1 /* 2 * Copyright (c) 2001, 2021, 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 #ifndef SHARE_GC_G1_G1COLLECTEDHEAP_HPP 26 #define SHARE_GC_G1_G1COLLECTEDHEAP_HPP 27 28 #include "gc/g1/g1BarrierSet.hpp" 29 #include "gc/g1/g1BiasedArray.hpp" 30 #include "gc/g1/g1CardTable.hpp" 31 #include "gc/g1/g1CardSet.hpp" 32 #include "gc/g1/g1CollectionSet.hpp" 33 #include "gc/g1/g1CollectorState.hpp" 34 #include "gc/g1/g1ConcurrentMark.hpp" 35 #include "gc/g1/g1EdenRegions.hpp" 36 #include "gc/g1/g1EvacStats.hpp" 37 #include "gc/g1/g1GCPauseType.hpp" 38 #include "gc/g1/g1HeapRegionAttr.hpp" 39 #include "gc/g1/g1HeapTransition.hpp" 40 #include "gc/g1/g1HeapVerifier.hpp" 41 #include "gc/g1/g1HRPrinter.hpp" 42 #include "gc/g1/g1MonitoringSupport.hpp" 43 #include "gc/g1/g1NUMA.hpp" 44 #include "gc/g1/g1SegmentedArrayFreeMemoryTask.hpp" 45 #include "gc/g1/g1SurvivorRegions.hpp" 46 #include "gc/g1/g1YoungGCEvacFailureInjector.hpp" 47 #include "gc/g1/heapRegionManager.hpp" 48 #include "gc/g1/heapRegionSet.hpp" 49 #include "gc/shared/barrierSet.hpp" 50 #include "gc/shared/collectedHeap.hpp" 51 #include "gc/shared/gcHeapSummary.hpp" 52 #include "gc/shared/plab.hpp" 53 #include "gc/shared/softRefPolicy.hpp" 54 #include "gc/shared/taskqueue.hpp" 55 #include "memory/allocation.hpp" 56 #include "memory/iterator.hpp" 57 #include "memory/memRegion.hpp" 58 #include "utilities/bitMap.hpp" 59 60 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 61 // It uses the "Garbage First" heap organization and algorithm, which 62 // may combine concurrent marking with parallel, incremental compaction of 63 // heap subsets that will yield large amounts of garbage. 64 65 // Forward declarations 66 class G1Allocator; 67 class G1ArchiveAllocator; 68 class G1BatchedTask; 69 class G1CardTableEntryClosure; 70 class G1ConcurrentMark; 71 class G1ConcurrentMarkThread; 72 class G1ConcurrentRefine; 73 class G1GCCounters; 74 class G1GCPhaseTimes; 75 class G1HeapSizingPolicy; 76 class G1HotCardCache; 77 class G1NewTracer; 78 class G1RemSet; 79 class G1ServiceTask; 80 class G1ServiceThread; 81 class GCMemoryManager; 82 class HeapRegion; 83 class MemoryPool; 84 class nmethod; 85 class ReferenceProcessor; 86 class STWGCTimer; 87 class WorkerThreads; 88 89 typedef OverflowTaskQueue<ScannerTask, mtGC> G1ScannerTasksQueue; 90 typedef GenericTaskQueueSet<G1ScannerTasksQueue, mtGC> G1ScannerTasksQueueSet; 91 92 typedef int RegionIdx_t; // needs to hold [ 0..max_reserved_regions() ) 93 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 94 95 // The G1 STW is alive closure. 96 // An instance is embedded into the G1CH and used as the 97 // (optional) _is_alive_non_header closure in the STW 98 // reference processor. It is also extensively used during 99 // reference processing during STW evacuation pauses. 100 class G1STWIsAliveClosure : public BoolObjectClosure { 101 G1CollectedHeap* _g1h; 102 public: 103 G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {} 104 bool do_object_b(oop p) override; 105 }; 106 107 class G1STWSubjectToDiscoveryClosure : public BoolObjectClosure { 108 G1CollectedHeap* _g1h; 109 public: 110 G1STWSubjectToDiscoveryClosure(G1CollectedHeap* g1h) : _g1h(g1h) {} 111 bool do_object_b(oop p) override; 112 }; 113 114 class G1RegionMappingChangedListener : public G1MappingChangedListener { 115 private: 116 void reset_from_card_cache(uint start_idx, size_t num_regions); 117 public: 118 void on_commit(uint start_idx, size_t num_regions, bool zero_filled) override; 119 }; 120 121 class G1CollectedHeap : public CollectedHeap { 122 friend class VM_G1CollectForAllocation; 123 friend class VM_G1CollectFull; 124 friend class VM_G1TryInitiateConcMark; 125 friend class VMStructs; 126 friend class MutatorAllocRegion; 127 friend class G1FullCollector; 128 friend class G1GCAllocRegion; 129 friend class G1HeapVerifier; 130 131 friend class G1YoungGCVerifierMark; 132 133 // Closures used in implementation. 134 friend class G1EvacuateRegionsTask; 135 friend class G1PLABAllocator; 136 137 // Other related classes. 138 friend class G1HeapPrinterMark; 139 friend class HeapRegionClaimer; 140 141 // Testing classes. 142 friend class G1CheckRegionAttrTableClosure; 143 144 private: 145 G1ServiceThread* _service_thread; 146 G1ServiceTask* _periodic_gc_task; 147 G1SegmentedArrayFreeMemoryTask* _free_segmented_array_memory_task; 148 149 WorkerThreads* _workers; 150 G1CardTable* _card_table; 151 152 Ticks _collection_pause_end; 153 154 SoftRefPolicy _soft_ref_policy; 155 156 static size_t _humongous_object_threshold_in_words; 157 158 // These sets keep track of old, archive and humongous regions respectively. 159 HeapRegionSet _old_set; 160 HeapRegionSet _archive_set; 161 HeapRegionSet _humongous_set; 162 163 // Young gen memory statistics before GC. 164 G1SegmentedArrayMemoryStats _young_gen_card_set_stats; 165 // Collection set candidates memory statistics after GC. 166 G1SegmentedArrayMemoryStats _collection_set_candidates_card_set_stats; 167 168 // The block offset table for the G1 heap. 169 G1BlockOffsetTable* _bot; 170 171 public: 172 void rebuild_free_region_list(); 173 // Start a new incremental collection set for the next pause. 174 void start_new_collection_set(); 175 176 void prepare_region_for_full_compaction(HeapRegion* hr); 177 178 private: 179 // Rebuilds the region sets / lists so that they are repopulated to 180 // reflect the contents of the heap. The only exception is the 181 // humongous set which was not torn down in the first place. If 182 // free_list_only is true, it will only rebuild the free list. 183 void rebuild_region_sets(bool free_list_only); 184 185 // Callback for region mapping changed events. 186 G1RegionMappingChangedListener _listener; 187 188 // Handle G1 NUMA support. 189 G1NUMA* _numa; 190 191 // The sequence of all heap regions in the heap. 192 HeapRegionManager _hrm; 193 194 // Manages all allocations with regions except humongous object allocations. 195 G1Allocator* _allocator; 196 197 G1YoungGCEvacFailureInjector _evac_failure_injector; 198 199 // Manages all heap verification. 200 G1HeapVerifier* _verifier; 201 202 // Outside of GC pauses, the number of bytes used in all regions other 203 // than the current allocation region(s). 204 volatile size_t _summary_bytes_used; 205 206 void increase_used(size_t bytes); 207 void decrease_used(size_t bytes); 208 209 void set_used(size_t bytes); 210 211 // Number of bytes used in all regions during GC. Typically changed when 212 // retiring a GC alloc region. 213 size_t _bytes_used_during_gc; 214 215 public: 216 size_t bytes_used_during_gc() const { return _bytes_used_during_gc; } 217 218 private: 219 // Class that handles archive allocation ranges. 220 G1ArchiveAllocator* _archive_allocator; 221 222 // GC allocation statistics policy for survivors. 