1 /* 2 * Copyright (c) 2001, 2022, 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/g1MonotonicArenaFreeMemoryTask.hpp" 44 #include "gc/g1/g1MonotonicArenaFreePool.hpp" 45 #include "gc/g1/g1NUMA.hpp" 46 #include "gc/g1/g1SurvivorRegions.hpp" 47 #include "gc/g1/g1YoungGCEvacFailureInjector.hpp" 48 #include "gc/g1/heapRegionManager.hpp" 49 #include "gc/g1/heapRegionSet.hpp" 50 #include "gc/shared/barrierSet.hpp" 51 #include "gc/shared/collectedHeap.hpp" 52 #include "gc/shared/gcHeapSummary.hpp" 53 #include "gc/shared/plab.hpp" 54 #include "gc/shared/softRefPolicy.hpp" 55 #include "gc/shared/taskqueue.hpp" 56 #include "memory/allocation.hpp" 57 #include "memory/iterator.hpp" 58 #include "memory/memRegion.hpp" 59 #include "runtime/mutexLocker.hpp" 60 #include "utilities/bitMap.hpp" 61 62 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 63 // It uses the "Garbage First" heap organization and algorithm, which 64 // may combine concurrent marking with parallel, incremental compaction of 65 // heap subsets that will yield large amounts of garbage. 66 67 // Forward declarations 68 class G1Allocator; 69 class G1ArchiveAllocator; 70 class G1BatchedTask; 71 class G1CardTableEntryClosure; 72 class G1ConcurrentMark; 73 class G1ConcurrentMarkThread; 74 class G1ConcurrentRefine; 75 class G1GCCounters; 76 class G1GCPhaseTimes; 77 class G1HeapSizingPolicy; 78 class G1HotCardCache; 79 class G1NewTracer; 80 class G1RemSet; 81 class G1ServiceTask; 82 class G1ServiceThread; 83 class GCMemoryManager; 84 class HeapRegion; 85 class MemoryPool; 86 class nmethod; 87 class ReferenceProcessor; 88 class STWGCTimer; 89 class WorkerThreads; 90 91 typedef OverflowTaskQueue<ScannerTask, mtGC> G1ScannerTasksQueue; 92 typedef GenericTaskQueueSet<G1ScannerTasksQueue, mtGC> G1ScannerTasksQueueSet; 93 94 typedef int RegionIdx_t; // needs to hold [ 0..max_reserved_regions() ) 95 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 96 97 // The G1 STW is alive closure. 98 // An instance is embedded into the G1CH and used as the 99 // (optional) _is_alive_non_header closure in the STW 100 // reference processor. It is also extensively used during 101 // reference processing during STW evacuation pauses. 102 class G1STWIsAliveClosure : public BoolObjectClosure { 103 G1CollectedHeap* _g1h; 104 public: 105 G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {} 106 bool do_object_b(oop p) override; 107 }; 108 109 class G1STWSubjectToDiscoveryClosure : public BoolObjectClosure { 110 G1CollectedHeap* _g1h; 111 public: 112 G1STWSubjectToDiscoveryClosure(G1CollectedHeap* g1h) : _g1h(g1h) {} 113 bool do_object_b(oop p) override; 114 }; 115 116 class G1RegionMappingChangedListener : public G1MappingChangedListener { 117 private: 118 void reset_from_card_cache(uint start_idx, size_t num_regions); 119 public: 120 void on_commit(uint start_idx, size_t num_regions, bool zero_filled) override; 121 }; 122 123 class G1CollectedHeap : public CollectedHeap { 124 friend class VM_G1CollectForAllocation; 125 friend class VM_G1CollectFull; 126 friend class VM_G1TryInitiateConcMark; 127 friend class VMStructs; 128 friend class MutatorAllocRegion; 129 friend class G1FullCollector; 130 friend class G1GCAllocRegion; 131 friend class G1HeapVerifier; 132 133 friend class G1YoungGCVerifierMark; 134 135 // Closures used in implementation. 136 friend class G1EvacuateRegionsTask; 137 friend class G1PLABAllocator; 138 139 // Other related classes. 140 friend class G1HeapPrinterMark; 141 friend class HeapRegionClaimer; 142 143 // Testing classes. 144 friend class G1CheckRegionAttrTableClosure; 145 146 private: 147 G1ServiceThread* _service_thread; 148 G1ServiceTask* _periodic_gc_task; 149 G1MonotonicArenaFreeMemoryTask* _free_arena_memory_task; 150 151 WorkerThreads* _workers; 152 G1CardTable* _card_table; 153 154 Ticks _collection_pause_end; 155 156 SoftRefPolicy _soft_ref_policy; 157 158 static size_t _humongous_object_threshold_in_words; 159 160 // These sets keep track of old, archive and humongous regions respectively. 161 HeapRegionSet _old_set; 162 HeapRegionSet _archive_set; 163 HeapRegionSet _humongous_set; 164 165 // Young gen memory statistics before GC. 166 G1MonotonicArenaMemoryStats _young_gen_card_set_stats; 167 // Collection set candidates memory statistics after GC. 168 G1MonotonicArenaMemoryStats _collection_set_candidates_card_set_stats; 169 170 // The block offset table for the G1 heap. 171 G1BlockOffsetTable* _bot; 172 173 public: 174 void rebuild_free_region_list(); 175 // Start a new incremental collection set for the next pause. 176 void start_new_collection_set(); 177 178 void prepare_region_for_full_compaction(HeapRegion* hr); 179 180 private: 181 // Rebuilds the region sets / lists so that they are repopulated to 182 // reflect the contents of the heap. The only exception is the 183 // humongous set which was not torn down in the first place. If 184 // free_list_only is true, it will only rebuild the free list. 185 void rebuild_region_sets(bool free_list_only); 186 187 // Callback for region mapping changed events. 188 G1RegionMappingChangedListener _listener; 189 190 // Handle G1 NUMA support. 191 G1NUMA* _numa; 192 193 // The sequence of all heap regions in the heap. 194 HeapRegionManager _hrm; 195 196 // Manages all allocations with regions except humongous object allocations. 197 G1Allocator* _allocator; 198 199 G1YoungGCEvacFailureInjector _evac_failure_injector; 200 201 // Manages all heap verification. 202 G1HeapVerifier* _verifier; 203 204 // Outside of GC pauses, the number of bytes used in all regions other 205 // than the current allocation region(s). 206 volatile size_t _summary_bytes_used; 207 208 void increase_used(size_t bytes); 209 void decrease_used(size_t bytes); 210 211 void set_used(size_t bytes); 212 213 // Number of bytes used in all regions during GC. Typically changed when 214 // retiring a GC alloc region. 215 size_t _bytes_used_during_gc; 216 217 public: 218 size_t bytes_used_during_gc() const { return _bytes_used_during_gc; } 219 220 private: 221 // Class that handles archive allocation ranges. 222 G1ArchiveAllocator* _archive_allocator; 223 224 // GC allocation statistics policy for survivors. 225 G1EvacStats _survivor_evac_stats; 226 227 // GC allocation statistics policy for tenured objects. 228 G1EvacStats _old_evac_stats; 229 230 // Helper for monitoring and management support. 231 G1MonitoringSupport* _monitoring_support; 232 233 uint _num_humongous_objects; // Current amount of (all) humongous objects found in the heap. 234 uint _num_humongous_reclaim_candidates; // Number of humongous object eager reclaim candidates. 