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 return UseConcMarkSweepGC && 308 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) || 309 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent)); 310 } 311 312 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size, 313 bool is_tlab, bool run_verification, bool clear_soft_refs, 314 bool restore_marks_for_biased_locking) { 315 // Timer for individual generations. Last argument is false: no CR 316 // FIXME: We should try to start the timing earlier to cover more of the GC pause 317 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later 318 // so we can assume here that the next GC id is what we want. 319 GCTraceTime t1(gen->short_name(), PrintGCDetails, false, NULL, GCId::peek()); 320 TraceCollectorStats tcs(gen->counters()); 321 TraceMemoryManagerStats tmms(gen->kind(),gc_cause()); 322 323 size_t prev_used = gen->used(); 324 gen->stat_record()->invocations++; 325 gen->stat_record()->accumulated_time.start(); 326 327 // Must be done anew before each collection because 328 // a previous collection will do mangling and will 329 // change top of some spaces. 330 record_gen_tops_before_GC(); 331 332 if (PrintGC && Verbose) { 333 gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT, 334 gen->level(), 335 gen->stat_record()->invocations, 336 size * HeapWordSize); 337 } 338 339 if (run_verification && VerifyBeforeGC) { 340 HandleMark hm; // Discard invalid handles created during verification 341 Universe::verify(" VerifyBeforeGC:"); 342 } 343 COMPILER2_PRESENT(DerivedPointerTable::clear()); 344 345 if (restore_marks_for_biased_locking) { 346 // We perform this mark word preservation work lazily 347 // because it's only at this point that we know whether we 348 // absolutely have to do it; we want to avoid doing it for 349 // scavenge-only collections where it's unnecessary 350 BiasedLocking::preserve_marks(); 351 } 352 353 // Do collection work 354 { 355 // Note on ref discovery: For what appear to be historical reasons, 356 // GCH enables and disabled (by enqueing) refs discovery. 357 // In the future this should be moved into the generation's 358 // collect method so that ref discovery and enqueueing concerns 359 // are local to a generation. The collect method could return 360 // an appropriate indication in the case that notification on 361 // the ref lock was needed. This will make the treatment of 362 // weak refs more uniform (and indeed remove such concerns 363 // from GCH). XXX 364 365 HandleMark hm; // Discard invalid handles created during gc 366 save_marks(); // save marks for all gens 367 // We want to discover references, but not process them yet. 368 // This mode is disabled in process_discovered_references if the 369 // generation does some collection work, or in 370 // enqueue_discovered_references if the generation returns 371 // without doing any work. 372 ReferenceProcessor* rp = gen->ref_processor(); 373 // If the discovery of ("weak") refs in this generation is 374 // atomic wrt other collectors in this configuration, we 375 // are guaranteed to have empty discovered ref lists. 376 if (rp->discovery_is_atomic()) { 377 rp->enable_discovery(); 378 rp->setup_policy(clear_soft_refs); 379 } else { 380 // collect() below will enable discovery as appropriate 381 } 382 gen->collect(full, clear_soft_refs, size, is_tlab); 383 if (!rp->enqueuing_is_done()) { 384 rp->enqueue_discovered_references(); 385 } else { 386 rp->set_enqueuing_is_done(false); 387 } 388 rp->verify_no_references_recorded(); 389 } 390 391 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 392 393 gen->stat_record()->accumulated_time.stop(); 394 395 update_gc_stats(gen->level(), full); 396 397 if (run_verification && VerifyAfterGC) { 398 HandleMark hm; // Discard invalid handles created during verification 399 Universe::verify(" VerifyAfterGC:"); 400 } 401 402 if (PrintGCDetails) { 403 gclog_or_tty->print(":"); 404 gen->print_heap_change(prev_used); 405 } 406 } 407 408 void GenCollectedHeap::do_collection(bool full, 409 bool clear_all_soft_refs, 410 size_t size, 411 bool is_tlab, 412 int max_level) { 413 ResourceMark rm; 414 DEBUG_ONLY(Thread* my_thread = Thread::current();) 415 416 