223 G1EvacStats _survivor_evac_stats; 224 225 // GC allocation statistics policy for tenured objects. 226 G1EvacStats _old_evac_stats; 227 228 // Helper for monitoring and management support. 229 G1MonitoringSupport* _monitoring_support; 230 231 // Records whether the region at the given index is (still) a 232 // candidate for eager reclaim. Only valid for humongous start 233 // regions; other regions have unspecified values. Humongous start 234 // regions are initialized at start of collection pause, with 235 // candidates removed from the set as they are found reachable from 236 // roots or the young generation. 237 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 238 protected: 239 bool default_value() const override { return false; } 240 public: 241 void clear() { G1BiasedMappedArray<bool>::clear(); } 242 void set_candidate(uint region, bool value) { 243 set_by_index(region, value); 244 } 245 bool is_candidate(uint region) { 246 return get_by_index(region); 247 } 248 }; 249 250 HumongousReclaimCandidates _humongous_reclaim_candidates; 251 uint _num_humongous_objects; // Current amount of (all) humongous objects found in the heap. 252 uint _num_humongous_reclaim_candidates; // Number of humongous object eager reclaim candidates. 253 public: 254 uint num_humongous_objects() const { return _num_humongous_objects; } 255 uint num_humongous_reclaim_candidates() const { return _num_humongous_reclaim_candidates; } 256 bool has_humongous_reclaim_candidates() const { return _num_humongous_reclaim_candidates > 0; } 257 258 bool should_do_eager_reclaim() const; 259 260 void set_humongous_stats(uint num_humongous_total, uint num_humongous_candidates); 261 262 bool should_sample_collection_set_candidates() const; 263 void set_collection_set_candidates_stats(G1SegmentedArrayMemoryStats& stats); 264 void set_young_gen_card_set_stats(const G1SegmentedArrayMemoryStats& stats); 265 266 private: 267 268 G1HRPrinter _hr_printer; 269 270 // Return true if an explicit GC should start a concurrent cycle instead 271 // of doing a STW full GC. A concurrent cycle should be started if: 272 // (a) cause == _g1_humongous_allocation, 273 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent, 274 // (c) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent, 275 // (d) cause == _wb_conc_mark or _wb_breakpoint, 276 // (e) cause == _g1_periodic_collection and +G1PeriodicGCInvokesConcurrent. 277 bool should_do_concurrent_full_gc(GCCause::Cause cause); 278 279 // Attempt to start a concurrent cycle with the indicated cause. 280 // precondition: should_do_concurrent_full_gc(cause) 281 bool try_collect_concurrently(GCCause::Cause cause, 282 uint gc_counter, 283 uint old_marking_started_before); 284 285 // indicates whether we are in young or mixed GC mode 286 G1CollectorState _collector_state; 287 288 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 289 // concurrent cycles) we have started. 290 volatile uint _old_marking_cycles_started; 291 292 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 293 // concurrent cycles) we have completed. 294 volatile uint _old_marking_cycles_completed; 295 296 // This is a non-product method that is helpful for testing. It is 297 // called at the end of a GC and artificially expands the heap by 298 // allocating a number of dead regions. This way we can induce very 299 // frequent marking cycles and stress the cleanup / concurrent 300 // cleanup code more (as all the regions that will be allocated by 301 // this method will be found dead by the marking cycle). 302 void allocate_dummy_regions() PRODUCT_RETURN; 303 304 // Create a memory mapper for auxiliary data structures of the given size and 305 // translation factor. 306 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 307 size_t size, 308 size_t translation_factor); 309 310 void trace_heap(GCWhen::Type when, const GCTracer* tracer) override; 311 312 // These are macros so that, if the assert fires, we get the correct 313 // line number, file, etc. 314 315 #define heap_locking_asserts_params(_extra_message_) \ 316 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 317 (_extra_message_), \ 318 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 319 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 320 BOOL_TO_STR(Thread::current()->is_VM_thread()) 321 322 #define assert_heap_locked() \ 323 do { \ 324 assert(Heap_lock->owned_by_self(), \ 325 heap_locking_asserts_params("should be holding the Heap_lock")); \ 326 } while (0) 327 328 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 329 do { \ 330 assert(Heap_lock->owned_by_self() || \ 331 (SafepointSynchronize::is_at_safepoint() && \ 332 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 333 heap_locking_asserts_params("should be holding the Heap_lock or " \ 334 "should be at a safepoint")); \ 335 } while (0) 336 337 #define assert_heap_locked_and_not_at_safepoint() \ 338 do { \ 339 assert(Heap_lock->owned_by_self() && \ 340 !SafepointSynchronize::is_at_safepoint(), \ 341 heap_locking_asserts_params("should be holding the Heap_lock and " \ 342 "should not be at a safepoint")); \ 343 } while (0) 344 345 #define assert_heap_not_locked() \ 346 do { \ 347 assert(!Heap_lock->owned_by_self(), \ 348 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 349 } while (0) 350 351 #define assert_heap_not_locked_and_not_at_safepoint() \ 352 do { \ 353 assert(!Heap_lock->owned_by_self() && \ 354 !SafepointSynchronize::is_at_safepoint(), \ 355 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 356 "should not be at a safepoint")); \ 357 } while (0) 358 359 #define assert_at_safepoint_on_vm_thread() \ 360 do { \ 361 assert_at_safepoint(); \ 362 assert(Thread::current_or_null() != NULL, "no current thread"); \ 363 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \ 364 } while (0) 365 366 #ifdef ASSERT 367 #define assert_used_and_recalculate_used_equal(g1h) \ 368 do { \ 369 size_t cur_used_bytes = g1h->used(); \ 370 size_t recal_used_bytes = g1h->recalculate_used(); \ 371 assert(cur_used_bytes == recal_used_bytes, "Used(" SIZE_FORMAT ") is not" \ 372 " same as recalculated used(" SIZE_FORMAT ").", \ 373 cur_used_bytes, recal_used_bytes); \ 374 } while (0) 375 #else 376 #define assert_used_and_recalculate_used_equal(g1h) do {} while(0) 377 #endif 378 379 // The young region list. 380 G1EdenRegions _eden; 381 G1SurvivorRegions _survivor; 382 383 STWGCTimer* _gc_timer_stw; 384 385 G1NewTracer* _gc_tracer_stw; 386 387 // The current policy object for the collector. 388 G1Policy* _policy; 389 G1HeapSizingPolicy* _heap_sizing_policy; 390 391 G1CollectionSet _collection_set; 392 393 // Try to allocate a single non-humongous HeapRegion sufficient for 394 // an allocation of the given word_size. If do_expand is true, 395 // attempt to expand the heap if necessary to satisfy the allocation 396 // request. 