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