1 /* 2 * Copyright (c) 2001, 2023, 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 "runtime/threadSMR.hpp" 61 #include "utilities/bitMap.hpp" 62 63 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 64 // It uses the "Garbage First" heap organization and algorithm, which 65 // may combine concurrent marking with parallel, incremental compaction of 66 // heap subsets that will yield large amounts of garbage. 67 68 // Forward declarations 69 class G1Allocator; 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 G1NewTracer; 79 class G1RemSet; 80 class G1ServiceTask; 81 class G1ServiceThread; 82 class GCMemoryManager; 83 class HeapRegion; 84 class MemoryPool; 85 class nmethod; 86 class ReferenceProcessor; 87 class STWGCTimer; 88 class SlidingForwarding; 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 // Helper to claim contiguous sets of JavaThread for processing by multiple threads. 124 class G1JavaThreadsListClaimer : public StackObj { 125 ThreadsListHandle _list; 126 uint _claim_step; 127 128 volatile uint _cur_claim; 129 130 // Attempts to claim _claim_step JavaThreads, returning an array of claimed 131 // JavaThread* with count elements. Returns null (and a zero count) if there 132 // are no more threads to claim. 133 JavaThread* const* claim(uint& count); 134 135 public: 136 G1JavaThreadsListClaimer(uint claim_step) : _list(), _claim_step(claim_step), _cur_claim(0) { 137 assert(claim_step > 0, "must be"); 138 } 139 140 // Executes the given closure on the elements of the JavaThread list, chunking the 141 // JavaThread set in claim_step chunks for each caller to reduce parallelization 142 // overhead. 143 void apply(ThreadClosure* cl); 144 145 // Total number of JavaThreads that can be claimed. 146 uint length() const { return _list.length(); } 147 }; 148 149 class G1CollectedHeap : public CollectedHeap { 150 friend class VM_G1CollectForAllocation; 151 friend class VM_G1CollectFull; 152 friend class VM_G1TryInitiateConcMark; 153 friend class VMStructs; 154 friend class MutatorAllocRegion; 155 friend class G1FullCollector; 156 friend class G1GCAllocRegion; 157 friend class G1HeapVerifier; 158 159 friend class G1YoungGCVerifierMark; 160 161 // Closures used in implementation. 162 friend class G1EvacuateRegionsTask; 163 friend class G1PLABAllocator; 164 165 // Other related classes. 166 friend class G1HeapPrinterMark; 167 friend class HeapRegionClaimer; 168 169 // Testing classes. 170 friend class G1CheckRegionAttrTableClosure; 171 172 private: 173 G1ServiceThread* _service_thread; 174 G1ServiceTask* _periodic_gc_task; 175 G1MonotonicArenaFreeMemoryTask* _free_arena_memory_task; 176 177 WorkerThreads* _workers; 178 G1CardTable* _card_table; 179 180 Ticks _collection_pause_end; 181 182 SoftRefPolicy _soft_ref_policy; 183 184 static size_t _humongous_object_threshold_in_words; 185 186 // These sets keep track of old, archive and humongous regions respectively. 187 HeapRegionSet _old_set; 188 HeapRegionSet _archive_set; 189 HeapRegionSet _humongous_set; 190 191 // Young gen memory statistics before GC. 192 G1MonotonicArenaMemoryStats _young_gen_card_set_stats; 193 // Collection set candidates memory statistics after GC. 194 G1MonotonicArenaMemoryStats _collection_set_candidates_card_set_stats; 195 196 // The block offset table for the G1 heap. 197 G1BlockOffsetTable* _bot; 198 199 public: 200 void rebuild_free_region_list(); 201 // Start a new incremental collection set for the next pause. 202 void start_new_collection_set(); 203 204 void prepare_region_for_full_compaction(HeapRegion* hr); 205 206 private: 207 // Rebuilds the region sets / lists so that they are repopulated to 208 // reflect the contents of the heap. The only exception is the 209 // humongous set which was not torn down in the first place. If 210 // free_list_only is true, it will only rebuild the free list. 211 void rebuild_region_sets(bool free_list_only); 212 213 // Callback for region mapping changed events. 214 G1RegionMappingChangedListener _listener; 215 216 // Handle G1 NUMA support. 217 G1NUMA* _numa; 218 219 // The sequence of all heap regions in the heap. 220 HeapRegionManager _hrm; 221 222 // Manages all allocations with regions except humongous object allocations. 223 G1Allocator* _allocator; 224 225 G1YoungGCEvacFailureInjector _evac_failure_injector; 226 227 // Manages all heap verification. 228 G1HeapVerifier* _verifier; 229 230 // Outside of GC pauses, the number of bytes used in all regions other 231 // than the current allocation region(s). 232 volatile size_t _summary_bytes_used; 233 234 void increase_used(size_t bytes); 235 void decrease_used(size_t bytes); 236 237 void set_used(size_t bytes); 238 239 // Number of bytes used in all regions during GC. Typically changed when 240 // retiring a GC alloc region. 