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 417 assert(my_thread->is_VM_thread() || 418 my_thread->is_ConcurrentGC_thread(), 419 "incorrect thread type capability"); 420 assert(Heap_lock->is_locked(), 421 "the requesting thread should have the Heap_lock"); 422 guarantee(!is_gc_active(), "collection is not reentrant"); 423 424 if (GC_locker::check_active_before_gc()) { 425 return; // GC is disabled (e.g. JNI GetXXXCritical operation) 426 } 427 428 const bool do_clear_all_soft_refs = clear_all_soft_refs || 429 collector_policy()->should_clear_all_soft_refs(); 430 431 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 432 433 const size_t metadata_prev_used = MetaspaceAux::used_bytes(); 434 435 print_heap_before_gc(); 436 437 { 438 FlagSetting fl(_is_gc_active, true); 439 440 bool complete = full && (max_level == 1 /* old */); 441 const char* gc_cause_prefix = complete ? "Full GC" : "GC"; 442 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); 443 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later 444 // so we can assume here that the next GC id is what we want. 445 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek()); 446 447 gc_prologue(complete); 448 increment_total_collections(complete); 449 450 size_t gch_prev_used = used(); 451 bool run_verification = total_collections() >= VerifyGCStartAt; 452 453 bool prepared_for_verification = false; 454 int max_level_collected = 0; 455 bool old_collects_young = (max_level == 1) && 456 full && 457 _old_gen->full_collects_younger_generations(); 458 if (!old_collects_young && 459 _young_gen->should_collect(full, size, is_tlab)) { 460 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) { 461 prepare_for_verify(); 462 prepared_for_verification = true; 463 } 464 465 assert(!_young_gen->performs_in_place_marking(), "No young generation do in place marking"); 466 collect_generation(_young_gen, 467 full, 468 size, 469 is_tlab, 470 run_verification && VerifyGCLevel <= 0, 471 do_clear_all_soft_refs, 472 false); 473 474 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) && 475 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) { 476 // Allocation request was met by young GC. 477 size = 0; 478 } 479 } 480 481 bool must_restore_marks_for_biased_locking = false; 482 483 if (max_level == 1 && _old_gen->should_collect(full, size, is_tlab)) { 484 if (!complete) { 485 // The full_collections increment was missed above. 486 increment_total_full_collections(); 487 } 488 489 pre_full_gc_dump(NULL); // do any pre full gc dumps 490 491 if (!prepared_for_verification && run_verification && 492 VerifyGCLevel <= 1 && VerifyBeforeGC) { 493 prepare_for_verify(); 494 } 495 496 assert(_old_gen->performs_in_place_marking(), "All old generations do in place marking"); 497 collect_generation(_old_gen, 498 full, 499 size, 500 is_tlab, 501 run_verification && VerifyGCLevel <= 1, 502 do_clear_all_soft_refs, 503 true); 504 505 must_restore_marks_for_biased_locking = true; 506 max_level_collected = 1; 507 } 508 509 // Update "complete" boolean wrt what actually transpired -- 510 // for instance, a promotion failure could have led to 511 // a whole heap collection. 512 complete = complete || (max_level_collected == 1 /* old */); 513 514 if (complete) { // We did a "major" collection 515 // FIXME: See comment at pre_full_gc_dump call 516 post_full_gc_dump(NULL); // do any post full gc dumps 517 } 518 519 if (PrintGCDetails) { 520 print_heap_change(gch_prev_used); 521 522 // Print metaspace info for full GC with PrintGCDetails flag. 523 if (complete) { 524 MetaspaceAux::print_metaspace_change(metadata_prev_used); 525 } 526 } 527 528 // Adjust generation sizes. 