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 SlidingForwarding; 88 class WorkerThreads; 89 90 typedef OverflowTaskQueue<ScannerTask, mtGC> G1ScannerTasksQueue; 91 typedef GenericTaskQueueSet<G1ScannerTasksQueue, mtGC> G1ScannerTasksQueueSet; 92 93 typedef int RegionIdx_t; // needs to hold [ 0..max_reserved_regions() ) 94 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 95 96 // The G1 STW is alive closure. 97 // An instance is embedded into the G1CH and used as the 98 // (optional) _is_alive_non_header closure in the STW 99 // reference processor. It is also extensively used during 100 // reference processing during STW evacuation pauses. 101 class G1STWIsAliveClosure : public BoolObjectClosure { 102 G1CollectedHeap* _g1h; 103 public: 104 G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {} 105 bool do_object_b(oop p) override; 106 }; 107 108 class G1STWSubjectToDiscoveryClosure : public BoolObjectClosure { 109 G1CollectedHeap* _g1h; 110 public: 111 G1STWSubjectToDiscoveryClosure(G1CollectedHeap* g1h) : _g1h(g1h) {} 112 bool do_object_b(oop p) override; 113 }; 114 115 class G1RegionMappingChangedListener : public G1MappingChangedListener { 116 private: 117 void reset_from_card_cache(uint start_idx, size_t num_regions); 118 public: 119 void on_commit(uint start_idx, size_t num_regions, bool zero_filled) override; 120 }; 121 122 class G1CollectedHeap : public CollectedHeap { 123 friend class VM_G1CollectForAllocation; 124 friend class VM_G1CollectFull; 125 friend class VM_G1TryInitiateConcMark; 126 friend class VMStructs; 127 friend class MutatorAllocRegion; 128 friend class G1FullCollector; 129 friend class G1GCAllocRegion; 130 friend class G1HeapVerifier; 131 132 friend class G1YoungGCVerifierMark; 133 134 // Closures used in implementation. 135 friend class G1EvacuateRegionsTask; 136 friend class G1PLABAllocator; 137 138 // Other related classes. 139 friend class G1HeapPrinterMark; 140 friend class HeapRegionClaimer; 141 142 // Testing classes. 143 friend class G1CheckRegionAttrTableClosure; 144 145 private: 146 G1ServiceThread* _service_thread; 147 G1ServiceTask* _periodic_gc_task; 148 G1SegmentedArrayFreeMemoryTask* _free_segmented_array_memory_task; 149 150 WorkerThreads* _workers; 151 G1CardTable* _card_table; 152 153 Ticks _collection_pause_end; 154 155 SoftRefPolicy _soft_ref_policy; 156 157 static size_t _humongous_object_threshold_in_words; 158 159 // These sets keep track of old, archive and humongous regions respectively. 160 HeapRegionSet _old_set; 161 HeapRegionSet _archive_set; 162 HeapRegionSet _humongous_set; 163 164 // Young gen memory statistics before GC. 165 G1SegmentedArrayMemoryStats _young_gen_card_set_stats; 166 // Collection set candidates memory statistics after GC. 167 G1SegmentedArrayMemoryStats _collection_set_candidates_card_set_stats; 168 169 // The block offset table for the G1 heap. 170 G1BlockOffsetTable* _bot; 171 172 public: 173 void rebuild_free_region_list(); 174 // Start a new incremental collection set for the next pause. 175 void start_new_collection_set(); 176 177 void prepare_region_for_full_compaction(HeapRegion* hr); 178 179 private: 180 // Rebuilds the region sets / lists so that they are repopulated to 181 // reflect the contents of the heap. The only exception is the 182 // humongous set which was not torn down in the first place. If 183 // free_list_only is true, it will only rebuild the free list. 184 void rebuild_region_sets(bool free_list_only); 185 186 // Callback for region mapping changed events. 187 G1RegionMappingChangedListener _listener; 188 189 // Handle G1 NUMA support. 190 G1NUMA* _numa; 191 192 // The sequence of all heap regions in the heap. 193 HeapRegionManager _hrm; 194 195 // Manages all allocations with regions except humongous object allocations. 196 G1Allocator* _allocator; 197 198 G1YoungGCEvacFailureInjector _evac_failure_injector; 199 200 // Manages all heap verification. 201 G1HeapVerifier* _verifier; 202 203 // Outside of GC pauses, the number of bytes used in all regions other 204 // than the current allocation region(s). 205 volatile size_t _summary_bytes_used; 206 207 void increase_used(size_t bytes); 208 void decrease_used(size_t bytes); 209 210 void set_used(size_t bytes); 211 212 // Number of bytes used in all regions during GC. Typically changed when 213 // retiring a GC alloc region. 214 size_t _bytes_used_during_gc; 215 216 public: 217 size_t bytes_used_during_gc() const { return _bytes_used_during_gc; } 218 219 private: 220 // Class that handles archive allocation ranges. 221 G1ArchiveAllocator* _archive_allocator; 222 223 // GC allocation statistics policy for survivors. 224 G1EvacStats _survivor_evac_stats; 225 226 // GC allocation statistics policy for tenured objects. 227 G1EvacStats _old_evac_stats; 228 229 // Helper for monitoring and management support. 230 G1MonitoringSupport* _monitoring_support; 231 232 SlidingForwarding* _forwarding; 233 234 // Records whether the region at the given index is (still) a 235 // candidate for eager reclaim. Only valid for humongous start 236 // regions; other regions have unspecified values. Humongous start 237 // regions are initialized at start of collection pause, with 238 // candidates removed from the set as they are found reachable from 239 // roots or the young generation. 240 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 241 protected: 242 bool default_value() const override { return false; } 243 public: 244 void clear() { G1BiasedMappedArray<bool>::clear(); } 245 void set_candidate(uint region, bool value) { 246 set_by_index(region, value); 247 } 248 bool is_candidate(uint region) { 249 return get_by_index(region); 250 } 251 }; 252 253 HumongousReclaimCandidates _humongous_reclaim_candidates; 254 uint _num_humongous_objects; // Current amount of (all) humongous objects found in the heap. 255 uint _num_humongous_reclaim_candidates; // Number of humongous object eager reclaim candidates. 