235 public: 236 uint num_humongous_objects() const { return _num_humongous_objects; } 237 uint num_humongous_reclaim_candidates() const { return _num_humongous_reclaim_candidates; } 238 bool has_humongous_reclaim_candidates() const { return _num_humongous_reclaim_candidates > 0; } 239 240 void set_humongous_stats(uint num_humongous_total, uint num_humongous_candidates); 241 242 bool should_sample_collection_set_candidates() const; 243 void set_collection_set_candidates_stats(G1MonotonicArenaMemoryStats& stats); 244 void set_young_gen_card_set_stats(const G1MonotonicArenaMemoryStats& stats); 245 246 private: 247 248 G1HRPrinter _hr_printer; 249 250 // Return true if an explicit GC should start a concurrent cycle instead 251 // of doing a STW full GC. A concurrent cycle should be started if: 252 // (a) cause == _g1_humongous_allocation, 253 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent, 254 // (c) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent, 255 // (d) cause == _wb_conc_mark or _wb_breakpoint, 256 // (e) cause == _g1_periodic_collection and +G1PeriodicGCInvokesConcurrent. 257 bool should_do_concurrent_full_gc(GCCause::Cause cause); 258 259 // Attempt to start a concurrent cycle with the indicated cause. 260 // precondition: should_do_concurrent_full_gc(cause) 261 bool try_collect_concurrently(GCCause::Cause cause, 262 uint gc_counter, 263 uint old_marking_started_before); 264 265 // indicates whether we are in young or mixed GC mode 266 G1CollectorState _collector_state; 267 268 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 269 // concurrent cycles) we have started. 270 volatile uint _old_marking_cycles_started; 271 272 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 273 // concurrent cycles) we have completed. 274 volatile uint _old_marking_cycles_completed; 275 276 // This is a non-product method that is helpful for testing. It is 277 // called at the end of a GC and artificially expands the heap by 278 // allocating a number of dead regions. This way we can induce very 279 // frequent marking cycles and stress the cleanup / concurrent 280 // cleanup code more (as all the regions that will be allocated by 281 // this method will be found dead by the marking cycle). 282 void allocate_dummy_regions() PRODUCT_RETURN; 283 284 // Create a memory mapper for auxiliary data structures of the given size and 285 // translation factor. 286 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 287 size_t size, 288 size_t translation_factor); 289 290 void trace_heap(GCWhen::Type when, const GCTracer* tracer) override; 291 292 // These are macros so that, if the assert fires, we get the correct 293 // line number, file, etc. 294 295 #define heap_locking_asserts_params(_extra_message_) \ 296 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 297 (_extra_message_), \ 298 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 299 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 300 BOOL_TO_STR(Thread::current()->is_VM_thread()) 301 302 #define assert_heap_locked() \ 303 do { \ 304 assert(Heap_lock->owned_by_self(), \ 305 heap_locking_asserts_params("should be holding the Heap_lock")); \ 306 } while (0) 307 308 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 309 do { \ 310 assert(Heap_lock->owned_by_self() || \ 311 (SafepointSynchronize::is_at_safepoint() && \ 312 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 313 heap_locking_asserts_params("should be holding the Heap_lock or " \ 314 "should be at a safepoint")); \ 315 } while (0) 316 317 #define assert_heap_locked_and_not_at_safepoint() \ 318 do { \ 319 assert(Heap_lock->owned_by_self() && \ 320 !SafepointSynchronize::is_at_safepoint(), \ 321 heap_locking_asserts_params("should be holding the Heap_lock and " \ 322 "should not be at a safepoint")); \ 323 } while (0) 324 325 #define assert_heap_not_locked() \ 326 do { \ 327 assert(!Heap_lock->owned_by_self(), \ 328 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 329 } while (0) 330 331 #define assert_heap_not_locked_and_not_at_safepoint() \ 332 do { \ 333 assert(!Heap_lock->owned_by_self() && \ 334 !SafepointSynchronize::is_at_safepoint(), \ 335 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 336 "should not be at a safepoint")); \ 337 } while (0) 338 339 #define assert_at_safepoint_on_vm_thread() \ 340 do { \ 341 assert_at_safepoint(); \ 342 assert(Thread::current_or_null() != NULL, "no current thread"); \ 343 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \ 344 } while (0) 345 346 #ifdef ASSERT 347 #define assert_used_and_recalculate_used_equal(g1h) \ 348 do { \ 349 size_t cur_used_bytes = g1h->used(); \ 350 size_t recal_used_bytes = g1h->recalculate_used(); \ 351 assert(cur_used_bytes == recal_used_bytes, "Used(" SIZE_FORMAT ") is not" \ 352 " same as recalculated used(" SIZE_FORMAT ").", \ 353 cur_used_bytes, recal_used_bytes); \ 354 } while (0) 355 #else 356 #define assert_used_and_recalculate_used_equal(g1h) do {} while(0) 357 #endif 358 359 // The young region list. 360 G1EdenRegions _eden; 361 G1SurvivorRegions _survivor; 362 363 STWGCTimer* _gc_timer_stw; 364 365 G1NewTracer* _gc_tracer_stw; 366 367 // The current policy object for the collector. 368 G1Policy* _policy; 369 G1HeapSizingPolicy* _heap_sizing_policy; 370 371 G1CollectionSet _collection_set; 372 373 // Try to allocate a single non-humongous HeapRegion sufficient for 374 // an allocation of the given word_size. If do_expand is true, 375 // attempt to expand the heap if necessary to satisfy the allocation 376 // request. 'type' takes the type of region to be allocated. (Use constants 377 // Old, Eden, Humongous, Survivor defined in HeapRegionType.) 378 HeapRegion* new_region(size_t word_size, 379 HeapRegionType type, 380 bool do_expand, 381 uint node_index = G1NUMA::AnyNodeIndex); 382 383 // Initialize a contiguous set of free regions of length num_regions 384 // and starting at index first so that they appear as a single 385 // humongous region. 386 HeapWord* humongous_obj_allocate_initialize_regions(HeapRegion* first_hr, 387 uint num_regions, 388 size_t word_size); 389 390 // Attempt to allocate a humongous object of the given size. Return 391 // NULL if unsuccessful. 392 HeapWord* humongous_obj_allocate(size_t word_size); 393 394 // The following two methods, allocate_new_tlab() and 395 // mem_allocate(), are the two main entry points from the runtime 396 // into the G1's allocation routines. They have the following 397 // assumptions: 398 // 399 // * They should both be called outside safepoints. 400 // 401 // * They should both be called without holding the Heap_lock. 402 // 403 // * All allocation requests for new TLABs should go to 404 // allocate_new_tlab(). 405 // 406 // * All non-TLAB allocation requests should go to mem_allocate(). 