529 if (max_level_collected == 1 /* old */) { 530 _old_gen->compute_new_size(); 531 } 532 _young_gen->compute_new_size(); 533 534 if (complete) { 535 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 536 ClassLoaderDataGraph::purge(); 537 MetaspaceAux::verify_metrics(); 538 // Resize the metaspace capacity after full collections 539 MetaspaceGC::compute_new_size(); 540 update_full_collections_completed(); 541 } 542 543 // Track memory usage and detect low memory after GC finishes 544 MemoryService::track_memory_usage(); 545 546 gc_epilogue(complete); 547 548 if (must_restore_marks_for_biased_locking) { 549 BiasedLocking::restore_marks(); 550 } 551 } 552 553 print_heap_after_gc(); 554 555 #ifdef TRACESPINNING 556 ParallelTaskTerminator::print_termination_counts(); 557 #endif 558 } 559 560 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) { 561 return collector_policy()->satisfy_failed_allocation(size, is_tlab); 562 } 563 564 void GenCollectedHeap::set_par_threads(uint t) { 565 assert(t == 0 || !UseSerialGC, "Cannot have parallel threads"); 566 CollectedHeap::set_par_threads(t); 567 } 568 569 #ifdef ASSERT 570 class AssertNonScavengableClosure: public OopClosure { 571 public: 572 virtual void do_oop(oop* p) { 573 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p), 574 "Referent should not be scavengable."); } 575 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); } 576 }; 577 static AssertNonScavengableClosure assert_is_non_scavengable_closure; 578 #endif 579 580 void GenCollectedHeap::process_roots(StrongRootsScope* scope, 581 ScanningOption so, 582 OopClosure* strong_roots, 583 OopClosure* weak_roots, 584 CLDClosure* strong_cld_closure, 585 CLDClosure* weak_cld_closure, 586 CodeBlobClosure* code_roots) { 587 // General roots. 588 assert(Threads::thread_claim_parity() != 0, "must have called prologue code"); 589 assert(code_roots != NULL, "code root closure should always be set"); 590 // _n_termination for _process_strong_tasks should be set up stream 591 // in a method not running in a GC worker. Otherwise the GC worker 592 // could be trying to change the termination condition while the task 593 // is executing in another GC worker. 594 595 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) { 596 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure); 597 } 598 599 // Some CLDs contained in the thread frames should be considered strong. 600 // Don't process them if they will be processed during the ClassLoaderDataGraph phase. 601 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL; 602 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway 603 CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots; 604 605 bool is_par = scope->n_threads() > 1; 606 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_clds_p, roots_from_code_p); 607 608 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) { 609 Universe::oops_do(strong_roots); 610 } 611 // Global (strong) JNI handles 612 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) { 613 JNIHandles::oops_do(strong_roots); 614 } 615 616 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) { 617 ObjectSynchronizer::oops_do(strong_roots); 618 } 619 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) { 620 FlatProfiler::oops_do(strong_roots); 621 } 622 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) { 623 Management::oops_do(strong_roots); 624 } 625 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) { 626 JvmtiExport::oops_do(strong_roots); 627 } 628 629 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) { 630 SystemDictionary::roots_oops_do(strong_roots, weak_roots); 631 } 632 633 // All threads execute the following. A specific chunk of buckets 634 // from the StringTable are the individual tasks. 635 if (weak_roots != NULL) { 636 if (is_par) { 637 StringTable::possibly_parallel_oops_do(weak_roots); 638 } else { 639 StringTable::oops_do(weak_roots); 640 } 641 } 642 643 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) { 644 if (so & SO_ScavengeCodeCache) { 645 assert(code_roots != NULL, "must supply closure for code cache"); 646 647 // We only visit parts of the CodeCache when scavenging. 648 CodeCache::scavenge_root_nmethods_do(code_roots); 649 } 650 if (so & SO_AllCodeCache) { 651 assert(code_roots != NULL, "must supply closure for code cache"); 652 653 // CMSCollector uses this to do intermediate-strength collections. 654 // We scan the entire code cache, since CodeCache::do_unloading is not called. 655 CodeCache::blobs_do(code_roots); 656 } 657 // Verify that the code cache contents are not subject to 658 // movement by a scavenging collection. 