256 public: 257 uint num_humongous_objects() const { return _num_humongous_objects; } 258 uint num_humongous_reclaim_candidates() const { return _num_humongous_reclaim_candidates; } 259 bool has_humongous_reclaim_candidates() const { return _num_humongous_reclaim_candidates > 0; } 260 261 bool should_do_eager_reclaim() const; 262 263 void set_humongous_stats(uint num_humongous_total, uint num_humongous_candidates); 264 265 bool should_sample_collection_set_candidates() const; 266 void set_collection_set_candidates_stats(G1SegmentedArrayMemoryStats& stats); 267 void set_young_gen_card_set_stats(const G1SegmentedArrayMemoryStats& stats); 268 269 SlidingForwarding* forwarding() const { 270 return _forwarding; 271 } 272 273 private: 274 275 G1HRPrinter _hr_printer; 276 277 // Return true if an explicit GC should start a concurrent cycle instead 278 // of doing a STW full GC. A concurrent cycle should be started if: 279 // (a) cause == _g1_humongous_allocation, 280 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent, 281 // (c) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent, 282 // (d) cause == _wb_conc_mark or _wb_breakpoint, 283 // (e) cause == _g1_periodic_collection and +G1PeriodicGCInvokesConcurrent. 284 bool should_do_concurrent_full_gc(GCCause::Cause cause); 285 286 // Attempt to start a concurrent cycle with the indicated cause. 287 // precondition: should_do_concurrent_full_gc(cause) 288 bool try_collect_concurrently(GCCause::Cause cause, 289 uint gc_counter, 290 uint old_marking_started_before); 291 292 // indicates whether we are in young or mixed GC mode 293 G1CollectorState _collector_state; 294 295 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 296 // concurrent cycles) we have started. 297 volatile uint _old_marking_cycles_started; 298 299 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 300 // concurrent cycles) we have completed. 301 volatile uint _old_marking_cycles_completed; 302 303 // This is a non-product method that is helpful for testing. It is 304 // called at the end of a GC and artificially expands the heap by 305 // allocating a number of dead regions. This way we can induce very 306 // frequent marking cycles and stress the cleanup / concurrent 307 // cleanup code more (as all the regions that will be allocated by 308 // this method will be found dead by the marking cycle). 309 void allocate_dummy_regions() PRODUCT_RETURN; 310 311 // Create a memory mapper for auxiliary data structures of the given size and 312 // translation factor. 313 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 314 size_t size, 315 size_t translation_factor); 316 317 void trace_heap(GCWhen::Type when, const GCTracer* tracer) override; 318 319 // These are macros so that, if the assert fires, we get the correct 320 // line number, file, etc. 321 322 #define heap_locking_asserts_params(_extra_message_) \ 323 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 324 (_extra_message_), \ 325 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 326 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 327 BOOL_TO_STR(Thread::current()->is_VM_thread()) 328 329 #define assert_heap_locked() \ 330 do { \ 331 assert(Heap_lock->owned_by_self(), \ 332 heap_locking_asserts_params("should be holding the Heap_lock")); \ 333 } while (0) 334 335 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 336 do { \ 337 assert(Heap_lock->owned_by_self() || \ 338 (SafepointSynchronize::is_at_safepoint() && \ 339 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 340 heap_locking_asserts_params("should be holding the Heap_lock or " \ 341 "should be at a safepoint")); \ 342 } while (0) 343 344 #define assert_heap_locked_and_not_at_safepoint() \ 345 do { \ 346 assert(Heap_lock->owned_by_self() && \ 347 !SafepointSynchronize::is_at_safepoint(), \ 348 heap_locking_asserts_params("should be holding the Heap_lock and " \ 349 "should not be at a safepoint")); \ 350 } while (0) 351 352 #define assert_heap_not_locked() \ 353 do { \ 354 assert(!Heap_lock->owned_by_self(), \ 355 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 356 } while (0) 357 358 #define assert_heap_not_locked_and_not_at_safepoint() \ 359 do { \ 360 assert(!Heap_lock->owned_by_self() && \ 361 !SafepointSynchronize::is_at_safepoint(), \ 362 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 363 "should not be at a safepoint")); \ 364 } while (0) 365 366 #define assert_at_safepoint_on_vm_thread() \ 367 do { \ 368 assert_at_safepoint(); \ 369 assert(Thread::current_or_null() != NULL, "no current thread"); \ 370 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \ 371 } while (0) 372 373 #ifdef ASSERT 374 #define assert_used_and_recalculate_used_equal(g1h) \ 375 do { \ 376 size_t cur_used_bytes = g1h->used(); \ 377 size_t recal_used_bytes = g1h->recalculate_used(); \ 378 assert(cur_used_bytes == recal_used_bytes, "Used(" SIZE_FORMAT ") is not" \ 379 " same as recalculated used(" SIZE_FORMAT ").", \ 380 cur_used_bytes, recal_used_bytes); \ 381 } while (0) 382 #else 383 #define assert_used_and_recalculate_used_equal(g1h) do {} while(0) 384 #endif 385 386 // The young region list. 387 G1EdenRegions _eden; 388 G1SurvivorRegions _survivor; 389 390 STWGCTimer* _gc_timer_stw; 391 392 G1NewTracer* _gc_tracer_stw; 393 394 // The current policy object for the collector. 395 G1Policy* _policy; 396 G1HeapSizingPolicy* _heap_sizing_policy; 397 398 G1CollectionSet _collection_set; 399 400 // Try to allocate a single non-humongous HeapRegion sufficient for 401 // an allocation of the given word_size. If do_expand is true, 402 // attempt to expand the heap if necessary to satisfy the allocation 403 // request. 'type' takes the type of region to be allocated. (Use constants 404 // Old, Eden, Humongous, Survivor defined in HeapRegionType.) 405 HeapRegion* new_region(size_t word_size, 406 HeapRegionType type, 407 bool do_expand, 408 uint node_index = G1NUMA::AnyNodeIndex); 409 410 // Initialize a contiguous set of free regions of length num_regions 411 // and starting at index first so that they appear as a single 412 // humongous region. 413 HeapWord* humongous_obj_allocate_initialize_regions(HeapRegion* first_hr, 414 uint num_regions, 415 size_t word_size); 416 417 // Attempt to allocate a humongous object of the given size. Return 418 // NULL if unsuccessful. 419 HeapWord* humongous_obj_allocate(size_t word_size); 420 421 // The following two methods, allocate_new_tlab() and 422 // mem_allocate(), are the two main entry points from the runtime 423 // into the G1's allocation routines. They have the following 424 // assumptions: 425 // 426 // * They should both be called outside safepoints. 427 // 428 // * They should both be called without holding the Heap_lock. 429 // 430 // * All allocation requests for new TLABs should go to 431 // allocate_new_tlab(). 432 // 433 // * All non-TLAB allocation requests should go to mem_allocate(). 434 // 435 // * If either call cannot satisfy the allocation request using the 436 // current allocating region, they will try to get a new one. If 437 // this fails, they will attempt to do an evacuation pause and 438 // retry the allocation. 