241 size_t _bytes_used_during_gc; 242 243 public: 244 size_t bytes_used_during_gc() const { return _bytes_used_during_gc; } 245 246 private: 247 // GC allocation statistics policy for survivors. 248 G1EvacStats _survivor_evac_stats; 249 250 // GC allocation statistics policy for tenured objects. 251 G1EvacStats _old_evac_stats; 252 253 // Helper for monitoring and management support. 254 G1MonitoringSupport* _monitoring_support; 255 256 SlidingForwarding* _forwarding; 257 258 uint _num_humongous_objects; // Current amount of (all) humongous objects found in the heap. 259 uint _num_humongous_reclaim_candidates; // Number of humongous object eager reclaim candidates. 260 public: 261 uint num_humongous_objects() const { return _num_humongous_objects; } 262 uint num_humongous_reclaim_candidates() const { return _num_humongous_reclaim_candidates; } 263 bool has_humongous_reclaim_candidates() const { return _num_humongous_reclaim_candidates > 0; } 264 265 void set_humongous_stats(uint num_humongous_total, uint num_humongous_candidates); 266 267 bool should_sample_collection_set_candidates() const; 268 void set_collection_set_candidates_stats(G1MonotonicArenaMemoryStats& stats); 269 void set_young_gen_card_set_stats(const G1MonotonicArenaMemoryStats& stats); 270 271 SlidingForwarding* forwarding() const { 272 return _forwarding; 273 } 274 275 private: 276 277 G1HRPrinter _hr_printer; 278 279 // Return true if an explicit GC should start a concurrent cycle instead 280 // of doing a STW full GC. A concurrent cycle should be started if: 281 // (a) cause == _g1_humongous_allocation, 282 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent, 283 // (c) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent, 284 // (d) cause == _wb_breakpoint, 285 // (e) cause == _g1_periodic_collection and +G1PeriodicGCInvokesConcurrent. 286 bool should_do_concurrent_full_gc(GCCause::Cause cause); 287 288 // Attempt to start a concurrent cycle with the indicated cause. 289 // precondition: should_do_concurrent_full_gc(cause) 290 bool try_collect_concurrently(GCCause::Cause cause, 291 uint gc_counter, 292 uint old_marking_started_before); 293 294 // indicates whether we are in young or mixed GC mode 295 G1CollectorState _collector_state; 296 297 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 298 // concurrent cycles) we have started. 299 volatile uint _old_marking_cycles_started; 300 301 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 302 // concurrent cycles) we have completed. 303 volatile uint _old_marking_cycles_completed; 304 305 // Create a memory mapper for auxiliary data structures of the given size and 306 // translation factor. 307 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 308 size_t size, 309 size_t translation_factor); 310 311 void trace_heap(GCWhen::Type when, const GCTracer* tracer) override; 312 313 // These are macros so that, if the assert fires, we get the correct 314 // line number, file, etc. 315 316 #define heap_locking_asserts_params(_extra_message_) \ 317 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 318 (_extra_message_), \ 319 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 320 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 321 BOOL_TO_STR(Thread::current()->is_VM_thread()) 322 323 #define assert_heap_locked() \ 324 do { \ 325 assert(Heap_lock->owned_by_self(), \ 326 heap_locking_asserts_params("should be holding the Heap_lock")); \ 327 } while (0) 328 329 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 330 do { \ 331 assert(Heap_lock->owned_by_self() || \ 332 (SafepointSynchronize::is_at_safepoint() && \ 333 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 334 heap_locking_asserts_params("should be holding the Heap_lock or " \ 335 "should be at a safepoint")); \ 336 } while (0) 337 338 #define assert_heap_locked_and_not_at_safepoint() \ 339 do { \ 340 assert(Heap_lock->owned_by_self() && \ 341 !SafepointSynchronize::is_at_safepoint(), \ 342 heap_locking_asserts_params("should be holding the Heap_lock and " \ 343 "should not be at a safepoint")); \ 344 } while (0) 345 346 #define assert_heap_not_locked() \ 347 do { \ 348 assert(!Heap_lock->owned_by_self(), \ 349 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 350 } while (0) 351 352 #define assert_heap_not_locked_and_not_at_safepoint() \ 353 do { \ 354 assert(!Heap_lock->owned_by_self() && \ 355 !SafepointSynchronize::is_at_safepoint(), \ 356 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 357 "should not be at a safepoint")); \ 358 } while (0) 