659 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations)); 660 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable)); 661 } 662 663 } 664 665 void GenCollectedHeap::gen_process_roots(StrongRootsScope* scope, 666 int level, 667 bool younger_gens_as_roots, 668 ScanningOption so, 669 bool only_strong_roots, 670 OopsInGenClosure* not_older_gens, 671 OopsInGenClosure* older_gens, 672 CLDClosure* cld_closure) { 673 const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots; 674 675 bool is_moving_collection = false; 676 if (level == 0 || is_adjust_phase) { 677 // young collections are always moving 678 is_moving_collection = true; 679 } 680 681 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection); 682 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens; 683 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure; 684 685 process_roots(scope, so, 686 not_older_gens, weak_roots, 687 cld_closure, weak_cld_closure, 688 &mark_code_closure); 689 690 if (younger_gens_as_roots) { 691 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) { 692 if (level == 1) { 693 not_older_gens->set_generation(_young_gen); 694 _young_gen->oop_iterate(not_older_gens); 695 } 696 not_older_gens->reset_generation(); 697 } 698 } 699 // When collection is parallel, all threads get to cooperate to do 700 // older-gen scanning. 701 if (level == 0) { 702 older_gens->set_generation(_old_gen); 703 rem_set()->younger_refs_iterate(_old_gen, older_gens); 704 older_gens->reset_generation(); 705 } 706 707 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 708 } 709 710 711 class AlwaysTrueClosure: public BoolObjectClosure { 712 public: 713 bool do_object_b(oop p) { return true; } 714 }; 715 static AlwaysTrueClosure always_true; 716 717 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) { 718 JNIHandles::weak_oops_do(&always_true, root_closure); 719 _young_gen->ref_processor()->weak_oops_do(root_closure); 720 _old_gen->ref_processor()->weak_oops_do(root_closure); 721 } 722 723 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \ 724 void GenCollectedHeap:: \ 725 oop_since_save_marks_iterate(int level, \ 726 OopClosureType* cur, \ 727 OopClosureType* older) { \ 728 if (level == 0) { \ 729 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 730 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \ 731 } else { \ 732 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 733 } \ 734 } 735 736 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN) 737 738 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN 739 740 bool GenCollectedHeap::no_allocs_since_save_marks(int level) { 741 if (level == 0 && !_young_gen->no_allocs_since_save_marks()) { 742 return false; 743 } 744 return _old_gen->no_allocs_since_save_marks(); 745 } 746 747 bool GenCollectedHeap::supports_inline_contig_alloc() const { 748 return _young_gen->supports_inline_contig_alloc(); 749 } 750 751 HeapWord** GenCollectedHeap::top_addr() const { 752 return _young_gen->top_addr(); 753 } 754 755 HeapWord** GenCollectedHeap::end_addr() const { 756 return _young_gen->end_addr(); 757 } 758 759 // public collection interfaces 760 761 void GenCollectedHeap::collect(GCCause::Cause cause) { 762 if (should_do_concurrent_full_gc(cause)) { 763 #if INCLUDE_ALL_GCS 764 // mostly concurrent full collection 765 collect_mostly_concurrent(cause); 766 #else // INCLUDE_ALL_GCS 767 ShouldNotReachHere(); 768 #endif // INCLUDE_ALL_GCS 769 } else if (cause == GCCause::_wb_young_gc) { 770 // minor collection for WhiteBox API 771 collect(cause, 0 /* young */); 772 } else { 773 #ifdef ASSERT 774 if (cause == GCCause::_scavenge_alot) { 775 // minor collection only 776 collect(cause, 0 /* young */); 777 } else { 778 // Stop-the-world full collection 779 collect(cause, 1 /* old */); 780 } 781 #else 782 // Stop-the-world full collection 783 collect(cause, 1 /* old */); 784 #endif 785 } 786 } 787 788 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) { 789 // The caller doesn't have the Heap_lock 790 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); 791 MutexLocker ml(Heap_lock); 792 collect_locked(cause, max_level); 793 } 794 795 void GenCollectedHeap::collect_locked(GCCause::Cause cause) { 796 // The caller has the Heap_lock 797 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock"); 798 collect_locked(cause, 1 /* old */); 799 } 800 801 // this is the private collection interface 802 // The Heap_lock is expected to be held on entry. 