'type' takes the type of region to be allocated. (Use constants 397 // Old, Eden, Humongous, Survivor defined in HeapRegionType.) 398 HeapRegion* new_region(size_t word_size, 399 HeapRegionType type, 400 bool do_expand, 401 uint node_index = G1NUMA::AnyNodeIndex); 402 403 // Initialize a contiguous set of free regions of length num_regions 404 // and starting at index first so that they appear as a single 405 // humongous region. 406 HeapWord* humongous_obj_allocate_initialize_regions(HeapRegion* first_hr, 407 uint num_regions, 408 size_t word_size); 409 410 // Attempt to allocate a humongous object of the given size. Return 411 // NULL if unsuccessful. 412 HeapWord* humongous_obj_allocate(size_t word_size); 413 414 // The following two methods, allocate_new_tlab() and 415 // mem_allocate(), are the two main entry points from the runtime 416 // into the G1's allocation routines. They have the following 417 // assumptions: 418 // 419 // * They should both be called outside safepoints. 420 // 421 // * They should both be called without holding the Heap_lock. 422 // 423 // * All allocation requests for new TLABs should go to 424 // allocate_new_tlab(). 425 // 426 // * All non-TLAB allocation requests should go to mem_allocate(). 427 // 428 // * If either call cannot satisfy the allocation request using the 429 // current allocating region, they will try to get a new one. If 430 // this fails, they will attempt to do an evacuation pause and 431 // retry the allocation. 432 // 433 // * If all allocation attempts fail, even after trying to schedule 434 // an evacuation pause, allocate_new_tlab() will return NULL, 435 // whereas mem_allocate() will attempt a heap expansion and/or 436 // schedule a Full GC. 437 // 438 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 439 // should never be called with word_size being humongous. All 440 // humongous allocation requests should go to mem_allocate() which 441 // will satisfy them with a special path. 442 443 HeapWord* allocate_new_tlab(size_t min_size, 444 size_t requested_size, 445 size_t* actual_size) override; 446 447 HeapWord* mem_allocate(size_t word_size, 448 bool* gc_overhead_limit_was_exceeded) override; 449 450 // First-level mutator allocation attempt: try to allocate out of 451 // the mutator alloc region without taking the Heap_lock. This 452 // should only be used for non-humongous allocations. 453 inline HeapWord* attempt_allocation(size_t min_word_size, 454 size_t desired_word_size, 455 size_t* actual_word_size); 456 457 // Second-level mutator allocation attempt: take the Heap_lock and 458 // retry the allocation attempt, potentially scheduling a GC 459 // pause. This should only be used for non-humongous allocations. 460 HeapWord* attempt_allocation_slow(size_t word_size); 461 462 // Takes the Heap_lock and attempts a humongous allocation. It can 463 // potentially schedule a GC pause. 464 HeapWord* attempt_allocation_humongous(size_t word_size); 465 466 // Allocation attempt that should be called during safepoints (e.g., 467 // at the end of a successful GC). expect_null_mutator_alloc_region 468 // specifies whether the mutator alloc region is expected to be NULL 469 // or not. 470 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 471 bool expect_null_mutator_alloc_region); 472 473 // These methods are the "callbacks" from the G1AllocRegion class. 474 475 // For mutator alloc regions. 476 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force, uint node_index); 477 void retire_mutator_alloc_region(HeapRegion* alloc_region, 478 size_t allocated_bytes); 479 480 // For GC alloc regions. 481 bool has_more_regions(G1HeapRegionAttr dest); 482 HeapRegion* new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index); 483 void retire_gc_alloc_region(HeapRegion* alloc_region, 484 size_t allocated_bytes, G1HeapRegionAttr dest); 485 486 // - if explicit_gc is true, the GC is for a System.gc() etc, 487 // otherwise it's for a failed allocation. 488 // - if clear_all_soft_refs is true, all soft references should be 489 // cleared during the GC. 490 // - if do_maximal_compaction is true, full gc will do a maximally 491 // compacting collection, leaving no dead wood. 492 // - it returns false if it is unable to do the collection due to the 493 // GC locker being active, true otherwise. 494 bool do_full_collection(bool explicit_gc, 495 bool clear_all_soft_refs, 496 bool do_maximal_compaction); 497 498 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 499 void do_full_collection(bool clear_all_soft_refs) override; 500 501 // Helper to do a full collection that clears soft references. 502 bool upgrade_to_full_collection(); 503 504 // Callback from VM_G1CollectForAllocation operation. 505 // This function does everything necessary/possible to satisfy a 506 // failed allocation request (including collection, expansion, etc.) 507 HeapWord* satisfy_failed_allocation(size_t word_size, 508 bool* succeeded); 509 // Internal helpers used during full GC to split it up to 510 // increase readability. 511 void abort_concurrent_cycle(); 512 void verify_before_full_collection(bool explicit_gc); 513 void prepare_heap_for_full_collection(); 514 void prepare_heap_for_mutators(); 515 void abort_refinement(); 516 void verify_after_full_collection(); 517 void print_heap_after_full_collection(); 518 519 // Helper method for satisfy_failed_allocation() 520 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 521 bool do_gc, 522 bool maximal_compaction, 523 bool expect_null_mutator_alloc_region, 524 bool* gc_succeeded); 525 526 // Attempting to expand the heap sufficiently 527 // to support an allocation of the given "word_size". If 528 // successful, perform the allocation and return the address of the 529 // allocated block, or else "NULL". 530 HeapWord* expand_and_allocate(size_t word_size); 531 532 void verify_numa_regions(const char* desc); 533 534 public: 535 // If during a concurrent start pause we may install a pending list head which is not 536 // otherwise reachable, ensure that it is marked in the bitmap for concurrent marking 537 // to discover. 538 void make_pending_list_reachable(); 539 540 G1ServiceThread* service_thread() const { return _service_thread; } 541 542 WorkerThreads* workers() const { return _workers; } 543 544 // Run the given batch task using the workers. 545 void run_batch_task(G1BatchedTask* cl); 546 547 G1Allocator* allocator() { 548 return _allocator; 549 } 550 551 G1YoungGCEvacFailureInjector* evac_failure_injector() { return &_evac_failure_injector; } 552 553 G1HeapVerifier* verifier() { 554 return _verifier; 555 } 556 557 G1MonitoringSupport* monitoring_support() { 558 assert(_monitoring_support != nullptr, "should have been initialized"); 559 return _monitoring_support; 560 } 561 562 void resize_heap_if_necessary(); 563 564 // Check if there is memory to uncommit and if so schedule a task to do it. 565 void uncommit_regions_if_necessary(); 566 // Immediately uncommit uncommittable regions. 