407 // 408 // * If either call cannot satisfy the allocation request using the 409 // current allocating region, they will try to get a new one. If 410 // this fails, they will attempt to do an evacuation pause and 411 // retry the allocation. 412 // 413 // * If all allocation attempts fail, even after trying to schedule 414 // an evacuation pause, allocate_new_tlab() will return NULL, 415 // whereas mem_allocate() will attempt a heap expansion and/or 416 // schedule a Full GC. 417 // 418 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 419 // should never be called with word_size being humongous. All 420 // humongous allocation requests should go to mem_allocate() which 421 // will satisfy them with a special path. 422 423 HeapWord* allocate_new_tlab(size_t min_size, 424 size_t requested_size, 425 size_t* actual_size) override; 426 427 HeapWord* mem_allocate(size_t word_size, 428 bool* gc_overhead_limit_was_exceeded) override; 429 430 // First-level mutator allocation attempt: try to allocate out of 431 // the mutator alloc region without taking the Heap_lock. This 432 // should only be used for non-humongous allocations. 433 inline HeapWord* attempt_allocation(size_t min_word_size, 434 size_t desired_word_size, 435 size_t* actual_word_size); 436 437 // Second-level mutator allocation attempt: take the Heap_lock and 438 // retry the allocation attempt, potentially scheduling a GC 439 // pause. This should only be used for non-humongous allocations. 440 HeapWord* attempt_allocation_slow(size_t word_size); 441 442 // Takes the Heap_lock and attempts a humongous allocation. It can 443 // potentially schedule a GC pause. 444 HeapWord* attempt_allocation_humongous(size_t word_size); 445 446 // Allocation attempt that should be called during safepoints (e.g., 447 // at the end of a successful GC). expect_null_mutator_alloc_region 448 // specifies whether the mutator alloc region is expected to be NULL 449 // or not. 450 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 451 bool expect_null_mutator_alloc_region); 452 453 // These methods are the "callbacks" from the G1AllocRegion class. 454 455 // For mutator alloc regions. 456 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force, uint node_index); 457 void retire_mutator_alloc_region(HeapRegion* alloc_region, 458 size_t allocated_bytes); 459 460 // For GC alloc regions. 461 bool has_more_regions(G1HeapRegionAttr dest); 462 HeapRegion* new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index); 463 void retire_gc_alloc_region(HeapRegion* alloc_region, 464 size_t allocated_bytes, G1HeapRegionAttr dest); 465 466 // - if explicit_gc is true, the GC is for a System.gc() etc, 467 // otherwise it's for a failed allocation. 468 // - if clear_all_soft_refs is true, all soft references should be 469 // cleared during the GC. 470 // - if do_maximal_compaction is true, full gc will do a maximally 471 // compacting collection, leaving no dead wood. 472 // - it returns false if it is unable to do the collection due to the 473 // GC locker being active, true otherwise. 474 bool do_full_collection(bool explicit_gc, 475 bool clear_all_soft_refs, 476 bool do_maximal_compaction); 477 478 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 479 void do_full_collection(bool clear_all_soft_refs) override; 480 481 // Helper to do a full collection that clears soft references. 482 bool upgrade_to_full_collection(); 483 484 // Callback from VM_G1CollectForAllocation operation. 485 // This function does everything necessary/possible to satisfy a 486 // failed allocation request (including collection, expansion, etc.) 487 HeapWord* satisfy_failed_allocation(size_t word_size, 488 bool* succeeded); 489 // Internal helpers used during full GC to split it up to 490 // increase readability. 491 bool abort_concurrent_cycle(); 492 void verify_before_full_collection(bool explicit_gc); 493 void prepare_heap_for_full_collection(); 494 void prepare_heap_for_mutators(); 495 void abort_refinement(); 496 void verify_after_full_collection(); 497 void print_heap_after_full_collection(); 498 499 // Helper method for satisfy_failed_allocation() 500 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 501 bool do_gc, 502 bool maximal_compaction, 503 bool expect_null_mutator_alloc_region, 504 bool* gc_succeeded); 505 506 // Attempting to expand the heap sufficiently 507 // to support an allocation of the given "word_size". If 508 // successful, perform the allocation and return the address of the 509 // allocated block, or else "NULL". 510 HeapWord* expand_and_allocate(size_t word_size); 511 512 void verify_numa_regions(const char* desc); 513 514 public: 515 // If during a concurrent start pause we may install a pending list head which is not 516 // otherwise reachable, ensure that it is marked in the bitmap for concurrent marking 517 // to discover. 518 void make_pending_list_reachable(); 519 520 G1ServiceThread* service_thread() const { return _service_thread; } 521 522 WorkerThreads* workers() const { return _workers; } 523 524 // Run the given batch task using the workers. 525 void run_batch_task(G1BatchedTask* cl); 526 527 // Return "optimal" number of chunks per region we want to use for claiming areas 528 // within a region to claim. 529 // The returned value is a trade-off between granularity of work distribution and 530 // memory usage and maintenance costs of that table. 531 // Testing showed that 64 for 1M/2M region, 128 for 4M/8M regions, 256 for 16/32M regions, 532 // and so on seems to be such a good trade-off. 533 static uint get_chunks_per_region(); 534 535 G1Allocator* allocator() { 536 return _allocator; 537 } 538 539 G1YoungGCEvacFailureInjector* evac_failure_injector() { return &_evac_failure_injector; } 540 541 G1HeapVerifier* verifier() { 542 return _verifier; 543 } 544 545 G1MonitoringSupport* monitoring_support() { 546 assert(_monitoring_support != nullptr, "should have been initialized"); 547 return _monitoring_support; 548 } 549 550 void resize_heap_if_necessary(); 551 552 // Check if there is memory to uncommit and if so schedule a task to do it. 553 void uncommit_regions_if_necessary(); 554 // Immediately uncommit uncommittable regions. 555 uint uncommit_regions(uint region_limit); 556 bool has_uncommittable_regions(); 557 558 G1NUMA* numa() const { return _numa; } 559 560 // Expand the garbage-first heap by at least the given size (in bytes!). 561 // Returns true if the heap was expanded by the requested amount; 562 // false otherwise. 563 // (Rounds up to a HeapRegion boundary.) 564 bool expand(size_t expand_bytes, WorkerThreads* pretouch_workers = NULL, double* expand_time_ms = NULL); 565 bool expand_single_region(uint node_index); 566 567 // Returns the PLAB statistics for a given destination. 