803 804 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) { 805 // Read the GC count while holding the Heap_lock 806 unsigned int gc_count_before = total_collections(); 807 unsigned int full_gc_count_before = total_full_collections(); 808 { 809 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back 810 VM_GenCollectFull op(gc_count_before, full_gc_count_before, 811 cause, max_level); 812 VMThread::execute(&op); 813 } 814 } 815 816 #if INCLUDE_ALL_GCS 817 bool GenCollectedHeap::create_cms_collector() { 818 819 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep, 820 "Unexpected generation kinds"); 821 // Skip two header words in the block content verification 822 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();) 823 CMSCollector* collector = new CMSCollector( 824 (ConcurrentMarkSweepGeneration*)_old_gen, 825 _rem_set->as_CardTableRS(), 826 (ConcurrentMarkSweepPolicy*) collector_policy()); 827 828 if (collector == NULL || !collector->completed_initialization()) { 829 if (collector) { 830 delete collector; // Be nice in embedded situation 831 } 832 vm_shutdown_during_initialization("Could not create CMS collector"); 833 return false; 834 } 835 return true; // success 836 } 837 838 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) { 839 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock"); 840 841 MutexLocker ml(Heap_lock); 842 // Read the GC counts while holding the Heap_lock 843 unsigned int full_gc_count_before = total_full_collections(); 844 unsigned int gc_count_before = total_collections(); 845 { 846 MutexUnlocker mu(Heap_lock); 847 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause); 848 VMThread::execute(&op); 849 } 850 } 851 #endif // INCLUDE_ALL_GCS 852 853 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) { 854 do_full_collection(clear_all_soft_refs, 1 /* old */); 855 } 856 857 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs, 858 int max_level) { 859 int local_max_level; 860 if (!incremental_collection_will_fail(false /* don't consult_young */) && 861 gc_cause() == GCCause::_gc_locker) { 862 local_max_level = 0; 863 } else { 864 local_max_level = max_level; 865 } 866 867 do_collection(true /* full */, 868 clear_all_soft_refs /* clear_all_soft_refs */, 869 0 /* size */, 870 false /* is_tlab */, 871 local_max_level /* max_level */); 872 // Hack XXX FIX ME !!! 873 // A scavenge may not have been attempted, or may have 874 // been attempted and failed, because the old gen was too full 875 if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker && 876 incremental_collection_will_fail(false /* don't consult_young */)) { 877 if (PrintGCDetails) { 878 gclog_or_tty->print_cr("GC locker: Trying a full collection " 879 "because scavenge failed"); 880 } 881 // This time allow the old gen to be collected as well 882 do_collection(true /* full */, 883 clear_all_soft_refs /* clear_all_soft_refs */, 884 0 /* size */, 885 false /* is_tlab */, 886 1 /* old */ /* max_level */); 887 } 888 } 889 890 bool GenCollectedHeap::is_in_young(oop p) { 891 bool result = ((HeapWord*)p) < _old_gen->reserved().start(); 892 assert(result == _young_gen->is_in_reserved(p), 893 err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p))); 894 return result; 895 } 896 897 // Returns "TRUE" iff "p" points into the committed areas of the heap. 898 bool GenCollectedHeap::is_in(const void* p) const { 899 return _young_gen->is_in(p) || _old_gen->is_in(p); 900 } 901 902 #ifdef ASSERT 903 // Don't implement this by using is_in_young(). This method is used 904 // in some cases to check that is_in_young() is correct. 