567 uint uncommit_regions(uint region_limit); 568 bool has_uncommittable_regions(); 569 570 G1NUMA* numa() const { return _numa; } 571 572 // Expand the garbage-first heap by at least the given size (in bytes!). 573 // Returns true if the heap was expanded by the requested amount; 574 // false otherwise. 575 // (Rounds up to a HeapRegion boundary.) 576 bool expand(size_t expand_bytes, WorkerThreads* pretouch_workers = NULL, double* expand_time_ms = NULL); 577 bool expand_single_region(uint node_index); 578 579 // Returns the PLAB statistics for a given destination. 580 inline G1EvacStats* alloc_buffer_stats(G1HeapRegionAttr dest); 581 582 // Determines PLAB size for a given destination. 583 inline size_t desired_plab_sz(G1HeapRegionAttr dest); 584 585 // Do anything common to GC's. 586 void gc_prologue(bool full); 587 void gc_epilogue(bool full); 588 589 // Does the given region fulfill remembered set based eager reclaim candidate requirements? 590 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const; 591 592 // Modify the reclaim candidate set and test for presence. 593 // These are only valid for starts_humongous regions. 594 inline void set_humongous_reclaim_candidate(uint region, bool value); 595 inline bool is_humongous_reclaim_candidate(uint region); 596 597 // Remove from the reclaim candidate set. Also remove from the 598 // collection set so that later encounters avoid the slow path. 599 inline void set_humongous_is_live(oop obj); 600 601 // Register the given region to be part of the collection set. 602 inline void register_humongous_region_with_region_attr(uint index); 603 604 // We register a region with the fast "in collection set" test. We 605 // simply set to true the array slot corresponding to this region. 606 void register_young_region_with_region_attr(HeapRegion* r) { 607 _region_attr.set_in_young(r->hrm_index()); 608 } 609 inline void register_new_survivor_region_with_region_attr(HeapRegion* r); 610 inline void register_region_with_region_attr(HeapRegion* r); 611 inline void register_old_region_with_region_attr(HeapRegion* r); 612 inline void register_optional_region_with_region_attr(HeapRegion* r); 613 614 void clear_region_attr(const HeapRegion* hr) { 615 _region_attr.clear(hr); 616 } 617 618 void clear_region_attr() { 619 _region_attr.clear(); 620 } 621 622 // Verify that the G1RegionAttr remset tracking corresponds to actual remset tracking 623 // for all regions. 624 void verify_region_attr_remset_is_tracked() PRODUCT_RETURN; 625 626 void clear_prev_bitmap_for_region(HeapRegion* hr); 627 628 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 629 630 // This is called at the start of either a concurrent cycle or a Full 631 // GC to update the number of old marking cycles started. 632 void increment_old_marking_cycles_started(); 633 634 // This is called at the end of either a concurrent cycle or a Full 635 // GC to update the number of old marking cycles completed. Those two 636 // can happen in a nested fashion, i.e., we start a concurrent 637 // cycle, a Full GC happens half-way through it which ends first, 638 // and then the cycle notices that a Full GC happened and ends 639 // too. The concurrent parameter is a boolean to help us do a bit 640 // tighter consistency checking in the method. If concurrent is 641 // false, the caller is the inner caller in the nesting (i.e., the 642 // Full GC). If concurrent is true, the caller is the outer caller 643 // in this nesting (i.e., the concurrent cycle). Further nesting is 644 // not currently supported. The end of this call also notifies 645 // the G1OldGCCount_lock in case a Java thread is waiting for a full 646 // GC to happen (e.g., it called System.gc() with 647 // +ExplicitGCInvokesConcurrent). 648 // whole_heap_examined should indicate that during that old marking 649 // cycle the whole heap has been examined for live objects (as opposed 650 // to only parts, or aborted before completion). 651 void increment_old_marking_cycles_completed(bool concurrent, bool whole_heap_examined); 652 653 uint old_marking_cycles_started() const { 654 return _old_marking_cycles_started; 655 } 656 657 uint old_marking_cycles_completed() const { 658 return _old_marking_cycles_completed; 659 } 660 661 G1HRPrinter* hr_printer() { return &_hr_printer; } 662 663 // Allocates a new heap region instance. 664 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 665 666 // Allocate the highest free region in the reserved heap. This will commit 667 // regions as necessary. 668 HeapRegion* alloc_highest_free_region(); 669 670 // Frees a region by resetting its metadata and adding it to the free list 671 // passed as a parameter (this is usually a local list which will be appended 672 // to the master free list later or NULL if free list management is handled 673 // in another way). 674 // Callers must ensure they are the only one calling free on the given region 675 // at the same time. 676 void free_region(HeapRegion* hr, FreeRegionList* free_list); 677 678 // It dirties the cards that cover the block so that the post 679 // write barrier never queues anything when updating objects on this 680 // block. It is assumed (and in fact we assert) that the block 681 // belongs to a young region. 682 inline void dirty_young_block(HeapWord* start, size_t word_size); 683 684 // Frees a humongous region by collapsing it into individual regions 685 // and calling free_region() for each of them. The freed regions 686 // will be added to the free list that's passed as a parameter (this 687 // is usually a local list which will be appended to the master free 688 // list later). 689 // The method assumes that only a single thread is ever calling 690 // this for a particular region at once. 691 void free_humongous_region(HeapRegion* hr, 692 FreeRegionList* free_list); 693 694 // Facility for allocating in 'archive' regions in high heap memory and 695 // recording the allocated ranges. These should all be called from the 696 // VM thread at safepoints, without the heap lock held. They can be used 697 // to create and archive a set of heap regions which can be mapped at the 698 // same fixed addresses in a subsequent JVM invocation. 699 void begin_archive_alloc_range(bool open = false); 700 701 // Check if the requested size would be too large for an archive allocation. 702 bool is_archive_alloc_too_large(size_t word_size); 703 704 // Allocate memory of the requested size from the archive region. This will 705 // return NULL if the size is too large or if no memory is available. It 706 // does not trigger a garbage collection. 