439 // 440 // * If all allocation attempts fail, even after trying to schedule 441 // an evacuation pause, allocate_new_tlab() will return NULL, 442 // whereas mem_allocate() will attempt a heap expansion and/or 443 // schedule a Full GC. 444 // 445 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 446 // should never be called with word_size being humongous. All 447 // humongous allocation requests should go to mem_allocate() which 448 // will satisfy them with a special path. 449 450 HeapWord* allocate_new_tlab(size_t min_size, 451 size_t requested_size, 452 size_t* actual_size) override; 453 454 HeapWord* mem_allocate(size_t word_size, 455 bool* gc_overhead_limit_was_exceeded) override; 456 457 // First-level mutator allocation attempt: try to allocate out of 458 // the mutator alloc region without taking the Heap_lock. This 459 // should only be used for non-humongous allocations. 460 inline HeapWord* attempt_allocation(size_t min_word_size, 461 size_t desired_word_size, 462 size_t* actual_word_size); 463 464 // Second-level mutator allocation attempt: take the Heap_lock and 465 // retry the allocation attempt, potentially scheduling a GC 466 // pause. This should only be used for non-humongous allocations. 467 HeapWord* attempt_allocation_slow(size_t word_size); 468 469 // Takes the Heap_lock and attempts a humongous allocation. It can 470 // potentially schedule a GC pause. 471 HeapWord* attempt_allocation_humongous(size_t word_size); 472 473 // Allocation attempt that should be called during safepoints (e.g., 474 // at the end of a successful GC). expect_null_mutator_alloc_region 475 // specifies whether the mutator alloc region is expected to be NULL 476 // or not. 477 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 478 bool expect_null_mutator_alloc_region); 479 480 // These methods are the "callbacks" from the G1AllocRegion class. 481 482 // For mutator alloc regions. 483 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force, uint node_index); 484 void retire_mutator_alloc_region(HeapRegion* alloc_region, 485 size_t allocated_bytes); 486 487 // For GC alloc regions. 488 bool has_more_regions(G1HeapRegionAttr dest); 489 HeapRegion* new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index); 490 void retire_gc_alloc_region(HeapRegion* alloc_region, 491 size_t allocated_bytes, G1HeapRegionAttr dest); 492 493 // - if explicit_gc is true, the GC is for a System.gc() etc, 494 // otherwise it's for a failed allocation. 495 // - if clear_all_soft_refs is true, all soft references should be 496 // cleared during the GC. 497 // - if do_maximal_compaction is true, full gc will do a maximally 498 // compacting collection, leaving no dead wood. 499 // - it returns false if it is unable to do the collection due to the 500 // GC locker being active, true otherwise. 501 bool do_full_collection(bool explicit_gc, 502 bool clear_all_soft_refs, 503 bool do_maximal_compaction); 504 505 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 506 void do_full_collection(bool clear_all_soft_refs) override; 507 508 // Helper to do a full collection that clears soft references. 509 bool upgrade_to_full_collection(); 510 511 // Callback from VM_G1CollectForAllocation operation. 512 // This function does everything necessary/possible to satisfy a 513 // failed allocation request (including collection, expansion, etc.) 514 HeapWord* satisfy_failed_allocation(size_t word_size, 515 bool* succeeded); 516 // Internal helpers used during full GC to split it up to 517 // increase readability. 518 void abort_concurrent_cycle(); 519 void verify_before_full_collection(bool explicit_gc); 520 void prepare_heap_for_full_collection(); 521 void prepare_heap_for_mutators(); 522 void abort_refinement(); 523 void verify_after_full_collection(); 524 void print_heap_after_full_collection(); 525 526 // Helper method for satisfy_failed_allocation() 527 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 528 bool do_gc, 529 bool maximal_compaction, 530 bool expect_null_mutator_alloc_region, 531 bool* gc_succeeded); 532 533 // Attempting to expand the heap sufficiently 534 // to support an allocation of the given "word_size". If 535 // successful, perform the allocation and return the address of the 536 // allocated block, or else "NULL". 537 HeapWord* expand_and_allocate(size_t word_size); 538 539 void verify_numa_regions(const char* desc); 540 541 public: 542 // If during a concurrent start pause we may install a pending list head which is not 543 // otherwise reachable, ensure that it is marked in the bitmap for concurrent marking 544 // to discover. 545 void make_pending_list_reachable(); 546 547 G1ServiceThread* service_thread() const { return _service_thread; } 548 549 WorkerThreads* workers() const { return _workers; } 550 551 // Run the given batch task using the workers. 552 void run_batch_task(G1BatchedTask* cl); 553 554 G1Allocator* allocator() { 555 return _allocator; 556 } 557 558 G1YoungGCEvacFailureInjector* evac_failure_injector() { return &_evac_failure_injector; } 559 560 G1HeapVerifier* verifier() { 561 return _verifier; 562 } 563 564 G1MonitoringSupport* monitoring_support() { 565 assert(_monitoring_support != nullptr, "should have been initialized"); 566 return _monitoring_support; 567 } 568 569 void resize_heap_if_necessary(); 570 571 // Check if there is memory to uncommit and if so schedule a task to do it. 572 void uncommit_regions_if_necessary(); 573 // Immediately uncommit uncommittable regions. 574 uint uncommit_regions(uint region_limit); 575 bool has_uncommittable_regions(); 576 577 G1NUMA* numa() const { return _numa; } 578 579 // Expand the garbage-first heap by at least the given size (in bytes!). 580 // Returns true if the heap was expanded by the requested amount; 581 // false otherwise. 582 // (Rounds up to a HeapRegion boundary.) 583 bool expand(size_t expand_bytes, WorkerThreads* pretouch_workers = NULL, double* expand_time_ms = NULL); 584 bool expand_single_region(uint node_index); 585 586 // Returns the PLAB statistics for a given destination. 587 inline G1EvacStats* alloc_buffer_stats(G1HeapRegionAttr dest); 588 589 // Determines PLAB size for a given destination. 590 inline size_t desired_plab_sz(G1HeapRegionAttr dest); 591 592 // Do anything common to GC's. 593 void gc_prologue(bool full); 594 void gc_epilogue(bool full); 595 596 // Does the given region fulfill remembered set based eager reclaim candidate requirements? 597 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const; 598 599 // Modify the reclaim candidate set and test for presence. 