568 inline G1EvacStats* alloc_buffer_stats(G1HeapRegionAttr dest); 569 570 // Determines PLAB size for a given destination. 571 inline size_t desired_plab_sz(G1HeapRegionAttr dest); 572 // Clamp the given PLAB word size to allowed values. Prevents humongous PLAB sizes 573 // for two reasons: 574 // * PLABs are allocated using a similar paths as oops, but should 575 // never be in a humongous region 576 // * Allowing humongous PLABs needlessly churns the region free lists 577 inline size_t clamp_plab_size(size_t value) const; 578 579 // Do anything common to GC's. 580 void gc_prologue(bool full); 581 void gc_epilogue(bool full); 582 583 // Does the given region fulfill remembered set based eager reclaim candidate requirements? 584 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const; 585 586 inline bool is_humongous_reclaim_candidate(uint region); 587 588 // Remove from the reclaim candidate set. Also remove from the 589 // collection set so that later encounters avoid the slow path. 590 inline void set_humongous_is_live(oop obj); 591 592 // Register the given region to be part of the collection set. 593 inline void register_humongous_candidate_region_with_region_attr(uint index); 594 595 // We register a region with the fast "in collection set" test. We 596 // simply set to true the array slot corresponding to this region. 597 void register_young_region_with_region_attr(HeapRegion* r) { 598 _region_attr.set_in_young(r->hrm_index()); 599 } 600 inline void register_new_survivor_region_with_region_attr(HeapRegion* r); 601 inline void register_region_with_region_attr(HeapRegion* r); 602 inline void register_old_region_with_region_attr(HeapRegion* r); 603 inline void register_optional_region_with_region_attr(HeapRegion* r); 604 605 void clear_region_attr(const HeapRegion* hr) { 606 _region_attr.clear(hr); 607 } 608 609 void clear_region_attr() { 610 _region_attr.clear(); 611 } 612 613 // Verify that the G1RegionAttr remset tracking corresponds to actual remset tracking 614 // for all regions. 615 void verify_region_attr_remset_is_tracked() PRODUCT_RETURN; 616 617 void clear_bitmap_for_region(HeapRegion* hr); 618 619 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 620 621 // This is called at the start of either a concurrent cycle or a Full 622 // GC to update the number of old marking cycles started. 623 void increment_old_marking_cycles_started(); 624 625 // This is called at the end of either a concurrent cycle or a Full 626 // GC to update the number of old marking cycles completed. Those two 627 // can happen in a nested fashion, i.e., we start a concurrent 628 // cycle, a Full GC happens half-way through it which ends first, 629 // and then the cycle notices that a Full GC happened and ends 630 // too. The concurrent parameter is a boolean to help us do a bit 631 // tighter consistency checking in the method. If concurrent is 632 // false, the caller is the inner caller in the nesting (i.e., the 633 // Full GC). If concurrent is true, the caller is the outer caller 634 // in this nesting (i.e., the concurrent cycle). Further nesting is 635 // not currently supported. The end of this call also notifies 636 // the G1OldGCCount_lock in case a Java thread is waiting for a full 637 // GC to happen (e.g., it called System.gc() with 638 // +ExplicitGCInvokesConcurrent). 639 // whole_heap_examined should indicate that during that old marking 640 // cycle the whole heap has been examined for live objects (as opposed 641 // to only parts, or aborted before completion). 642 void increment_old_marking_cycles_completed(bool concurrent, bool whole_heap_examined); 643 644 uint old_marking_cycles_started() const { 645 return _old_marking_cycles_started; 646 } 647 648 uint old_marking_cycles_completed() const { 649 return _old_marking_cycles_completed; 650 } 651 652 G1HRPrinter* hr_printer() { return &_hr_printer; } 653 654 // Allocates a new heap region instance. 655 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 656 657 // Allocate the highest free region in the reserved heap. This will commit 658 // regions as necessary. 659 HeapRegion* alloc_highest_free_region(); 660 661 // Frees a region by resetting its metadata and adding it to the free list 662 // passed as a parameter (this is usually a local list which will be appended 663 // to the master free list later or NULL if free list management is handled 664 // in another way). 665 // Callers must ensure they are the only one calling free on the given region 666 // at the same time. 667 void free_region(HeapRegion* hr, FreeRegionList* free_list); 668 669 // It dirties the cards that cover the block so that the post 670 // write barrier never queues anything when updating objects on this 671 // block. It is assumed (and in fact we assert) that the block 672 // belongs to a young region. 673 inline void dirty_young_block(HeapWord* start, size_t word_size); 674 675 // Frees a humongous region by collapsing it into individual regions 676 // and calling free_region() for each of them. The freed regions 677 // will be added to the free list that's passed as a parameter (this 678 // is usually a local list which will be appended to the master free 679 // list later). 680 // The method assumes that only a single thread is ever calling 681 // this for a particular region at once. 682 void free_humongous_region(HeapRegion* hr, 683 FreeRegionList* free_list); 684 685 // Facility for allocating in 'archive' regions in high heap memory and 686 // recording the allocated ranges. These should all be called from the 687 // VM thread at safepoints, without the heap lock held. They can be used 688 // to create and archive a set of heap regions which can be mapped at the 689 // same fixed addresses in a subsequent JVM invocation. 690 void begin_archive_alloc_range(bool open = false); 691 692 // Check if the requested size would be too large for an archive allocation. 693 bool is_archive_alloc_too_large(size_t word_size); 694 695 // Allocate memory of the requested size from the archive region. This will 696 // return NULL if the size is too large or if no memory is available. It 697 // does not trigger a garbage collection. 698 HeapWord* archive_mem_allocate(size_t word_size); 699 700 // Optionally aligns the end address and returns the allocated ranges in 701 // an array of MemRegions in order of ascending addresses. 702 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 703 size_t end_alignment_in_bytes = 0); 704 705 // Facility for allocating a fixed range within the heap and marking 706 // the containing regions as 'archive'. For use at JVM init time, when the 707 // caller may mmap archived heap data at the specified range(s). 