707 HeapWord* archive_mem_allocate(size_t word_size); 708 709 // Optionally aligns the end address and returns the allocated ranges in 710 // an array of MemRegions in order of ascending addresses. 711 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 712 size_t end_alignment_in_bytes = 0); 713 714 // Facility for allocating a fixed range within the heap and marking 715 // the containing regions as 'archive'. For use at JVM init time, when the 716 // caller may mmap archived heap data at the specified range(s). 717 // Verify that the MemRegions specified in the argument array are within the 718 // reserved heap. 719 bool check_archive_addresses(MemRegion* range, size_t count); 720 721 // Commit the appropriate G1 regions containing the specified MemRegions 722 // and mark them as 'archive' regions. The regions in the array must be 723 // non-overlapping and in order of ascending address. 724 bool alloc_archive_regions(MemRegion* range, size_t count, bool open); 725 726 // Insert any required filler objects in the G1 regions around the specified 727 // ranges to make the regions parseable. This must be called after 728 // alloc_archive_regions, and after class loading has occurred. 729 void fill_archive_regions(MemRegion* range, size_t count); 730 731 // Populate the G1BlockOffsetTablePart for archived regions with the given 732 // memory ranges. 733 void populate_archive_regions_bot_part(MemRegion* range, size_t count); 734 735 // For each of the specified MemRegions, uncommit the containing G1 regions 736 // which had been allocated by alloc_archive_regions. This should be called 737 // rather than fill_archive_regions at JVM init time if the archive file 738 // mapping failed, with the same non-overlapping and sorted MemRegion array. 739 void dealloc_archive_regions(MemRegion* range, size_t count); 740 741 private: 742 743 // Shrink the garbage-first heap by at most the given size (in bytes!). 744 // (Rounds down to a HeapRegion boundary.) 745 void shrink(size_t shrink_bytes); 746 void shrink_helper(size_t expand_bytes); 747 748 // Schedule the VM operation that will do an evacuation pause to 749 // satisfy an allocation request of word_size. *succeeded will 750 // return whether the VM operation was successful (it did do an 751 // evacuation pause) or not (another thread beat us to it or the GC 752 // locker was active). Given that we should not be holding the 753 // Heap_lock when we enter this method, we will pass the 754 // gc_count_before (i.e., total_collections()) as a parameter since 755 // it has to be read while holding the Heap_lock. Currently, both 756 // methods that call do_collection_pause() release the Heap_lock 757 // before the call, so it's easy to read gc_count_before just before. 758 HeapWord* do_collection_pause(size_t word_size, 759 uint gc_count_before, 760 bool* succeeded, 761 GCCause::Cause gc_cause); 762 763 // Perform an incremental collection at a safepoint, possibly 764 // followed by a by-policy upgrade to a full collection. Returns 765 // false if unable to do the collection due to the GC locker being 766 // active, true otherwise. 767 // precondition: at safepoint on VM thread 768 // precondition: !is_gc_active() 769 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 770 771 // Helper for do_collection_pause_at_safepoint, containing the guts 772 // of the incremental collection pause, executed by the vm thread. 773 void do_collection_pause_at_safepoint_helper(double target_pause_time_ms); 774 775 G1HeapVerifier::G1VerifyType young_collection_verify_type() const; 776 void verify_before_young_collection(G1HeapVerifier::G1VerifyType type); 777 void verify_after_young_collection(G1HeapVerifier::G1VerifyType type); 778 779 public: 780 // Start a concurrent cycle. 781 void start_concurrent_cycle(bool concurrent_operation_is_full_mark); 782 783 void prepare_tlabs_for_mutator(); 784 785 void retire_tlabs(); 786 787 void expand_heap_after_young_collection(); 788 // Update object copying statistics. 789 void record_obj_copy_mem_stats(); 790 791 private: 792 // The hot card cache for remembered set insertion optimization. 793 G1HotCardCache* _hot_card_cache; 794 795 // The g1 remembered set of the heap. 796 G1RemSet* _rem_set; 797 // Global card set configuration 798 G1CardSetConfiguration _card_set_config; 799 800 public: 801 // After a collection pause, reset eden and the collection set. 802 void clear_eden(); 803 void clear_collection_set(); 804 805 // Abandon the current collection set without recording policy 806 // statistics or updating free lists. 807 void abandon_collection_set(G1CollectionSet* collection_set); 808 809 // The concurrent marker (and the thread it runs in.) 810 G1ConcurrentMark* _cm; 811 G1ConcurrentMarkThread* _cm_thread; 812 813 // The concurrent refiner. 814 G1ConcurrentRefine* _cr; 815 816 // The parallel task queues 817 G1ScannerTasksQueueSet *_task_queues; 818 819 // ("Weak") Reference processing support. 820 // 821 // G1 has 2 instances of the reference processor class. 822 // 823 // One (_ref_processor_cm) handles reference object discovery and subsequent 824 // processing during concurrent marking cycles. Discovery is enabled/disabled 825 // at the start/end of a concurrent marking cycle. 826 // 827 // The other (_ref_processor_stw) handles reference object discovery and 828 // processing during incremental evacuation pauses and full GC pauses. 829 // 830 // ## Incremental evacuation pauses 831 // 832 // STW ref processor discovery is enabled/disabled at the start/end of an 833 // incremental evacuation pause. No particular handling of the CM ref 834 // processor is needed, apart from treating the discovered references as 835 // roots; CM discovery does not need to be temporarily disabled as all 836 // marking threads are paused during incremental evacuation pauses. 837 // 838 // ## Full GC pauses 839 // 840 // We abort any ongoing concurrent marking cycle, disable CM discovery, and 841 // temporarily substitute a new closure for the STW ref processor's 842 // _is_alive_non_header field (old value is restored after the full GC). Then 843 // STW ref processor discovery is enabled, and marking & compaction 844 // commences. 845 846 // The (stw) reference processor... 847 ReferenceProcessor* _ref_processor_stw; 848 849 // During reference object discovery, the _is_alive_non_header 850 // closure (if non-null) is applied to the referent object to 851 // determine whether the referent is live. If so then the 852 // reference object does not need to be 'discovered' and can 853 // be treated as a regular oop. This has the benefit of reducing 854 // the number of 'discovered' reference objects that need to 855 // be processed. 856 // 857 // Instance of the is_alive closure for embedding into the 858 // STW reference processor as the _is_alive_non_header field. 