600 // These are only valid for starts_humongous regions. 601 inline void set_humongous_reclaim_candidate(uint region, bool value); 602 inline bool is_humongous_reclaim_candidate(uint region); 603 604 // Remove from the reclaim candidate set. Also remove from the 605 // collection set so that later encounters avoid the slow path. 606 inline void set_humongous_is_live(oop obj); 607 608 // Register the given region to be part of the collection set. 609 inline void register_humongous_region_with_region_attr(uint index); 610 611 // We register a region with the fast "in collection set" test. We 612 // simply set to true the array slot corresponding to this region. 613 void register_young_region_with_region_attr(HeapRegion* r) { 614 _region_attr.set_in_young(r->hrm_index()); 615 } 616 inline void register_new_survivor_region_with_region_attr(HeapRegion* r); 617 inline void register_region_with_region_attr(HeapRegion* r); 618 inline void register_old_region_with_region_attr(HeapRegion* r); 619 inline void register_optional_region_with_region_attr(HeapRegion* r); 620 621 void clear_region_attr(const HeapRegion* hr) { 622 _region_attr.clear(hr); 623 } 624 625 void clear_region_attr() { 626 _region_attr.clear(); 627 } 628 629 // Verify that the G1RegionAttr remset tracking corresponds to actual remset tracking 630 // for all regions. 631 void verify_region_attr_remset_is_tracked() PRODUCT_RETURN; 632 633 void clear_prev_bitmap_for_region(HeapRegion* hr); 634 635 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 636 637 // This is called at the start of either a concurrent cycle or a Full 638 // GC to update the number of old marking cycles started. 639 void increment_old_marking_cycles_started(); 640 641 // This is called at the end of either a concurrent cycle or a Full 642 // GC to update the number of old marking cycles completed. Those two 643 // can happen in a nested fashion, i.e., we start a concurrent 644 // cycle, a Full GC happens half-way through it which ends first, 645 // and then the cycle notices that a Full GC happened and ends 646 // too. The concurrent parameter is a boolean to help us do a bit 647 // tighter consistency checking in the method. If concurrent is 648 // false, the caller is the inner caller in the nesting (i.e., the 649 // Full GC). If concurrent is true, the caller is the outer caller 650 // in this nesting (i.e., the concurrent cycle). Further nesting is 651 // not currently supported. The end of this call also notifies 652 // the G1OldGCCount_lock in case a Java thread is waiting for a full 653 // GC to happen (e.g., it called System.gc() with 654 // +ExplicitGCInvokesConcurrent). 655 // whole_heap_examined should indicate that during that old marking 656 // cycle the whole heap has been examined for live objects (as opposed 657 // to only parts, or aborted before completion). 658 void increment_old_marking_cycles_completed(bool concurrent, bool whole_heap_examined); 659 660 uint old_marking_cycles_started() const { 661 return _old_marking_cycles_started; 662 } 663 664 uint old_marking_cycles_completed() const { 665 return _old_marking_cycles_completed; 666 } 667 668 G1HRPrinter* hr_printer() { return &_hr_printer; } 669 670 // Allocates a new heap region instance. 671 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 672 673 // Allocate the highest free region in the reserved heap. This will commit 674 // regions as necessary. 675 HeapRegion* alloc_highest_free_region(); 676 677 // Frees a region by resetting its metadata and adding it to the free list 678 // passed as a parameter (this is usually a local list which will be appended 679 // to the master free list later or NULL if free list management is handled 680 // in another way). 681 // Callers must ensure they are the only one calling free on the given region 682 // at the same time. 683 void free_region(HeapRegion* hr, FreeRegionList* free_list); 684 685 // It dirties the cards that cover the block so that the post 686 // write barrier never queues anything when updating objects on this 687 // block. It is assumed (and in fact we assert) that the block 688 // belongs to a young region. 689 inline void dirty_young_block(HeapWord* start, size_t word_size); 690 691 // Frees a humongous region by collapsing it into individual regions 692 // and calling free_region() for each of them. The freed regions 693 // will be added to the free list that's passed as a parameter (this 694 // is usually a local list which will be appended to the master free 695 // list later). 696 // The method assumes that only a single thread is ever calling 697 // this for a particular region at once. 698 void free_humongous_region(HeapRegion* hr, 699 FreeRegionList* free_list); 700 701 // Facility for allocating in 'archive' regions in high heap memory and 702 // recording the allocated ranges. These should all be called from the 703 // VM thread at safepoints, without the heap lock held. They can be used 704 // to create and archive a set of heap regions which can be mapped at the 705 // same fixed addresses in a subsequent JVM invocation. 706 void begin_archive_alloc_range(bool open = false); 707 708 // Check if the requested size would be too large for an archive allocation. 709 bool is_archive_alloc_too_large(size_t word_size); 710 711 // Allocate memory of the requested size from the archive region. This will 712 // return NULL if the size is too large or if no memory is available. It 713 // does not trigger a garbage collection. 714 HeapWord* archive_mem_allocate(size_t word_size); 715 716 // Optionally aligns the end address and returns the allocated ranges in 717 // an array of MemRegions in order of ascending addresses. 718 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 719 size_t end_alignment_in_bytes = 0); 720 721 // Facility for allocating a fixed range within the heap and marking 722 // the containing regions as 'archive'. For use at JVM init time, when the 723 // caller may mmap archived heap data at the specified range(s). 724 // Verify that the MemRegions specified in the argument array are within the 725 // reserved heap. 726 bool check_archive_addresses(MemRegion* range, size_t count); 727 728 // Commit the appropriate G1 regions containing the specified MemRegions 729 // and mark them as 'archive' regions. The regions in the array must be 730 // non-overlapping and in order of ascending address. 731 bool alloc_archive_regions(MemRegion* range, size_t count, bool open); 732 733 // Insert any required filler objects in the G1 regions around the specified 734 // ranges to make the regions parseable. This must be called after 735 // alloc_archive_regions, and after class loading has occurred. 