708 // Verify that the MemRegions specified in the argument array are within the 709 // reserved heap. 710 bool check_archive_addresses(MemRegion* range, size_t count); 711 712 // Commit the appropriate G1 regions containing the specified MemRegions 713 // and mark them as 'archive' regions. The regions in the array must be 714 // non-overlapping and in order of ascending address. 715 bool alloc_archive_regions(MemRegion* range, size_t count, bool open); 716 717 // Insert any required filler objects in the G1 regions around the specified 718 // ranges to make the regions parseable. This must be called after 719 // alloc_archive_regions, and after class loading has occurred. 720 void fill_archive_regions(MemRegion* range, size_t count); 721 722 // Populate the G1BlockOffsetTablePart for archived regions with the given 723 // memory ranges. 724 void populate_archive_regions_bot_part(MemRegion* range, size_t count); 725 726 // For each of the specified MemRegions, uncommit the containing G1 regions 727 // which had been allocated by alloc_archive_regions. This should be called 728 // rather than fill_archive_regions at JVM init time if the archive file 729 // mapping failed, with the same non-overlapping and sorted MemRegion array. 730 void dealloc_archive_regions(MemRegion* range, size_t count); 731 732 private: 733 734 // Shrink the garbage-first heap by at most the given size (in bytes!). 735 // (Rounds down to a HeapRegion boundary.) 736 void shrink(size_t shrink_bytes); 737 void shrink_helper(size_t expand_bytes); 738 739 // Schedule the VM operation that will do an evacuation pause to 740 // satisfy an allocation request of word_size. *succeeded will 741 // return whether the VM operation was successful (it did do an 742 // evacuation pause) or not (another thread beat us to it or the GC 743 // locker was active). Given that we should not be holding the 744 // Heap_lock when we enter this method, we will pass the 745 // gc_count_before (i.e., total_collections()) as a parameter since 746 // it has to be read while holding the Heap_lock. Currently, both 747 // methods that call do_collection_pause() release the Heap_lock 748 // before the call, so it's easy to read gc_count_before just before. 749 HeapWord* do_collection_pause(size_t word_size, 750 uint gc_count_before, 751 bool* succeeded, 752 GCCause::Cause gc_cause); 753 754 // Perform an incremental collection at a safepoint, possibly 755 // followed by a by-policy upgrade to a full collection. Returns 756 // false if unable to do the collection due to the GC locker being 757 // active, true otherwise. 758 // precondition: at safepoint on VM thread 759 // precondition: !is_gc_active() 760 bool do_collection_pause_at_safepoint(); 761 762 // Helper for do_collection_pause_at_safepoint, containing the guts 763 // of the incremental collection pause, executed by the vm thread. 764 void do_collection_pause_at_safepoint_helper(); 765 766 G1HeapVerifier::G1VerifyType young_collection_verify_type() const; 767 void verify_before_young_collection(G1HeapVerifier::G1VerifyType type); 768 void verify_after_young_collection(G1HeapVerifier::G1VerifyType type); 769 770 public: 771 // Start a concurrent cycle. 772 void start_concurrent_cycle(bool concurrent_operation_is_full_mark); 773 774 void prepare_tlabs_for_mutator(); 775 776 void retire_tlabs(); 777 778 void expand_heap_after_young_collection(); 779 // Update object copying statistics. 780 void record_obj_copy_mem_stats(); 781 782 private: 783 // The hot card cache for remembered set insertion optimization. 784 G1HotCardCache* _hot_card_cache; 785 786 // The g1 remembered set of the heap. 787 G1RemSet* _rem_set; 788 // Global card set configuration 789 G1CardSetConfiguration _card_set_config; 790 791 G1MonotonicArenaFreePool _card_set_freelist_pool; 792 793 public: 794 // After a collection pause, reset eden and the collection set. 795 void clear_eden(); 796 void clear_collection_set(); 797 798 // Abandon the current collection set without recording policy 799 // statistics or updating free lists. 800 void abandon_collection_set(G1CollectionSet* collection_set); 801 802 // The concurrent marker (and the thread it runs in.) 803 G1ConcurrentMark* _cm; 804 G1ConcurrentMarkThread* _cm_thread; 805 806 // The concurrent refiner. 807 G1ConcurrentRefine* _cr; 808 809 // The parallel task queues 810 G1ScannerTasksQueueSet *_task_queues; 811 812 // ("Weak") Reference processing support. 813 // 814 // G1 has 2 instances of the reference processor class. 815 // 816 // One (_ref_processor_cm) handles reference object discovery and subsequent 817 // processing during concurrent marking cycles. Discovery is enabled/disabled 818 // at the start/end of a concurrent marking cycle. 819 // 820 // The other (_ref_processor_stw) handles reference object discovery and 821 // processing during incremental evacuation pauses and full GC pauses. 822 // 823 // ## Incremental evacuation pauses 824 // 825 // STW ref processor discovery is enabled/disabled at the start/end of an 826 // incremental evacuation pause. No particular handling of the CM ref 827 // processor is needed, apart from treating the discovered references as 828 // roots; CM discovery does not need to be temporarily disabled as all 829 // marking threads are paused during incremental evacuation pauses. 830 // 831 // ## Full GC pauses 832 // 833 // We abort any ongoing concurrent marking cycle, disable CM discovery, and 834 // temporarily substitute a new closure for the STW ref processor's 835 // _is_alive_non_header field (old value is restored after the full GC). Then 836 // STW ref processor discovery is enabled, and marking & compaction 837 // commences. 838 839 // The (stw) reference processor... 840 ReferenceProcessor* _ref_processor_stw; 841 842 // During reference object discovery, the _is_alive_non_header 843 // closure (if non-null) is applied to the referent object to 844 // determine whether the referent is live. If so then the 845 // reference object does not need to be 'discovered' and can 846 // be treated as a regular oop. This has the benefit of reducing 847 // the number of 'discovered' reference objects that need to 848 // be processed. 849 // 850 // Instance of the is_alive closure for embedding into the 851 // STW reference processor as the _is_alive_non_header field. 852 // Supplying a value for the _is_alive_non_header field is 853 // optional but doing so prevents unnecessary additions to 854 // the discovered lists during reference discovery. 855 G1STWIsAliveClosure _is_alive_closure_stw; 856 857 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw; 858 859 // The (concurrent marking) reference processor... 