905 bool GenCollectedHeap::is_in_partial_collection(const void* p) { 906 assert(is_in_reserved(p) || p == NULL, 907 "Does not work if address is non-null and outside of the heap"); 908 return p < _young_gen->reserved().end() && p != NULL; 909 } 910 #endif 911 912 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) { 913 NoHeaderExtendedOopClosure no_header_cl(cl); 914 oop_iterate(&no_header_cl); 915 } 916 917 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 918 _young_gen->oop_iterate(cl); 919 _old_gen->oop_iterate(cl); 920 } 921 922 void GenCollectedHeap::object_iterate(ObjectClosure* cl) { 923 _young_gen->object_iterate(cl); 924 _old_gen->object_iterate(cl); 925 } 926 927 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) { 928 _young_gen->safe_object_iterate(cl); 929 _old_gen->safe_object_iterate(cl); 930 } 931 932 Space* GenCollectedHeap::space_containing(const void* addr) const { 933 Space* res = _young_gen->space_containing(addr); 934 if (res != NULL) { 935 return res; 936 } 937 res = _old_gen->space_containing(addr); 938 assert(res != NULL, "Could not find containing space"); 939 return res; 940 } 941 942 HeapWord* GenCollectedHeap::block_start(const void* addr) const { 943 assert(is_in_reserved(addr), "block_start of address outside of heap"); 944 if (_young_gen->is_in_reserved(addr)) { 945 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 946 return _young_gen->block_start(addr); 947 } 948 949 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 950 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 951 return _old_gen->block_start(addr); 952 } 953 954 size_t GenCollectedHeap::block_size(const HeapWord* addr) const { 955 assert(is_in_reserved(addr), "block_size of address outside of heap"); 956 if (_young_gen->is_in_reserved(addr)) { 957 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 958 return _young_gen->block_size(addr); 959 } 960 961 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 962 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 963 return _old_gen->block_size(addr); 964 } 965 966 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const { 967 assert(is_in_reserved(addr), "block_is_obj of address outside of heap"); 968 assert(block_start(addr) == addr, "addr must be a block start"); 969 if (_young_gen->is_in_reserved(addr)) { 970 return _young_gen->block_is_obj(addr); 971 } 972 973 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 974 return _old_gen->block_is_obj(addr); 975 } 976 977 bool GenCollectedHeap::supports_tlab_allocation() const { 978 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 979 return _young_gen->supports_tlab_allocation(); 980 } 981 982 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const { 983 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 984 if (_young_gen->supports_tlab_allocation()) { 985 return _young_gen->tlab_capacity(); 986 } 987 return 0; 988 } 989 990 size_t GenCollectedHeap::tlab_used(Thread* thr) const { 991 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 992 if (_young_gen->supports_tlab_allocation()) { 993 return _young_gen->tlab_used(); 994 } 995 return 0; 996 } 997 998 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const { 999 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1000 if (_young_gen->supports_tlab_allocation()) { 1001 return _young_gen->unsafe_max_tlab_alloc(); 1002 } 1003 return 0; 1004 } 1005 1006 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) { 1007 bool gc_overhead_limit_was_exceeded; 1008 return collector_policy()->mem_allocate_work(size /* size */, 1009 true /* is_tlab */, 1010 &gc_overhead_limit_was_exceeded); 1011 } 1012 1013 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size 1014 // from the list headed by "*prev_ptr". 1015 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) { 1016 bool first = true; 1017 size_t min_size = 0; // "first" makes this conceptually infinite. 1018 ScratchBlock **smallest_ptr, *smallest; 1019 ScratchBlock *cur = *prev_ptr; 1020 while (cur) { 1021 assert(*prev_ptr == cur, "just checking"); 1022 if (first || cur->num_words < min_size) { 1023 smallest_ptr = prev_ptr; 1024 smallest = cur; 1025 min_size = smallest->num_words; 1026 first = false; 1027 } 1028 prev_ptr = &cur->next; 1029 cur = cur->next; 1030 } 1031 smallest = *smallest_ptr; 1032 *smallest_ptr = smallest->next; 1033 return smallest; 1034 } 1035 1036 // Sort the scratch block list headed by res into decreasing size order, 1037 // and set "res" to the result. 