736 void fill_archive_regions(MemRegion* range, size_t count); 737 738 // Populate the G1BlockOffsetTablePart for archived regions with the given 739 // memory ranges. 740 void populate_archive_regions_bot_part(MemRegion* range, size_t count); 741 742 // For each of the specified MemRegions, uncommit the containing G1 regions 743 // which had been allocated by alloc_archive_regions. This should be called 744 // rather than fill_archive_regions at JVM init time if the archive file 745 // mapping failed, with the same non-overlapping and sorted MemRegion array. 746 void dealloc_archive_regions(MemRegion* range, size_t count); 747 748 private: 749 750 // Shrink the garbage-first heap by at most the given size (in bytes!). 751 // (Rounds down to a HeapRegion boundary.) 752 void shrink(size_t shrink_bytes); 753 void shrink_helper(size_t expand_bytes); 754 755 // Schedule the VM operation that will do an evacuation pause to 756 // satisfy an allocation request of word_size. *succeeded will 757 // return whether the VM operation was successful (it did do an 758 // evacuation pause) or not (another thread beat us to it or the GC 759 // locker was active). Given that we should not be holding the 760 // Heap_lock when we enter this method, we will pass the 761 // gc_count_before (i.e., total_collections()) as a parameter since 762 // it has to be read while holding the Heap_lock. Currently, both 763 // methods that call do_collection_pause() release the Heap_lock 764 // before the call, so it's easy to read gc_count_before just before. 765 HeapWord* do_collection_pause(size_t word_size, 766 uint gc_count_before, 767 bool* succeeded, 768 GCCause::Cause gc_cause); 769 770 // Perform an incremental collection at a safepoint, possibly 771 // followed by a by-policy upgrade to a full collection. Returns 772 // false if unable to do the collection due to the GC locker being 773 // active, true otherwise. 774 // precondition: at safepoint on VM thread 775 // precondition: !is_gc_active() 776 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 777 778 // Helper for do_collection_pause_at_safepoint, containing the guts 779 // of the incremental collection pause, executed by the vm thread. 780 void do_collection_pause_at_safepoint_helper(double target_pause_time_ms); 781 782 G1HeapVerifier::G1VerifyType young_collection_verify_type() const; 783 void verify_before_young_collection(G1HeapVerifier::G1VerifyType type); 784 void verify_after_young_collection(G1HeapVerifier::G1VerifyType type); 785 786 public: 787 // Start a concurrent cycle. 788 void start_concurrent_cycle(bool concurrent_operation_is_full_mark); 789 790 void prepare_tlabs_for_mutator(); 791 792 void retire_tlabs(); 793 794 void expand_heap_after_young_collection(); 795 // Update object copying statistics. 796 void record_obj_copy_mem_stats(); 797 798 private: 799 // The hot card cache for remembered set insertion optimization. 800 G1HotCardCache* _hot_card_cache; 801 802 // The g1 remembered set of the heap. 803 G1RemSet* _rem_set; 804 // Global card set configuration 805 G1CardSetConfiguration _card_set_config; 806 807 public: 808 // After a collection pause, reset eden and the collection set. 809 void clear_eden(); 810 void clear_collection_set(); 811 812 // Abandon the current collection set without recording policy 813 // statistics or updating free lists. 814 void abandon_collection_set(G1CollectionSet* collection_set); 815 816 // The concurrent marker (and the thread it runs in.) 817 G1ConcurrentMark* _cm; 818 G1ConcurrentMarkThread* _cm_thread; 819 820 // The concurrent refiner. 821 G1ConcurrentRefine* _cr; 822 823 // The parallel task queues 824 G1ScannerTasksQueueSet *_task_queues; 825 826 // ("Weak") Reference processing support. 827 // 828 // G1 has 2 instances of the reference processor class. 829 // 830 // One (_ref_processor_cm) handles reference object discovery and subsequent 831 // processing during concurrent marking cycles. Discovery is enabled/disabled 832 // at the start/end of a concurrent marking cycle. 833 // 834 // The other (_ref_processor_stw) handles reference object discovery and 835 // processing during incremental evacuation pauses and full GC pauses. 836 // 837 // ## Incremental evacuation pauses 838 // 839 // STW ref processor discovery is enabled/disabled at the start/end of an 840 // incremental evacuation pause. No particular handling of the CM ref 841 // processor is needed, apart from treating the discovered references as 842 // roots; CM discovery does not need to be temporarily disabled as all 843 // marking threads are paused during incremental evacuation pauses. 844 // 845 // ## Full GC pauses 846 // 847 // We abort any ongoing concurrent marking cycle, disable CM discovery, and 848 // temporarily substitute a new closure for the STW ref processor's 849 // _is_alive_non_header field (old value is restored after the full GC). Then 850 // STW ref processor discovery is enabled, and marking & compaction 851 // commences. 852 853 // The (stw) reference processor... 854 ReferenceProcessor* _ref_processor_stw; 855 856 // During reference object discovery, the _is_alive_non_header 857 // closure (if non-null) is applied to the referent object to 858 // determine whether the referent is live. If so then the 859 // reference object does not need to be 'discovered' and can 860 // be treated as a regular oop. This has the benefit of reducing 861 // the number of 'discovered' reference objects that need to 862 // be processed. 863 // 864 // Instance of the is_alive closure for embedding into the 865 // STW reference processor as the _is_alive_non_header field. 866 // Supplying a value for the _is_alive_non_header field is 867 // optional but doing so prevents unnecessary additions to 868 // the discovered lists during reference discovery. 869 G1STWIsAliveClosure _is_alive_closure_stw; 870 871 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw; 872 873 // The (concurrent marking) reference processor... 874 ReferenceProcessor* _ref_processor_cm; 875 876 // Instance of the concurrent mark is_alive closure for embedding 877 // into the Concurrent Marking reference processor as the 878 // _is_alive_non_header field. Supplying a value for the 879 // _is_alive_non_header field is optional but doing so prevents 880 // unnecessary additions to the discovered lists during reference 881 // discovery. 