859 // Supplying a value for the _is_alive_non_header field is 860 // optional but doing so prevents unnecessary additions to 861 // the discovered lists during reference discovery. 862 G1STWIsAliveClosure _is_alive_closure_stw; 863 864 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw; 865 866 // The (concurrent marking) reference processor... 867 ReferenceProcessor* _ref_processor_cm; 868 869 // Instance of the concurrent mark is_alive closure for embedding 870 // into the Concurrent Marking reference processor as the 871 // _is_alive_non_header field. Supplying a value for the 872 // _is_alive_non_header field is optional but doing so prevents 873 // unnecessary additions to the discovered lists during reference 874 // discovery. 875 G1CMIsAliveClosure _is_alive_closure_cm; 876 877 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm; 878 public: 879 880 G1ScannerTasksQueueSet* task_queues() const; 881 G1ScannerTasksQueue* task_queue(uint i) const; 882 883 // Create a G1CollectedHeap. 884 // Must call the initialize method afterwards. 885 // May not return if something goes wrong. 886 G1CollectedHeap(); 887 888 private: 889 jint initialize_concurrent_refinement(); 890 jint initialize_service_thread(); 891 public: 892 // Initialize the G1CollectedHeap to have the initial and 893 // maximum sizes and remembered and barrier sets 894 // specified by the policy object. 895 jint initialize() override; 896 897 // Returns whether concurrent mark threads (and the VM) are about to terminate. 898 bool concurrent_mark_is_terminating() const; 899 900 void stop() override; 901 void safepoint_synchronize_begin() override; 902 void safepoint_synchronize_end() override; 903 904 // Does operations required after initialization has been done. 905 void post_initialize() override; 906 907 // Initialize weak reference processing. 908 void ref_processing_init(); 909 910 Name kind() const override { 911 return CollectedHeap::G1; 912 } 913 914 const char* name() const override { 915 return "G1"; 916 } 917 918 const G1CollectorState* collector_state() const { return &_collector_state; } 919 G1CollectorState* collector_state() { return &_collector_state; } 920 921 // The current policy object for the collector. 922 G1Policy* policy() const { return _policy; } 923 // The remembered set. 924 G1RemSet* rem_set() const { return _rem_set; } 925 926 inline G1GCPhaseTimes* phase_times() const; 927 928 const G1CollectionSet* collection_set() const { return &_collection_set; } 929 G1CollectionSet* collection_set() { return &_collection_set; } 930 931 SoftRefPolicy* soft_ref_policy() override; 932 933 void initialize_serviceability() override; 934 MemoryUsage memory_usage() override; 935 GrowableArray<GCMemoryManager*> memory_managers() override; 936 GrowableArray<MemoryPool*> memory_pools() override; 937 938 void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) override; 939 940 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 941 void iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id); 942 943 // The shared block offset table array. 944 G1BlockOffsetTable* bot() const { return _bot; } 945 946 // Reference Processing accessors 947 948 // The STW reference processor.... 949 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 950 951 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 952 STWGCTimer* gc_timer_stw() const { return _gc_timer_stw; } 953 954 // The Concurrent Marking reference processor... 955 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 956 957 size_t unused_committed_regions_in_bytes() const; 958 959 size_t capacity() const override; 960 size_t used() const override; 961 // This should be called when we're not holding the heap lock. The 962 // result might be a bit inaccurate. 963 size_t used_unlocked() const; 964 size_t recalculate_used() const; 965 966 // These virtual functions do the actual allocation. 967 // Some heaps may offer a contiguous region for shared non-blocking 968 // allocation, via inlined code (by exporting the address of the top and 969 // end fields defining the extent of the contiguous allocation region.) 970 // But G1CollectedHeap doesn't yet support this. 971 972 bool is_maximal_no_gc() const override { 973 return _hrm.available() == 0; 974 } 975 976 // Returns true if an incremental GC should be upgrade to a full gc. This 977 // is done when there are no free regions and the heap can't be expanded. 978 bool should_upgrade_to_full_gc() const { 979 return is_maximal_no_gc() && num_free_regions() == 0; 980 } 981 982 // The current number of regions in the heap. 983 uint num_regions() const { return _hrm.length(); } 984 985 // The max number of regions reserved for the heap. Except for static array 986 // sizing purposes you probably want to use max_regions(). 987 uint max_reserved_regions() const { return _hrm.reserved_length(); } 988 989 // Max number of regions that can be committed. 990 uint max_regions() const { return _hrm.max_length(); } 991 992 // The number of regions that are completely free. 993 uint num_free_regions() const { return _hrm.num_free_regions(); } 994 995 // The number of regions that can be allocated into. 996 uint num_free_or_available_regions() const { return num_free_regions() + _hrm.available(); } 997 998 MemoryUsage get_auxiliary_data_memory_usage() const { 999 return _hrm.get_auxiliary_data_memory_usage(); 1000 } 1001 1002 // The number of regions that are not completely free. 1003 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1004 1005 #ifdef ASSERT 1006 bool is_on_master_free_list(HeapRegion* hr) { 1007 return _hrm.is_free(hr); 1008 } 1009 #endif // ASSERT 1010 1011 inline void old_set_add(HeapRegion* hr); 1012 inline void old_set_remove(HeapRegion* hr); 1013 1014 inline void archive_set_add(HeapRegion* hr); 1015 1016 size_t non_young_capacity_bytes() { 1017 return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes; 1018 } 1019 1020 // Determine whether the given region is one that we are using as an 1021 // old GC alloc region. 1022 bool is_old_gc_alloc_region(HeapRegion* hr); 1023 1024 // Perform a collection of the heap; intended for use in implementing 1025 // "System.gc". This probably implies as full a collection as the 1026 // "CollectedHeap" supports. 1027 void collect(GCCause::Cause cause) override; 1028 1029 // Perform a collection of the heap with the given cause. 1030 // Returns whether this collection actually executed. 