359 360 #define assert_at_safepoint_on_vm_thread() \ 361 do { \ 362 assert_at_safepoint(); \ 363 assert(Thread::current_or_null() != NULL, "no current thread"); \ 364 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \ 365 } while (0) 366 367 #ifdef ASSERT 368 #define assert_used_and_recalculate_used_equal(g1h) \ 369 do { \ 370 size_t cur_used_bytes = g1h->used(); \ 371 size_t recal_used_bytes = g1h->recalculate_used(); \ 372 assert(cur_used_bytes == recal_used_bytes, "Used(" SIZE_FORMAT ") is not" \ 373 " same as recalculated used(" SIZE_FORMAT ").", \ 374 cur_used_bytes, recal_used_bytes); \ 375 } while (0) 376 #else 377 #define assert_used_and_recalculate_used_equal(g1h) do {} while(0) 378 #endif 379 380 // The young region list. 381 G1EdenRegions _eden; 382 G1SurvivorRegions _survivor; 383 384 STWGCTimer* _gc_timer_stw; 385 386 G1NewTracer* _gc_tracer_stw; 387 388 // The current policy object for the collector. 389 G1Policy* _policy; 390 G1HeapSizingPolicy* _heap_sizing_policy; 391 392 G1CollectionSet _collection_set; 393 394 // Try to allocate a single non-humongous HeapRegion sufficient for 395 // an allocation of the given word_size. If do_expand is true, 396 // attempt to expand the heap if necessary to satisfy the allocation 397 // request. 'type' takes the type of region to be allocated. (Use constants 398 // Old, Eden, Humongous, Survivor defined in HeapRegionType.) 399 HeapRegion* new_region(size_t word_size, 400 HeapRegionType type, 401 bool do_expand, 402 uint node_index = G1NUMA::AnyNodeIndex); 403 404 // Initialize a contiguous set of free regions of length num_regions 405 // and starting at index first so that they appear as a single 406 // humongous region. 407 HeapWord* humongous_obj_allocate_initialize_regions(HeapRegion* first_hr, 408 uint num_regions, 409 size_t word_size); 410 411 // Attempt to allocate a humongous object of the given size. Return 412 // NULL if unsuccessful. 413 HeapWord* humongous_obj_allocate(size_t word_size); 414 415 // The following two methods, allocate_new_tlab() and 416 // mem_allocate(), are the two main entry points from the runtime 417 // into the G1's allocation routines. They have the following 418 // assumptions: 419 // 420 // * They should both be called outside safepoints. 421 // 422 // * They should both be called without holding the Heap_lock. 423 // 424 // * All allocation requests for new TLABs should go to 425 // allocate_new_tlab(). 426 // 427 // * All non-TLAB allocation requests should go to mem_allocate(). 428 // 429 // * If either call cannot satisfy the allocation request using the 430 // current allocating region, they will try to get a new one. If 431 // this fails, they will attempt to do an evacuation pause and 432 // retry the allocation. 433 // 434 // * If all allocation attempts fail, even after trying to schedule 435 // an evacuation pause, allocate_new_tlab() will return NULL, 436 // whereas mem_allocate() will attempt a heap expansion and/or 437 // schedule a Full GC. 438 // 439 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 440 // should never be called with word_size being humongous. All 441 // humongous allocation requests should go to mem_allocate() which 442 // will satisfy them with a special path. 443 444 HeapWord* allocate_new_tlab(size_t min_size, 445 size_t requested_size, 446 size_t* actual_size) override; 447 448 HeapWord* mem_allocate(size_t word_size, 449 bool* gc_overhead_limit_was_exceeded) override; 450 451 // First-level mutator allocation attempt: try to allocate out of 452 // the mutator alloc region without taking the Heap_lock. This 453 // should only be used for non-humongous allocations. 454 inline HeapWord* attempt_allocation(size_t min_word_size, 455 size_t desired_word_size, 456 size_t* actual_word_size); 457 458 // Second-level mutator allocation attempt: take the Heap_lock and 459 // retry the allocation attempt, potentially scheduling a GC 460 // pause. This should only be used for non-humongous allocations. 461 HeapWord* attempt_allocation_slow(size_t word_size); 462 463 // Takes the Heap_lock and attempts a humongous allocation. It can 464 // potentially schedule a GC pause. 465 HeapWord* attempt_allocation_humongous(size_t word_size); 466 467 // Allocation attempt that should be called during safepoints (e.g., 468 // at the end of a successful GC). expect_null_mutator_alloc_region 469 // specifies whether the mutator alloc region is expected to be NULL 470 // or not. 471 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 472 bool expect_null_mutator_alloc_region); 473 474 // These methods are the "callbacks" from the G1AllocRegion class. 475 476 // For mutator alloc regions. 