1038 static void sort_scratch_list(ScratchBlock*& list) { 1039 ScratchBlock* sorted = NULL; 1040 ScratchBlock* unsorted = list; 1041 while (unsorted) { 1042 ScratchBlock *smallest = removeSmallestScratch(&unsorted); 1043 smallest->next = sorted; 1044 sorted = smallest; 1045 } 1046 list = sorted; 1047 } 1048 1049 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor, 1050 size_t max_alloc_words) { 1051 ScratchBlock* res = NULL; 1052 _young_gen->contribute_scratch(res, requestor, max_alloc_words); 1053 _old_gen->contribute_scratch(res, requestor, max_alloc_words); 1054 sort_scratch_list(res); 1055 return res; 1056 } 1057 1058 void GenCollectedHeap::release_scratch() { 1059 _young_gen->reset_scratch(); 1060 _old_gen->reset_scratch(); 1061 } 1062 1063 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure { 1064 void do_generation(Generation* gen) { 1065 gen->prepare_for_verify(); 1066 } 1067 }; 1068 1069 void GenCollectedHeap::prepare_for_verify() { 1070 ensure_parsability(false); // no need to retire TLABs 1071 GenPrepareForVerifyClosure blk; 1072 generation_iterate(&blk, false); 1073 } 1074 1075 void GenCollectedHeap::generation_iterate(GenClosure* cl, 1076 bool old_to_young) { 1077 if (old_to_young) { 1078 cl->do_generation(_old_gen); 1079 cl->do_generation(_young_gen); 1080 } else { 1081 cl->do_generation(_young_gen); 1082 cl->do_generation(_old_gen); 1083 } 1084 } 1085 1086 bool GenCollectedHeap::is_maximal_no_gc() const { 1087 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc(); 1088 } 1089 1090 void GenCollectedHeap::save_marks() { 1091 _young_gen->save_marks(); 1092 _old_gen->save_marks(); 1093 } 1094 1095 GenCollectedHeap* GenCollectedHeap::heap() { 1096 CollectedHeap* heap = Universe::heap(); 1097 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()"); 1098 assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Not a GenCollectedHeap"); 1099 return (GenCollectedHeap*)heap; 1100 } 1101 1102 void GenCollectedHeap::prepare_for_compaction() { 1103 // Start by compacting into same gen. 1104 CompactPoint cp(_old_gen); 1105 _old_gen->prepare_for_compaction(&cp); 1106 _young_gen->prepare_for_compaction(&cp); 1107 } 1108 1109 GCStats* GenCollectedHeap::gc_stats(int level) const { 1110 if (level == 0) { 1111 return _young_gen->gc_stats(); 1112 } else { 1113 return _old_gen->gc_stats(); 1114 } 1115 } 1116 1117 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) { 1118 if (!silent) { 1119 gclog_or_tty->print("%s", _old_gen->name()); 1120 gclog_or_tty->print(" "); 1121 } 1122 _old_gen->verify(); 1123 1124 if (!silent) { 1125 gclog_or_tty->print("%s", _young_gen->name()); 1126 gclog_or_tty->print(" "); 1127 } 1128 _young_gen->verify(); 1129 1130 if (!silent) { 1131 gclog_or_tty->print("remset "); 1132 } 1133 rem_set()->verify(); 1134 } 1135 1136 void GenCollectedHeap::print_on(outputStream* st) const { 1137 _young_gen->print_on(st); 1138 _old_gen->print_on(st); 1139 MetaspaceAux::print_on(st); 1140 } 1141 1142 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const { 1143 if (workers() != NULL) { 1144 workers()->threads_do(tc); 1145 } 1146 #if INCLUDE_ALL_GCS 1147 if (UseConcMarkSweepGC) { 1148 ConcurrentMarkSweepThread::threads_do(tc); 1149 } 1150 #endif // INCLUDE_ALL_GCS 1151 } 1152 1153 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const { 1154 #if INCLUDE_ALL_GCS 1155 if (UseConcMarkSweepGC) { 1156 workers()->print_worker_threads_on(st); 1157 ConcurrentMarkSweepThread::print_all_on(st); 1158 } 1159 #endif // INCLUDE_ALL_GCS 1160 } 1161 1162 void GenCollectedHeap::print_on_error(outputStream* st) const { 1163 this->CollectedHeap::print_on_error(st); 1164 1165 #if INCLUDE_ALL_GCS 1166 if (UseConcMarkSweepGC) { 1167 st->cr(); 1168 CMSCollector::print_on_error(st); 1169 } 1170 #endif // INCLUDE_ALL_GCS 1171 } 1172 1173 void GenCollectedHeap::print_tracing_info() const { 1174 if (TraceYoungGenTime) { 1175 _young_gen->print_summary_info(); 1176 } 1177 if (TraceOldGenTime) { 1178 _old_gen->print_summary_info(); 1179 } 1180 } 1181 1182 void GenCollectedHeap::print_heap_change(size_t prev_used) const { 1183 if (PrintGCDetails && Verbose) { 1184 gclog_or_tty->print(" " SIZE_FORMAT 1185 "->" SIZE_FORMAT 1186 "(" SIZE_FORMAT ")", 1187 prev_used, used(), capacity()); 1188 } else { 1189 gclog_or_tty->print(" " SIZE_FORMAT "K" 1190 "->" SIZE_FORMAT "K" 1191 "(" SIZE_FORMAT "K)", 1192 