882 G1CMIsAliveClosure _is_alive_closure_cm; 883 884 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm; 885 public: 886 887 G1ScannerTasksQueueSet* task_queues() const; 888 G1ScannerTasksQueue* task_queue(uint i) const; 889 890 // Create a G1CollectedHeap. 891 // Must call the initialize method afterwards. 892 // May not return if something goes wrong. 893 G1CollectedHeap(); 894 895 private: 896 jint initialize_concurrent_refinement(); 897 jint initialize_service_thread(); 898 public: 899 // Initialize the G1CollectedHeap to have the initial and 900 // maximum sizes and remembered and barrier sets 901 // specified by the policy object. 902 jint initialize() override; 903 904 // Returns whether concurrent mark threads (and the VM) are about to terminate. 905 bool concurrent_mark_is_terminating() const; 906 907 void stop() override; 908 void safepoint_synchronize_begin() override; 909 void safepoint_synchronize_end() override; 910 911 // Does operations required after initialization has been done. 912 void post_initialize() override; 913 914 // Initialize weak reference processing. 915 void ref_processing_init(); 916 917 Name kind() const override { 918 return CollectedHeap::G1; 919 } 920 921 const char* name() const override { 922 return "G1"; 923 } 924 925 const G1CollectorState* collector_state() const { return &_collector_state; } 926 G1CollectorState* collector_state() { return &_collector_state; } 927 928 // The current policy object for the collector. 929 G1Policy* policy() const { return _policy; } 930 // The remembered set. 931 G1RemSet* rem_set() const { return _rem_set; } 932 933 inline G1GCPhaseTimes* phase_times() const; 934 935 const G1CollectionSet* collection_set() const { return &_collection_set; } 936 G1CollectionSet* collection_set() { return &_collection_set; } 937 938 SoftRefPolicy* soft_ref_policy() override; 939 940 void initialize_serviceability() override; 941 MemoryUsage memory_usage() override; 942 GrowableArray<GCMemoryManager*> memory_managers() override; 943 GrowableArray<MemoryPool*> memory_pools() override; 944 945 void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) override; 946 947 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 948 void iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id); 949 950 // The shared block offset table array. 951 G1BlockOffsetTable* bot() const { return _bot; } 952 953 // Reference Processing accessors 954 955 // The STW reference processor.... 956 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 957 958 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 959 STWGCTimer* gc_timer_stw() const { return _gc_timer_stw; } 960 961 // The Concurrent Marking reference processor... 962 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 963 964 size_t unused_committed_regions_in_bytes() const; 965 966 size_t capacity() const override; 967 size_t used() const override; 968 // This should be called when we're not holding the heap lock. The 969 // result might be a bit inaccurate. 970 size_t used_unlocked() const; 971 size_t recalculate_used() const; 972 973 // These virtual functions do the actual allocation. 974 // Some heaps may offer a contiguous region for shared non-blocking 975 // allocation, via inlined code (by exporting the address of the top and 976 // end fields defining the extent of the contiguous allocation region.) 977 // But G1CollectedHeap doesn't yet support this. 978 979 bool is_maximal_no_gc() const override { 980 return _hrm.available() == 0; 981 } 982 983 // Returns true if an incremental GC should be upgrade to a full gc. This 984 // is done when there are no free regions and the heap can't be expanded. 985 bool should_upgrade_to_full_gc() const { 986 return is_maximal_no_gc() && num_free_regions() == 0; 987 } 988 989 // The current number of regions in the heap. 990 uint num_regions() const { return _hrm.length(); } 991 992 // The max number of regions reserved for the heap. Except for static array 993 // sizing purposes you probably want to use max_regions(). 994 uint max_reserved_regions() const { return _hrm.reserved_length(); } 995 996 // Max number of regions that can be committed. 997 uint max_regions() const { return _hrm.max_length(); } 998 999 // The number of regions that are completely free. 1000 uint num_free_regions() const { return _hrm.num_free_regions(); } 1001 1002 // The number of regions that can be allocated into. 1003 uint num_free_or_available_regions() const { return num_free_regions() + _hrm.available(); } 1004 1005 MemoryUsage get_auxiliary_data_memory_usage() const { 1006 return _hrm.get_auxiliary_data_memory_usage(); 1007 } 1008 1009 // The number of regions that are not completely free. 1010 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1011 1012 #ifdef ASSERT 1013 bool is_on_master_free_list(HeapRegion* hr) { 1014 return _hrm.is_free(hr); 1015 } 1016 #endif // ASSERT 1017 1018 inline void old_set_add(HeapRegion* hr); 1019 inline void old_set_remove(HeapRegion* hr); 1020 1021 inline void archive_set_add(HeapRegion* hr); 1022 1023 size_t non_young_capacity_bytes() { 1024 return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes; 1025 } 1026 1027 // Determine whether the given region is one that we are using as an 1028 // old GC alloc region. 1029 bool is_old_gc_alloc_region(HeapRegion* hr); 1030 1031 // Perform a collection of the heap; intended for use in implementing 1032 // "System.gc". This probably implies as full a collection as the 1033 // "CollectedHeap" supports. 1034 void collect(GCCause::Cause cause) override; 1035 1036 // Perform a collection of the heap with the given cause. 1037 // Returns whether this collection actually executed. 1038 bool try_collect(GCCause::Cause cause, const G1GCCounters& counters_before); 1039 1040 void start_concurrent_gc_for_metadata_allocation(GCCause::Cause gc_cause); 1041 1042 void remove_from_old_gen_sets(const uint old_regions_removed, 1043 const uint archive_regions_removed, 1044 const uint humongous_regions_removed); 1045 void prepend_to_freelist(FreeRegionList* list); 1046 void decrement_summary_bytes(size_t bytes); 1047 1048 bool is_in(const void* p) const override; 1049 1050 // Return "TRUE" iff the given object address is within the collection 1051 // set. Assumes that the reference points into the heap. 1052 inline bool is_in_cset(const HeapRegion *hr); 1053 inline bool is_in_cset(oop obj); 1054 inline bool is_in_cset(HeapWord* addr); 1055 1056 inline bool is_in_cset_or_humongous(const oop obj); 1057 1058 private: 1059 // This array is used for a quick test on whether a reference points into 1060 // the collection set or not. Each of the array's elements denotes whether the 1061 // corresponding region is in the collection set or not. 1062 G1HeapRegionAttrBiasedMappedArray _region_attr; 1063 1064 public: 1065 1066 inline G1HeapRegionAttr region_attr(const void* obj) const; 1067 inline G1HeapRegionAttr region_attr(uint idx) const; 1068 1069 MemRegion reserved() const { 1070 return _hrm.reserved(); 1071 } 1072 1073 bool is_in_reserved(const void* addr) const { 1074 return reserved().contains(addr); 1075 } 1076 1077 G1HotCardCache* hot_card_cache() const { return _hot_card_cache; } 1078 1079 G1CardTable* card_table() const { 1080 return _card_table; 1081 } 1082 1083 // Iteration functions. 