477 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force, uint node_index); 478 void retire_mutator_alloc_region(HeapRegion* alloc_region, 479 size_t allocated_bytes); 480 481 // For GC alloc regions. 482 bool has_more_regions(G1HeapRegionAttr dest); 483 HeapRegion* new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index); 484 void retire_gc_alloc_region(HeapRegion* alloc_region, 485 size_t allocated_bytes, G1HeapRegionAttr dest); 486 487 // - if explicit_gc is true, the GC is for a System.gc() etc, 488 // otherwise it's for a failed allocation. 489 // - if clear_all_soft_refs is true, all soft references should be 490 // cleared during the GC. 491 // - if do_maximal_compaction is true, full gc will do a maximally 492 // compacting collection, leaving no dead wood. 493 // - it returns false if it is unable to do the collection due to the 494 // GC locker being active, true otherwise. 495 bool do_full_collection(bool explicit_gc, 496 bool clear_all_soft_refs, 497 bool do_maximal_compaction); 498 499 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 500 void do_full_collection(bool clear_all_soft_refs) override; 501 502 // Helper to do a full collection that clears soft references. 503 bool upgrade_to_full_collection(); 504 505 // Callback from VM_G1CollectForAllocation operation. 506 // This function does everything necessary/possible to satisfy a 507 // failed allocation request (including collection, expansion, etc.) 508 HeapWord* satisfy_failed_allocation(size_t word_size, 509 bool* succeeded); 510 // Internal helpers used during full GC to split it up to 511 // increase readability. 512 bool abort_concurrent_cycle(); 513 void verify_before_full_collection(bool explicit_gc); 514 void prepare_heap_for_full_collection(); 515 void prepare_for_mutator_after_full_collection(); 516 void abort_refinement(); 517 void verify_after_full_collection(); 518 void print_heap_after_full_collection(); 519 520 // Helper method for satisfy_failed_allocation() 521 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 522 bool do_gc, 523 bool maximal_compaction, 524 bool expect_null_mutator_alloc_region, 525 bool* gc_succeeded); 526 527 // Attempting to expand the heap sufficiently 528 // to support an allocation of the given "word_size". If 529 // successful, perform the allocation and return the address of the 530 // allocated block, or else "NULL". 531 HeapWord* expand_and_allocate(size_t word_size); 532 533 void verify_numa_regions(const char* desc); 534 535 public: 536 // If during a concurrent start pause we may install a pending list head which is not 537 // otherwise reachable, ensure that it is marked in the bitmap for concurrent marking 538 // to discover. 539 void make_pending_list_reachable(); 540 541 G1ServiceThread* service_thread() const { return _service_thread; } 542 543 WorkerThreads* workers() const { return _workers; } 544 545 // Run the given batch task using the workers. 546 void run_batch_task(G1BatchedTask* cl); 547 548 // Return "optimal" number of chunks per region we want to use for claiming areas 549 // within a region to claim. 550 // The returned value is a trade-off between granularity of work distribution and 551 // memory usage and maintenance costs of that table. 552 // Testing showed that 64 for 1M/2M region, 128 for 4M/8M regions, 256 for 16/32M regions, 553 // and so on seems to be such a good trade-off. 554 static uint get_chunks_per_region(); 555 556 G1Allocator* allocator() { 557 return _allocator; 558 } 559 560 G1YoungGCEvacFailureInjector* evac_failure_injector() { return &_evac_failure_injector; } 561 562 G1HeapVerifier* verifier() { 563 return _verifier; 564 } 565 566 G1MonitoringSupport* monitoring_support() { 567 assert(_monitoring_support != nullptr, "should have been initialized"); 568 return _monitoring_support; 569 } 570 571 void resize_heap_if_necessary(); 572 573 // Check if there is memory to uncommit and if so schedule a task to do it. 574 void uncommit_regions_if_necessary(); 575 // Immediately uncommit uncommittable regions. 576 uint uncommit_regions(uint region_limit); 577 bool has_uncommittable_regions(); 578 579 G1NUMA* numa() const { return _numa; } 580 581 // Expand the garbage-first heap by at least the given size (in bytes!). 582 // Returns true if the heap was expanded by the requested amount; 583 // false otherwise. 584 // (Rounds up to a HeapRegion boundary.) 585 bool expand(size_t expand_bytes, WorkerThreads* pretouch_workers = NULL, double* expand_time_ms = NULL); 586 bool expand_single_region(uint node_index); 587 588 // Returns the PLAB statistics for a given destination. 