1031 bool try_collect(GCCause::Cause cause, const G1GCCounters& counters_before); 1032 1033 void start_concurrent_gc_for_metadata_allocation(GCCause::Cause gc_cause); 1034 1035 void remove_from_old_gen_sets(const uint old_regions_removed, 1036 const uint archive_regions_removed, 1037 const uint humongous_regions_removed); 1038 void prepend_to_freelist(FreeRegionList* list); 1039 void decrement_summary_bytes(size_t bytes); 1040 1041 bool is_in(const void* p) const override; 1042 1043 // Return "TRUE" iff the given object address is within the collection 1044 // set. Assumes that the reference points into the heap. 1045 inline bool is_in_cset(const HeapRegion *hr); 1046 inline bool is_in_cset(oop obj); 1047 inline bool is_in_cset(HeapWord* addr); 1048 1049 inline bool is_in_cset_or_humongous(const oop obj); 1050 1051 private: 1052 // This array is used for a quick test on whether a reference points into 1053 // the collection set or not. Each of the array's elements denotes whether the 1054 // corresponding region is in the collection set or not. 1055 G1HeapRegionAttrBiasedMappedArray _region_attr; 1056 1057 public: 1058 1059 inline G1HeapRegionAttr region_attr(const void* obj) const; 1060 inline G1HeapRegionAttr region_attr(uint idx) const; 1061 1062 MemRegion reserved() const { 1063 return _hrm.reserved(); 1064 } 1065 1066 bool is_in_reserved(const void* addr) const { 1067 return reserved().contains(addr); 1068 } 1069 1070 G1HotCardCache* hot_card_cache() const { return _hot_card_cache; } 1071 1072 G1CardTable* card_table() const { 1073 return _card_table; 1074 } 1075 1076 // Iteration functions. 1077 1078 void object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer); 1079 1080 // Iterate over all objects, calling "cl.do_object" on each. 1081 void object_iterate(ObjectClosure* cl) override; 1082 1083 ParallelObjectIteratorImpl* parallel_object_iterator(uint thread_num) override; 1084 1085 // Keep alive an object that was loaded with AS_NO_KEEPALIVE. 1086 void keep_alive(oop obj) override; 1087 1088 // Iterate over heap regions, in address order, terminating the 1089 // iteration early if the "do_heap_region" method returns "true". 1090 void heap_region_iterate(HeapRegionClosure* blk) const; 1091 1092 // Return the region with the given index. It assumes the index is valid. 1093 inline HeapRegion* region_at(uint index) const; 1094 inline HeapRegion* region_at_or_null(uint index) const; 1095 1096 // Return the next region (by index) that is part of the same 1097 // humongous object that hr is part of. 1098 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1099 1100 // Calculate the region index of the given address. Given address must be 1101 // within the heap. 1102 inline uint addr_to_region(HeapWord* addr) const; 1103 1104 inline HeapWord* bottom_addr_for_region(uint index) const; 1105 1106 // Two functions to iterate over the heap regions in parallel. Threads 1107 // compete using the HeapRegionClaimer to claim the regions before 1108 // applying the closure on them. 1109 // The _from_worker_offset version uses the HeapRegionClaimer and 1110 // the worker id to calculate a start offset to prevent all workers to 1111 // start from the point. 1112 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 1113 HeapRegionClaimer* hrclaimer, 1114 uint worker_id) const; 1115 1116 void heap_region_par_iterate_from_start(HeapRegionClosure* cl, 1117 HeapRegionClaimer* hrclaimer) const; 1118 1119 // Iterate over all regions in the collection set in parallel. 1120 void collection_set_par_iterate_all(HeapRegionClosure* cl, 1121 HeapRegionClaimer* hr_claimer, 1122 uint worker_id); 1123 1124 // Iterate over all regions currently in the current collection set. 1125 void collection_set_iterate_all(HeapRegionClosure* blk); 1126 1127 // Iterate over the regions in the current increment of the collection set. 1128 // Starts the iteration so that the start regions of a given worker id over the 1129 // set active_workers are evenly spread across the set of collection set regions 1130 // to be iterated. 1131 // The variant with the HeapRegionClaimer guarantees that the closure will be 1132 // applied to a particular region exactly once. 1133 void collection_set_iterate_increment_from(HeapRegionClosure *blk, uint worker_id) { 1134 collection_set_iterate_increment_from(blk, NULL, worker_id); 1135 } 1136 void collection_set_iterate_increment_from(HeapRegionClosure *blk, HeapRegionClaimer* hr_claimer, uint worker_id); 1137 // Iterate over the array of region indexes, uint regions[length], applying 1138 // the given HeapRegionClosure on each region. The worker_id will determine where 1139 // to start the iteration to allow for more efficient parallel iteration. 1140 void par_iterate_regions_array(HeapRegionClosure* cl, 1141 HeapRegionClaimer* hr_claimer, 1142 const uint regions[], 1143 size_t length, 1144 uint worker_id) const; 1145 1146 // Returns the HeapRegion that contains addr. addr must not be NULL. 1147 template <class T> 1148 inline HeapRegion* heap_region_containing(const T addr) const; 1149 1150 // Returns the HeapRegion that contains addr, or NULL if that is an uncommitted 1151 // region. addr must not be NULL. 1152 template <class T> 1153 inline HeapRegion* heap_region_containing_or_null(const T addr) const; 1154 1155 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1156 // each address in the (reserved) heap is a member of exactly 1157 // one block. The defining characteristic of a block is that it is 1158 // possible to find its size, and thus to progress forward to the next 1159 // block. (Blocks may be of different sizes.) Thus, blocks may 1160 // represent Java objects, or they might be free blocks in a 1161 // free-list-based heap (or subheap), as long as the two kinds are 1162 // distinguishable and the size of each is determinable. 1163 1164 // Returns the address of the start of the "block" that contains the 1165 // address "addr". We say "blocks" instead of "object" since some heaps 1166 // may not pack objects densely; a chunk may either be an object or a 1167 // non-object. 1168 HeapWord* block_start(const void* addr) const; 1169 1170 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1171 // the block is an object. 1172 bool block_is_obj(const HeapWord* addr) const; 1173 1174 // Section on thread-local allocation buffers (TLABs) 1175 // See CollectedHeap for semantics. 1176 1177 size_t tlab_capacity(Thread* ignored) const override; 1178 size_t tlab_used(Thread* ignored) const override; 1179 size_t max_tlab_size() const override; 1180 size_t unsafe_max_tlab_alloc(Thread* ignored) const override; 1181 1182 inline bool is_in_young(const oop obj) const; 1183 1184 // Returns "true" iff the given word_size is "very large". 1185 static bool is_humongous(size_t word_size) { 1186 // Note this has to be strictly greater-than as the TLABs 1187 // are capped at the humongous threshold and we want to 1188 // ensure that we don't try to allocate a TLAB as 1189 // humongous and that we don't allocate a humongous 1190 // object in a TLAB. 1191 return word_size > _humongous_object_threshold_in_words; 1192 } 1193 1194 // Returns the humongous threshold for a specific region size 1195 static size_t humongous_threshold_for(size_t region_size) { 1196 return (region_size / 2); 1197 } 1198 1199 // Returns the number of regions the humongous object of the given word size 1200 // requires. 