prev_used / K, used() / K, capacity() / K); 1193 } 1194 } 1195 1196 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure { 1197 private: 1198 bool _full; 1199 public: 1200 void do_generation(Generation* gen) { 1201 gen->gc_prologue(_full); 1202 } 1203 GenGCPrologueClosure(bool full) : _full(full) {}; 1204 }; 1205 1206 void GenCollectedHeap::gc_prologue(bool full) { 1207 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 1208 1209 always_do_update_barrier = false; 1210 // Fill TLAB's and such 1211 CollectedHeap::accumulate_statistics_all_tlabs(); 1212 ensure_parsability(true); // retire TLABs 1213 1214 // Walk generations 1215 GenGCPrologueClosure blk(full); 1216 generation_iterate(&blk, false); // not old-to-young. 1217 }; 1218 1219 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure { 1220 private: 1221 bool _full; 1222 public: 1223 void do_generation(Generation* gen) { 1224 gen->gc_epilogue(_full); 1225 } 1226 GenGCEpilogueClosure(bool full) : _full(full) {}; 1227 }; 1228 1229 void GenCollectedHeap::gc_epilogue(bool full) { 1230 #ifdef COMPILER2 1231 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 1232 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr())); 1233 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps"); 1234 #endif /* COMPILER2 */ 1235 1236 resize_all_tlabs(); 1237 1238 GenGCEpilogueClosure blk(full); 1239 generation_iterate(&blk, false); // not old-to-young. 1240 1241 if (!CleanChunkPoolAsync) { 1242 Chunk::clean_chunk_pool(); 1243 } 1244 1245 MetaspaceCounters::update_performance_counters(); 1246 CompressedClassSpaceCounters::update_performance_counters(); 1247 1248 always_do_update_barrier = UseConcMarkSweepGC; 1249 }; 1250 1251 #ifndef PRODUCT 1252 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure { 1253 private: 1254 public: 1255 void do_generation(Generation* gen) { 1256 gen->record_spaces_top(); 1257 } 1258 }; 1259 1260 void GenCollectedHeap::record_gen_tops_before_GC() { 1261 if (ZapUnusedHeapArea) { 1262 GenGCSaveTopsBeforeGCClosure blk; 1263 generation_iterate(&blk, false); // not old-to-young. 1264 } 1265 } 1266 #endif // not PRODUCT 1267 1268 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure { 1269 public: 1270 void do_generation(Generation* gen) { 1271 gen->ensure_parsability(); 1272 } 1273 }; 1274 1275 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) { 1276 CollectedHeap::ensure_parsability(retire_tlabs); 1277 GenEnsureParsabilityClosure ep_cl; 1278 generation_iterate(&ep_cl, false); 1279 } 1280 1281 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen, 1282 oop obj, 1283 size_t obj_size) { 1284 guarantee(old_gen->level() == 1, "We only get here with an old generation"); 1285 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); 1286 HeapWord* result = NULL; 1287 1288 result = old_gen->expand_and_allocate(obj_size, false); 1289 1290 if (result != NULL) { 1291 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size); 1292 } 1293 return oop(result); 1294 } 1295 1296 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure { 1297 jlong _time; // in ms 1298 jlong _now; // in ms 1299 1300 public: 1301 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { } 1302 1303 jlong time() { return _time; } 1304 1305 void do_generation(Generation* gen) { 1306 _time = MIN2(_time, gen->time_of_last_gc(_now)); 1307 } 1308 }; 1309 1310 jlong GenCollectedHeap::millis_since_last_gc() { 1311 // We need a monotonically non-decreasing time in ms but 1312 // os::javaTimeMillis() does not guarantee monotonicity. 1313 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 1314 GenTimeOfLastGCClosure tolgc_cl(now); 1315 // iterate over generations getting the oldest 1316 // time that a generation was collected 1317 generation_iterate(&tolgc_cl, false); 1318 1319 // javaTimeNanos() is guaranteed to be monotonically non-decreasing 1320 // provided the underlying platform provides such a time source 1321 // (and it is bug free). So we still have to guard against getting 1322 // back a time later than 'now'. 1323 jlong retVal = now - tolgc_cl.time(); 1324 if (retVal < 0) { 1325 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);) 1326 return 0; 1327 } 1328 return retVal; 1329 }