860 ReferenceProcessor* _ref_processor_cm; 861 862 // Instance of the concurrent mark is_alive closure for embedding 863 // into the Concurrent Marking reference processor as the 864 // _is_alive_non_header field. Supplying a value for the 865 // _is_alive_non_header field is optional but doing so prevents 866 // unnecessary additions to the discovered lists during reference 867 // discovery. 868 G1CMIsAliveClosure _is_alive_closure_cm; 869 870 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm; 871 public: 872 873 G1ScannerTasksQueueSet* task_queues() const; 874 G1ScannerTasksQueue* task_queue(uint i) const; 875 876 // Create a G1CollectedHeap. 877 // Must call the initialize method afterwards. 878 // May not return if something goes wrong. 879 G1CollectedHeap(); 880 881 private: 882 jint initialize_concurrent_refinement(); 883 jint initialize_service_thread(); 884 public: 885 // Initialize the G1CollectedHeap to have the initial and 886 // maximum sizes and remembered and barrier sets 887 // specified by the policy object. 888 jint initialize() override; 889 890 // Returns whether concurrent mark threads (and the VM) are about to terminate. 891 bool concurrent_mark_is_terminating() const; 892 893 void stop() override; 894 void safepoint_synchronize_begin() override; 895 void safepoint_synchronize_end() override; 896 897 // Does operations required after initialization has been done. 898 void post_initialize() override; 899 900 // Initialize weak reference processing. 901 void ref_processing_init(); 902 903 Name kind() const override { 904 return CollectedHeap::G1; 905 } 906 907 const char* name() const override { 908 return "G1"; 909 } 910 911 const G1CollectorState* collector_state() const { return &_collector_state; } 912 G1CollectorState* collector_state() { return &_collector_state; } 913 914 // The current policy object for the collector. 915 G1Policy* policy() const { return _policy; } 916 // The remembered set. 917 G1RemSet* rem_set() const { return _rem_set; } 918 919 const G1MonotonicArenaFreePool* card_set_freelist_pool() const { return &_card_set_freelist_pool; } 920 G1MonotonicArenaFreePool* card_set_freelist_pool() { return &_card_set_freelist_pool; } 921 922 inline G1GCPhaseTimes* phase_times() const; 923 924 const G1CollectionSet* collection_set() const { return &_collection_set; } 925 G1CollectionSet* collection_set() { return &_collection_set; } 926 927 SoftRefPolicy* soft_ref_policy() override; 928 929 void initialize_serviceability() override; 930 MemoryUsage memory_usage() override; 931 GrowableArray<GCMemoryManager*> memory_managers() override; 932 GrowableArray<MemoryPool*> memory_pools() override; 933 934 void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) override; 935 936 static void start_codecache_marking_cycle_if_inactive(); 937 938 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 939 void iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id); 940 941 // The shared block offset table array. 942 G1BlockOffsetTable* bot() const { return _bot; } 943 944 // Reference Processing accessors 945 946 // The STW reference processor.... 947 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 948 949 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 950 STWGCTimer* gc_timer_stw() const { return _gc_timer_stw; } 951 952 // The Concurrent Marking reference processor... 953 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 954 955 size_t unused_committed_regions_in_bytes() const; 956 957 size_t capacity() const override; 958 size_t used() const override; 959 // This should be called when we're not holding the heap lock. The 960 // result might be a bit inaccurate. 961 size_t used_unlocked() const; 962 size_t recalculate_used() const; 963 964 // These virtual functions do the actual allocation. 965 // Some heaps may offer a contiguous region for shared non-blocking 966 // allocation, via inlined code (by exporting the address of the top and 967 // end fields defining the extent of the contiguous allocation region.) 968 // But G1CollectedHeap doesn't yet support this. 969 970 bool is_maximal_no_gc() const override { 971 return _hrm.available() == 0; 972 } 973 974 // Returns true if an incremental GC should be upgrade to a full gc. This 975 // is done when there are no free regions and the heap can't be expanded. 976 bool should_upgrade_to_full_gc() const { 977 return is_maximal_no_gc() && num_free_regions() == 0; 978 } 979 980 // The current number of regions in the heap. 981 uint num_regions() const { return _hrm.length(); } 982 983 // The max number of regions reserved for the heap. Except for static array 984 // sizing purposes you probably want to use max_regions(). 985 uint max_reserved_regions() const { return _hrm.reserved_length(); } 986 987 // Max number of regions that can be committed. 988 uint max_regions() const { return _hrm.max_length(); } 989 990 // The number of regions that are completely free. 991 uint num_free_regions() const { return _hrm.num_free_regions(); } 992 993 // The number of regions that can be allocated into. 994 uint num_free_or_available_regions() const { return num_free_regions() + _hrm.available(); } 995 996 MemoryUsage get_auxiliary_data_memory_usage() const { 997 return _hrm.get_auxiliary_data_memory_usage(); 998 } 999 1000 // The number of regions that are not completely free. 1001 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1002 1003 #ifdef ASSERT 1004 bool is_on_master_free_list(HeapRegion* hr) { 1005 return _hrm.is_free(hr); 1006 } 1007 #endif // ASSERT 1008 1009 inline void old_set_add(HeapRegion* hr); 1010 inline void old_set_remove(HeapRegion* hr); 1011 1012 inline void archive_set_add(HeapRegion* hr); 1013 1014 size_t non_young_capacity_bytes() { 1015 return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes; 1016 } 1017 1018 // Determine whether the given region is one that we are using as an 1019 // old GC alloc region. 1020 bool is_old_gc_alloc_region(HeapRegion* hr); 1021 1022 // Perform a collection of the heap; intended for use in implementing 1023 // "System.gc". This probably implies as full a collection as the 1024 // "CollectedHeap" supports. 1025 void collect(GCCause::Cause cause) override; 1026 1027 // Perform a collection of the heap with the given cause. 1028 // Returns whether this collection actually executed. 