided the underlying platform provides such a time source 1323 // (and it is bug free). So we still have to guard against getting 1324 // back a time later than 'now'. 1325 jlong retVal = now - tolgc_cl.time(); 1326 if (retVal < 0) { 1327 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);) 1328 return 0; 1329 } 1330 return retVal; 1331 }