1201 static size_t humongous_obj_size_in_regions(size_t word_size); 1202 1203 // Print the maximum heap capacity. 1204 size_t max_capacity() const override; 1205 1206 Tickspan time_since_last_collection() const { return Ticks::now() - _collection_pause_end; } 1207 1208 // Convenience function to be used in situations where the heap type can be 1209 // asserted to be this type. 1210 static G1CollectedHeap* heap() { 1211 return named_heap<G1CollectedHeap>(CollectedHeap::G1); 1212 } 1213 1214 void set_region_short_lived_locked(HeapRegion* hr); 1215 // add appropriate methods for any other surv rate groups 1216 1217 G1SurvivorRegions* survivor() { return &_survivor; } 1218 1219 uint eden_regions_count() const { return _eden.length(); } 1220 uint eden_regions_count(uint node_index) const { return _eden.regions_on_node(node_index); } 1221 uint survivor_regions_count() const { return _survivor.length(); } 1222 uint survivor_regions_count(uint node_index) const { return _survivor.regions_on_node(node_index); } 1223 size_t eden_regions_used_bytes() const { return _eden.used_bytes(); } 1224 size_t survivor_regions_used_bytes() const { return _survivor.used_bytes(); } 1225 uint young_regions_count() const { return _eden.length() + _survivor.length(); } 1226 uint old_regions_count() const { return _old_set.length(); } 1227 uint archive_regions_count() const { return _archive_set.length(); } 1228 uint humongous_regions_count() const { return _humongous_set.length(); } 1229 1230 #ifdef ASSERT 1231 bool check_young_list_empty(); 1232 #endif 1233 1234 bool is_marked_next(oop obj) const; 1235 1236 // Determine if an object is dead, given the object and also 1237 // the region to which the object belongs. 1238 inline bool is_obj_dead(const oop obj, const HeapRegion* hr) const; 1239 1240 // Determine if an object is dead, given only the object itself. 1241 // This will find the region to which the object belongs and 1242 // then call the region version of the same function. 1243 1244 // Added if it is NULL it isn't dead. 1245 1246 inline bool is_obj_dead(const oop obj) const; 1247 1248 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const; 1249 inline bool is_obj_dead_full(const oop obj) const; 1250 1251 // Mark the live object that failed evacuation in the prev bitmap. 1252 void mark_evac_failure_object(const oop obj, uint worker_id) const; 1253 1254 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1255 1256 // Refinement 1257 1258 G1ConcurrentRefine* concurrent_refine() const { return _cr; } 1259 1260 // Optimized nmethod scanning support routines 1261 1262 // Register the given nmethod with the G1 heap. 1263 void register_nmethod(nmethod* nm) override; 1264 1265 // Unregister the given nmethod from the G1 heap. 1266 void unregister_nmethod(nmethod* nm) override; 1267 1268 // No nmethod flushing needed. 1269 void flush_nmethod(nmethod* nm) override {} 1270 1271 // No nmethod verification implemented. 1272 void verify_nmethod(nmethod* nm) override {} 1273 1274 // Recalculate amount of used memory after GC. Must be called after all allocation 1275 // has finished. 1276 void update_used_after_gc(bool evacuation_failed); 1277 // Reset and re-enable the hot card cache. 1278 // Note the counts for the cards in the regions in the 1279 // collection set are reset when the collection set is freed. 1280 void reset_hot_card_cache(); 1281 // Free up superfluous code root memory. 1282 void purge_code_root_memory(); 1283 1284 // Rebuild the code root lists for each region 1285 // after a full GC. 1286 void rebuild_code_roots(); 1287 1288 // Performs cleaning of data structures after class unloading. 1289 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); 1290 1291 // Verification 1292 1293 // Perform any cleanup actions necessary before allowing a verification. 1294 void prepare_for_verify() override; 1295 1296 // Perform verification. 1297 1298 // vo == UsePrevMarking -> use "prev" marking information, 1299 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS 1300 // 1301 // NOTE: Only the "prev" marking information is guaranteed to be 1302 // consistent most of the time, so most calls to this should use 1303 // vo == UsePrevMarking. 1304 // Currently there is only one place where this is called with 1305 // vo == UseFullMarking, which is to verify the marking during a 1306 // full GC. 1307 void verify(VerifyOption vo) override; 1308 1309 // WhiteBox testing support. 1310 bool supports_concurrent_gc_breakpoints() const override; 1311 1312 WorkerThreads* safepoint_workers() override { return _workers; } 1313 1314 bool is_archived_object(oop object) const override; 1315 1316 // The methods below are here for convenience and dispatch the 1317 // appropriate method depending on value of the given VerifyOption 1318 // parameter. The values for that parameter, and their meanings, 1319 // are the same as those above. 1320 1321 bool is_obj_dead_cond(const oop obj, 1322 const HeapRegion* hr, 1323 const VerifyOption vo) const; 1324 1325 bool is_obj_dead_cond(const oop obj, 1326 const VerifyOption vo) const; 1327 1328 G1HeapSummary create_g1_heap_summary(); 1329 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1330 1331 // Printing 1332 private: 1333 void print_heap_regions() const; 1334 void print_regions_on(outputStream* st) const; 1335 1336 public: 1337 void print_on(outputStream* st) const override; 1338 void print_extended_on(outputStream* st) const override; 1339 void print_on_error(outputStream* st) const override; 1340 1341 void gc_threads_do(ThreadClosure* tc) const override; 1342 1343 // Override 1344 void print_tracing_info() const override; 1345 1346 // The following two methods are helpful for debugging RSet issues. 1347 void print_cset_rsets() PRODUCT_RETURN; 1348 void print_all_rsets() PRODUCT_RETURN; 1349 1350 // Used to print information about locations in the hs_err file. 1351 bool print_location(outputStream* st, void* addr) const override; 1352 }; 1353 1354 // Scoped object that performs common pre- and post-gc heap printing operations. 1355 class G1HeapPrinterMark : public StackObj { 1356 G1CollectedHeap* _g1h; 1357 G1HeapTransition _heap_transition; 1358 1359 public: 1360 G1HeapPrinterMark(G1CollectedHeap* g1h); 1361 ~G1HeapPrinterMark(); 1362 }; 1363 1364 // Scoped object that performs common pre- and post-gc operations related to 1365 // JFR events. 1366 class G1JFRTracerMark : public StackObj { 1367 protected: 1368 STWGCTimer* _timer; 1369 GCTracer* _tracer; 1370 1371 public: 1372 G1JFRTracerMark(STWGCTimer* timer, GCTracer* tracer); 1373 ~G1JFRTracerMark(); 1374 }; 1375 1376 #endif // SHARE_GC_G1_G1COLLECTEDHEAP_HPP