1029 bool try_collect(GCCause::Cause cause, const G1GCCounters& counters_before); 1030 1031 void start_concurrent_gc_for_metadata_allocation(GCCause::Cause gc_cause); 1032 1033 void remove_from_old_gen_sets(const uint old_regions_removed, 1034 const uint archive_regions_removed, 1035 const uint humongous_regions_removed); 1036 void prepend_to_freelist(FreeRegionList* list); 1037 void decrement_summary_bytes(size_t bytes); 1038 1039 bool is_in(const void* p) const override; 1040 1041 // Return "TRUE" iff the given object address is within the collection 1042 // set. Assumes that the reference points into the heap. 1043 inline bool is_in_cset(const HeapRegion *hr) const; 1044 inline bool is_in_cset(oop obj) const; 1045 inline bool is_in_cset(HeapWord* addr) const; 1046 1047 inline bool is_in_cset_or_humongous_candidate(const oop obj); 1048 1049 private: 1050 // This array is used for a quick test on whether a reference points into 1051 // the collection set or not. Each of the array's elements denotes whether the 1052 // corresponding region is in the collection set or not. 1053 G1HeapRegionAttrBiasedMappedArray _region_attr; 1054 1055 public: 1056 1057 inline G1HeapRegionAttr region_attr(const void* obj) const; 1058 inline G1HeapRegionAttr region_attr(uint idx) const; 1059 1060 MemRegion reserved() const { 1061 return _hrm.reserved(); 1062 } 1063 1064 bool is_in_reserved(const void* addr) const { 1065 return reserved().contains(addr); 1066 } 1067 1068 G1HotCardCache* hot_card_cache() const { return _hot_card_cache; } 1069 1070 G1CardTable* card_table() const { 1071 return _card_table; 1072 } 1073 1074 // Iteration functions. 1075 1076 void object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer); 1077 1078 // Iterate over all objects, calling "cl.do_object" on each. 1079 void object_iterate(ObjectClosure* cl) override; 1080 1081 ParallelObjectIteratorImpl* parallel_object_iterator(uint thread_num) override; 1082 1083 // Keep alive an object that was loaded with AS_NO_KEEPALIVE. 1084 void keep_alive(oop obj) override; 1085 1086 // Iterate over heap regions, in address order, terminating the 1087 // iteration early if the "do_heap_region" method returns "true". 1088 void heap_region_iterate(HeapRegionClosure* blk) const; 1089 void heap_region_iterate(HeapRegionIndexClosure* blk) const; 1090 1091 // Return the region with the given index. It assumes the index is valid. 1092 inline HeapRegion* region_at(uint index) const; 1093 inline HeapRegion* region_at_or_null(uint index) const; 1094 1095 // Return the next region (by index) that is part of the same 1096 // humongous object that hr is part of. 1097 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1098 1099 // Calculate the region index of the given address. Given address must be 1100 // within the heap. 1101 inline uint addr_to_region(const void* addr) const; 1102 1103 inline HeapWord* bottom_addr_for_region(uint index) const; 1104 1105 // Two functions to iterate over the heap regions in parallel. Threads 1106 // compete using the HeapRegionClaimer to claim the regions before 1107 // applying the closure on them. 1108 // The _from_worker_offset version uses the HeapRegionClaimer and 1109 // the worker id to calculate a start offset to prevent all workers to 1110 // start from the point. 1111 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 1112 HeapRegionClaimer* hrclaimer, 1113 uint worker_id) const; 1114 1115 void heap_region_par_iterate_from_start(HeapRegionClosure* cl, 1116 HeapRegionClaimer* hrclaimer) const; 1117 1118 // Iterate over all regions in the collection set in parallel. 1119 void collection_set_par_iterate_all(HeapRegionClosure* cl, 1120 HeapRegionClaimer* hr_claimer, 1121 uint worker_id); 1122 1123 // Iterate over all regions currently in the current collection set. 1124 void collection_set_iterate_all(HeapRegionClosure* blk); 1125 1126 // Iterate over the regions in the current increment of the collection set. 1127 // Starts the iteration so that the start regions of a given worker id over the 1128 // set active_workers are evenly spread across the set of collection set regions 1129 // to be iterated. 1130 // The variant with the HeapRegionClaimer guarantees that the closure will be 1131 // applied to a particular region exactly once. 1132 void collection_set_iterate_increment_from(HeapRegionClosure *blk, uint worker_id) { 1133 collection_set_iterate_increment_from(blk, NULL, worker_id); 1134 } 1135 void collection_set_iterate_increment_from(HeapRegionClosure *blk, HeapRegionClaimer* hr_claimer, uint worker_id); 1136 // Iterate over the array of region indexes, uint regions[length], applying 1137 // the given HeapRegionClosure on each region. The worker_id will determine where 1138 // to start the iteration to allow for more efficient parallel iteration. 1139 void par_iterate_regions_array(HeapRegionClosure* cl, 1140 HeapRegionClaimer* hr_claimer, 1141 const uint regions[], 1142 size_t length, 1143 uint worker_id) const; 1144 1145 // Returns the HeapRegion that contains addr. addr must not be nullptr. 1146 inline HeapRegion* heap_region_containing(const void* addr) const; 1147 1148 // Returns the HeapRegion that contains addr, or nullptr if that is an uncommitted 1149 // region. addr must not be nullptr. 1150 inline HeapRegion* heap_region_containing_or_null(const void* addr) const; 1151 1152 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1153 // each address in the (reserved) heap is a member of exactly 1154 // one block. The defining characteristic of a block is that it is 1155 // possible to find its size, and thus to progress forward to the next 1156 // block. (Blocks may be of different sizes.) Thus, blocks may 1157 // represent Java objects, or they might be free blocks in a 1158 // free-list-based heap (or subheap), as long as the two kinds are 1159 // distinguishable and the size of each is determinable. 1160 1161 // Returns the address of the start of the "block" that contains the 1162 // address "addr". We say "blocks" instead of "object" since some heaps 1163 // may not pack objects densely; a chunk may either be an object or a 1164 // non-object. 1165 HeapWord* block_start(const void* addr) const; 1166 1167 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1168 // the block is an object. 1169 bool block_is_obj(const HeapWord* addr) const; 1170 1171 // Section on thread-local allocation buffers (TLABs) 1172 // See CollectedHeap for semantics. 1173 1174 size_t tlab_capacity(Thread* ignored) const override; 1175 size_t tlab_used(Thread* ignored) const override; 1176 size_t max_tlab_size() const override; 1177 size_t unsafe_max_tlab_alloc(Thread* ignored) const override; 1178 1179 inline bool is_in_young(const oop obj) const; 1180 inline bool requires_barriers(stackChunkOop obj) const override; 1181 1182 // Returns "true" iff the given word_size is "very large". 