1084 1085 void object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer); 1086 1087 // Iterate over all objects, calling "cl.do_object" on each. 1088 void object_iterate(ObjectClosure* cl) override; 1089 1090 ParallelObjectIteratorImpl* parallel_object_iterator(uint thread_num) override; 1091 1092 // Keep alive an object that was loaded with AS_NO_KEEPALIVE. 1093 void keep_alive(oop obj) override; 1094 1095 // Iterate over heap regions, in address order, terminating the 1096 // iteration early if the "do_heap_region" method returns "true". 1097 void heap_region_iterate(HeapRegionClosure* blk) const; 1098 1099 // Return the region with the given index. It assumes the index is valid. 1100 inline HeapRegion* region_at(uint index) const; 1101 inline HeapRegion* region_at_or_null(uint index) const; 1102 1103 // Return the next region (by index) that is part of the same 1104 // humongous object that hr is part of. 1105 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1106 1107 // Calculate the region index of the given address. Given address must be 1108 // within the heap. 1109 inline uint addr_to_region(HeapWord* addr) const; 1110 1111 inline HeapWord* bottom_addr_for_region(uint index) const; 1112 1113 // Two functions to iterate over the heap regions in parallel. Threads 1114 // compete using the HeapRegionClaimer to claim the regions before 1115 // applying the closure on them. 1116 // The _from_worker_offset version uses the HeapRegionClaimer and 1117 // the worker id to calculate a start offset to prevent all workers to 1118 // start from the point. 1119 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 1120 HeapRegionClaimer* hrclaimer, 1121 uint worker_id) const; 1122 1123 void heap_region_par_iterate_from_start(HeapRegionClosure* cl, 1124 HeapRegionClaimer* hrclaimer) const; 1125 1126 // Iterate over all regions in the collection set in parallel. 1127 void collection_set_par_iterate_all(HeapRegionClosure* cl, 1128 HeapRegionClaimer* hr_claimer, 1129 uint worker_id); 1130 1131 // Iterate over all regions currently in the current collection set. 1132 void collection_set_iterate_all(HeapRegionClosure* blk); 1133 1134 // Iterate over the regions in the current increment of the collection set. 1135 // Starts the iteration so that the start regions of a given worker id over the 1136 // set active_workers are evenly spread across the set of collection set regions 1137 // to be iterated. 1138 // The variant with the HeapRegionClaimer guarantees that the closure will be 1139 // applied to a particular region exactly once. 1140 void collection_set_iterate_increment_from(HeapRegionClosure *blk, uint worker_id) { 1141 collection_set_iterate_increment_from(blk, NULL, worker_id); 1142 } 1143 void collection_set_iterate_increment_from(HeapRegionClosure *blk, HeapRegionClaimer* hr_claimer, uint worker_id); 1144 // Iterate over the array of region indexes, uint regions[length], applying 1145 // the given HeapRegionClosure on each region. The worker_id will determine where 1146 // to start the iteration to allow for more efficient parallel iteration. 1147 void par_iterate_regions_array(HeapRegionClosure* cl, 1148 HeapRegionClaimer* hr_claimer, 1149 const uint regions[], 1150 size_t length, 1151 uint worker_id) const; 1152 1153 // Returns the HeapRegion that contains addr. addr must not be NULL. 1154 template <class T> 1155 inline HeapRegion* heap_region_containing(const T addr) const; 1156 1157 // Returns the HeapRegion that contains addr, or NULL if that is an uncommitted 1158 // region. addr must not be NULL. 1159 template <class T> 1160 inline HeapRegion* heap_region_containing_or_null(const T addr) const; 1161 1162 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1163 // each address in the (reserved) heap is a member of exactly 1164 // one block. The defining characteristic of a block is that it is 1165 // possible to find its size, and thus to progress forward to the next 1166 // block. (Blocks may be of different sizes.) Thus, blocks may 1167 // represent Java objects, or they might be free blocks in a 1168 // free-list-based heap (or subheap), as long as the two kinds are 1169 // distinguishable and the size of each is determinable. 1170 1171 // Returns the address of the start of the "block" that contains the 1172 // address "addr". We say "blocks" instead of "object" since some heaps 1173 // may not pack objects densely; a chunk may either be an object or a 1174 // non-object. 1175 HeapWord* block_start(const void* addr) const; 1176 1177 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1178 // the block is an object. 1179 bool block_is_obj(const HeapWord* addr) const; 1180 1181 // Section on thread-local allocation buffers (TLABs) 1182 // See CollectedHeap for semantics. 1183 1184 size_t tlab_capacity(Thread* ignored) const override; 1185 size_t tlab_used(Thread* ignored) const override; 1186 size_t max_tlab_size() const override; 1187 size_t unsafe_max_tlab_alloc(Thread* ignored) const override; 1188 1189 inline bool is_in_young(const oop obj) const; 1190 1191 // Returns "true" iff the given word_size is "very large". 1192 static bool is_humongous(size_t word_size) { 1193 // Note this has to be strictly greater-than as the TLABs 1194 // are capped at the humongous threshold and we want to 1195 // ensure that we don't try to allocate a TLAB as 1196 // humongous and that we don't allocate a humongous 1197 // object in a TLAB. 1198 return word_size > _humongous_object_threshold_in_words; 1199 } 1200 1201 // Returns the humongous threshold for a specific region size 1202 static size_t humongous_threshold_for(size_t region_size) { 1203 return (region_size / 2); 1204 } 1205 1206 // Returns the number of regions the humongous object of the given word size 1207 // requires. 1208 static size_t humongous_obj_size_in_regions(size_t word_size); 1209 1210 // Print the maximum heap capacity. 