1183 static bool is_humongous(size_t word_size) { 1184 // Note this has to be strictly greater-than as the TLABs 1185 // are capped at the humongous threshold and we want to 1186 // ensure that we don't try to allocate a TLAB as 1187 // humongous and that we don't allocate a humongous 1188 // object in a TLAB. 1189 return word_size > _humongous_object_threshold_in_words; 1190 } 1191 1192 // Returns the humongous threshold for a specific region size 1193 static size_t humongous_threshold_for(size_t region_size) { 1194 return (region_size / 2); 1195 } 1196 1197 // Returns the number of regions the humongous object of the given word size 1198 // requires. 1199 static size_t humongous_obj_size_in_regions(size_t word_size); 1200 1201 // Print the maximum heap capacity. 1202 size_t max_capacity() const override; 1203 1204 Tickspan time_since_last_collection() const { return Ticks::now() - _collection_pause_end; } 1205 1206 // Convenience function to be used in situations where the heap type can be 1207 // asserted to be this type. 1208 static G1CollectedHeap* heap() { 1209 return named_heap<G1CollectedHeap>(CollectedHeap::G1); 1210 } 1211 1212 void set_region_short_lived_locked(HeapRegion* hr); 1213 // add appropriate methods for any other surv rate groups 1214 1215 G1SurvivorRegions* survivor() { return &_survivor; } 1216 1217 uint eden_regions_count() const { return _eden.length(); } 1218 uint eden_regions_count(uint node_index) const { return _eden.regions_on_node(node_index); } 1219 uint survivor_regions_count() const { return _survivor.length(); } 1220 uint survivor_regions_count(uint node_index) const { return _survivor.regions_on_node(node_index); } 1221 size_t eden_regions_used_bytes() const { return _eden.used_bytes(); } 1222 size_t survivor_regions_used_bytes() const { return _survivor.used_bytes(); } 1223 uint young_regions_count() const { return _eden.length() + _survivor.length(); } 1224 uint old_regions_count() const { return _old_set.length(); } 1225 uint archive_regions_count() const { return _archive_set.length(); } 1226 uint humongous_regions_count() const { return _humongous_set.length(); } 1227 1228 #ifdef ASSERT 1229 bool check_young_list_empty(); 1230 #endif 1231 1232 bool is_marked(oop obj) const; 1233 1234 inline static bool is_obj_filler(const oop obj); 1235 // Determine if an object is dead, given the object and also 1236 // the region to which the object belongs. 1237 inline bool is_obj_dead(const oop obj, const HeapRegion* hr) const; 1238 1239 // Determine if an object is dead, given only the object itself. 1240 // This will find the region to which the object belongs and 1241 // then call the region version of the same function. 1242 // If obj is NULL it is not dead. 1243 inline bool is_obj_dead(const oop obj) const; 1244 1245 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const; 1246 inline bool is_obj_dead_full(const oop obj) const; 1247 1248 // Mark the live object that failed evacuation in the bitmap. 1249 void mark_evac_failure_object(uint worker_id, oop obj, size_t obj_size) const; 1250 1251 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1252 1253 // Refinement 1254 1255 G1ConcurrentRefine* concurrent_refine() const { return _cr; } 1256 1257 // Optimized nmethod scanning support routines 1258 1259 // Register the given nmethod with the G1 heap. 1260 void register_nmethod(nmethod* nm) override; 1261 1262 // Unregister the given nmethod from the G1 heap. 1263 void unregister_nmethod(nmethod* nm) override; 1264 1265 // No nmethod verification implemented. 1266 void verify_nmethod(nmethod* nm) override {} 1267 1268 // Recalculate amount of used memory after GC. Must be called after all allocation 1269 // has finished. 1270 void update_used_after_gc(bool evacuation_failed); 1271 // Reset and re-enable the hot card cache. 1272 // Note the counts for the cards in the regions in the 1273 // collection set are reset when the collection set is freed. 1274 void reset_hot_card_cache(); 1275 // Free up superfluous code root memory. 1276 void purge_code_root_memory(); 1277 1278 // Rebuild the code root lists for each region 1279 // after a full GC. 1280 void rebuild_code_roots(); 1281 1282 // Performs cleaning of data structures after class unloading. 1283 void complete_cleaning(bool class_unloading_occurred); 1284 1285 // Verification 1286 1287 // Perform any cleanup actions necessary before allowing a verification. 1288 void prepare_for_verify() override; 1289 1290 // Perform verification. 1291 void verify(VerifyOption vo) override; 1292 1293 // WhiteBox testing support. 1294 bool supports_concurrent_gc_breakpoints() const override; 1295 1296 WorkerThreads* safepoint_workers() override { return _workers; } 1297 1298 bool is_archived_object(oop object) const override; 1299 1300 // The methods below are here for convenience and dispatch the 1301 // appropriate method depending on value of the given VerifyOption 1302 // parameter. The values for that parameter, and their meanings, 1303 // are the same as those above. 1304 1305 bool is_obj_dead_cond(const oop obj, 1306 const HeapRegion* hr, 1307 const VerifyOption vo) const; 1308 1309 bool is_obj_dead_cond(const oop obj, 1310 const VerifyOption vo) const; 1311 1312 G1HeapSummary create_g1_heap_summary(); 1313 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1314 1315 // Printing 1316 private: 1317 void print_heap_regions() const; 1318 void print_regions_on(outputStream* st) const; 1319 1320 public: 1321 void print_on(outputStream* st) const override; 1322 void print_extended_on(outputStream* st) const override; 1323 void print_on_error(outputStream* st) const override; 1324 1325 void gc_threads_do(ThreadClosure* tc) const override; 1326 1327 // Override 1328 void print_tracing_info() const override; 1329 1330 // The following two methods are helpful for debugging RSet issues. 1331 void print_cset_rsets() PRODUCT_RETURN; 1332 void print_all_rsets() PRODUCT_RETURN; 1333 1334 // Used to print information about locations in the hs_err file. 1335 bool print_location(outputStream* st, void* addr) const override; 1336 }; 1337 1338 // Scoped object that performs common pre- and post-gc heap printing operations. 1339 class G1HeapPrinterMark : public StackObj { 1340 G1CollectedHeap* _g1h; 1341 G1HeapTransition _heap_transition; 1342 1343 public: 1344 G1HeapPrinterMark(G1CollectedHeap* g1h); 1345 ~G1HeapPrinterMark(); 1346 }; 1347 1348 // Scoped object that performs common pre- and post-gc operations related to 1349 // JFR events. 1350 class G1JFRTracerMark : public StackObj { 1351 protected: 1352 STWGCTimer* _timer; 1353 GCTracer* _tracer; 1354 1355 public: 1356 G1JFRTracerMark(STWGCTimer* timer, GCTracer* tracer); 1357 ~G1JFRTracerMark(); 1358 }; 1359 1360 #endif // SHARE_GC_G1_G1COLLECTEDHEAP_HPP