1211 size_t max_capacity() const override; 1212 1213 Tickspan time_since_last_collection() const { return Ticks::now() - _collection_pause_end; } 1214 1215 // Convenience function to be used in situations where the heap type can be 1216 // asserted to be this type. 1217 static G1CollectedHeap* heap() { 1218 return named_heap<G1CollectedHeap>(CollectedHeap::G1); 1219 } 1220 1221 void set_region_short_lived_locked(HeapRegion* hr); 1222 // add appropriate methods for any other surv rate groups 1223 1224 G1SurvivorRegions* survivor() { return &_survivor; } 1225 1226 uint eden_regions_count() const { return _eden.length(); } 1227 uint eden_regions_count(uint node_index) const { return _eden.regions_on_node(node_index); } 1228 uint survivor_regions_count() const { return _survivor.length(); } 1229 uint survivor_regions_count(uint node_index) const { return _survivor.regions_on_node(node_index); } 1230 size_t eden_regions_used_bytes() const { return _eden.used_bytes(); } 1231 size_t survivor_regions_used_bytes() const { return _survivor.used_bytes(); } 1232 uint young_regions_count() const { return _eden.length() + _survivor.length(); } 1233 uint old_regions_count() const { return _old_set.length(); } 1234 uint archive_regions_count() const { return _archive_set.length(); } 1235 uint humongous_regions_count() const { return _humongous_set.length(); } 1236 1237 #ifdef ASSERT 1238 bool check_young_list_empty(); 1239 #endif 1240 1241 bool is_marked_next(oop obj) const; 1242 1243 // Determine if an object is dead, given the object and also 1244 // the region to which the object belongs. 1245 inline bool is_obj_dead(const oop obj, const HeapRegion* hr) const; 1246 1247 // Determine if an object is dead, given only the object itself. 1248 // This will find the region to which the object belongs and 1249 // then call the region version of the same function. 1250 1251 // Added if it is NULL it isn't dead. 1252 1253 inline bool is_obj_dead(const oop obj) const; 1254 1255 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const; 1256 inline bool is_obj_dead_full(const oop obj) const; 1257 1258 // Mark the live object that failed evacuation in the prev bitmap. 1259 void mark_evac_failure_object(const oop obj, uint worker_id) const; 1260 1261 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1262 1263 // Refinement 1264 1265 G1ConcurrentRefine* concurrent_refine() const { return _cr; } 1266 1267 // Optimized nmethod scanning support routines 1268 1269 // Register the given nmethod with the G1 heap. 1270 void register_nmethod(nmethod* nm) override; 1271 1272 // Unregister the given nmethod from the G1 heap. 1273 void unregister_nmethod(nmethod* nm) override; 1274 1275 // No nmethod flushing needed. 1276 void flush_nmethod(nmethod* nm) override {} 1277 1278 // No nmethod verification implemented. 1279 void verify_nmethod(nmethod* nm) override {} 1280 1281 // Recalculate amount of used memory after GC. Must be called after all allocation 1282 // has finished. 1283 void update_used_after_gc(bool evacuation_failed); 1284 // Reset and re-enable the hot card cache. 1285 // Note the counts for the cards in the regions in the 1286 // collection set are reset when the collection set is freed. 1287 void reset_hot_card_cache(); 1288 // Free up superfluous code root memory. 1289 void purge_code_root_memory(); 1290 1291 // Rebuild the code root lists for each region 1292 // after a full GC. 1293 void rebuild_code_roots(); 1294 1295 // Performs cleaning of data structures after class unloading. 1296 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); 1297 1298 // Verification 1299 1300 // Perform any cleanup actions necessary before allowing a verification. 1301 void prepare_for_verify() override; 1302 1303 // Perform verification. 1304 1305 // vo == UsePrevMarking -> use "prev" marking information, 1306 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS 1307 // 1308 // NOTE: Only the "prev" marking information is guaranteed to be 1309 // consistent most of the time, so most calls to this should use 1310 // vo == UsePrevMarking. 1311 // Currently there is only one place where this is called with 1312 // vo == UseFullMarking, which is to verify the marking during a 1313 // full GC. 1314 void verify(VerifyOption vo) override; 1315 1316 // WhiteBox testing support. 1317 bool supports_concurrent_gc_breakpoints() const override; 1318 1319 WorkerThreads* safepoint_workers() override { return _workers; } 1320 1321 bool is_archived_object(oop object) const override; 1322 1323 // The methods below are here for convenience and dispatch the 1324 // appropriate method depending on value of the given VerifyOption 1325 // parameter. The values for that parameter, and their meanings, 1326 // are the same as those above. 1327 1328 bool is_obj_dead_cond(const oop obj, 1329 const HeapRegion* hr, 1330 const VerifyOption vo) const; 1331 1332 bool is_obj_dead_cond(const oop obj, 1333 const VerifyOption vo) const; 1334 1335 G1HeapSummary create_g1_heap_summary(); 1336 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1337 1338 // Printing 1339 private: 1340 void print_heap_regions() const; 1341 void print_regions_on(outputStream* st) const; 1342 1343 public: 1344 void print_on(outputStream* st) const override; 1345 void print_extended_on(outputStream* st) const override; 1346 void print_on_error(outputStream* st) const override; 1347 1348 void gc_threads_do(ThreadClosure* tc) const override; 1349 1350 // Override 1351 void print_tracing_info() const override; 1352 1353 // The following two methods are helpful for debugging RSet issues. 1354 void print_cset_rsets() PRODUCT_RETURN; 1355 void print_all_rsets() PRODUCT_RETURN; 1356 1357 // Used to print information about locations in the hs_err file. 1358 bool print_location(outputStream* st, void* addr) const override; 1359 }; 1360 1361 // Scoped object that performs common pre- and post-gc heap printing operations. 1362 class G1HeapPrinterMark : public StackObj { 1363 G1CollectedHeap* _g1h; 1364 G1HeapTransition _heap_transition; 1365 1366 public: 1367 G1HeapPrinterMark(G1CollectedHeap* g1h); 1368 ~G1HeapPrinterMark(); 1369 }; 1370 1371 // Scoped object that performs common pre- and post-gc operations related to 1372 // JFR events. 1373 class G1JFRTracerMark : public StackObj { 1374 protected: 1375 STWGCTimer* _timer; 1376 GCTracer* _tracer; 1377 1378 public: 1379 G1JFRTracerMark(STWGCTimer* timer, GCTracer* tracer); 1380 ~G1JFRTracerMark(); 1381 }; 1382 1383 #endif // SHARE_GC_G1_G1COLLECTEDHEAP_HPP