589 inline G1EvacStats* alloc_buffer_stats(G1HeapRegionAttr dest); 590 591 // Determines PLAB size for a given destination. 592 inline size_t desired_plab_sz(G1HeapRegionAttr dest); 593 // Clamp the given PLAB word size to allowed values. Prevents humongous PLAB sizes 594 // for two reasons: 595 // * PLABs are allocated using a similar paths as oops, but should 596 // never be in a humongous region 597 // * Allowing humongous PLABs needlessly churns the region free lists 598 inline size_t clamp_plab_size(size_t value) const; 599 600 // Do anything common to GC's. 601 void gc_prologue(bool full); 602 void gc_epilogue(bool full); 603 604 // Does the given region fulfill remembered set based eager reclaim candidate requirements? 605 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const; 606 607 inline bool is_humongous_reclaim_candidate(uint region); 608 609 // Remove from the reclaim candidate set. Also remove from the 610 // collection set so that later encounters avoid the slow path. 611 inline void set_humongous_is_live(oop obj); 612 613 // Register the given region to be part of the collection set. 614 inline void register_humongous_candidate_region_with_region_attr(uint index); 615 616 // We register a region with the fast "in collection set" test. We 617 // simply set to true the array slot corresponding to this region. 618 void register_young_region_with_region_attr(HeapRegion* r) { 619 _region_attr.set_in_young(r->hrm_index()); 620 } 621 inline void register_new_survivor_region_with_region_attr(HeapRegion* r); 622 inline void register_region_with_region_attr(HeapRegion* r); 623 inline void register_old_region_with_region_attr(HeapRegion* r); 624 inline void register_optional_region_with_region_attr(HeapRegion* r); 625 626 void clear_region_attr(const HeapRegion* hr) { 627 _region_attr.clear(hr); 628 } 629 630 void clear_region_attr() { 631 _region_attr.clear(); 632 } 633 634 // Verify that the G1RegionAttr remset tracking corresponds to actual remset tracking 635 // for all regions. 636 void verify_region_attr_remset_is_tracked() PRODUCT_RETURN; 637 638 void clear_bitmap_for_region(HeapRegion* hr); 639 640 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 641 642 // This is called at the start of either a concurrent cycle or a Full 643 // GC to update the number of old marking cycles started. 644 void increment_old_marking_cycles_started(); 645 646 // This is called at the end of either a concurrent cycle or a Full 647 // GC to update the number of old marking cycles completed. Those two 648 // can happen in a nested fashion, i.e., we start a concurrent 649 // cycle, a Full GC happens half-way through it which ends first, 650 // and then the cycle notices that a Full GC happened and ends 651 // too. The concurrent parameter is a boolean to help us do a bit 652 // tighter consistency checking in the method. If concurrent is 653 // false, the caller is the inner caller in the nesting (i.e., the 654 // Full GC). If concurrent is true, the caller is the outer caller 655 // in this nesting (i.e., the concurrent cycle). Further nesting is 656 // not currently supported. The end of this call also notifies 657 // the G1OldGCCount_lock in case a Java thread is waiting for a full 658 // GC to happen (e.g., it called System.gc() with 659 // +ExplicitGCInvokesConcurrent). 660 // whole_heap_examined should indicate that during that old marking 661 // cycle the whole heap has been examined for live objects (as opposed 662 // to only parts, or aborted before completion). 663 void increment_old_marking_cycles_completed(bool concurrent, bool whole_heap_examined); 664 665 uint old_marking_cycles_started() const { 666 return _old_marking_cycles_started; 667 } 668 669 uint old_marking_cycles_completed() const { 670 return _old_marking_cycles_completed; 671 } 672 673 G1HRPrinter* hr_printer() { return &_hr_printer; } 674 675 // Allocates a new heap region instance. 676 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 677 678 // Allocate the highest free region in the reserved heap. This will commit 679 // regions as necessary. 680 HeapRegion* alloc_highest_free_region(); 681 682 // Frees a region by resetting its metadata and adding it to the free list 683 // passed as a parameter (this is usually a local list which will be appended 684 // to the master free list later or NULL if free list management is handled 685 // in another way). 686 // Callers must ensure they are the only one calling free on the given region 687 // at the same time. 688 void free_region(HeapRegion* hr, FreeRegionList* free_list); 689 690 // It dirties the cards that cover the block so that the post 691 // write barrier never queues anything when updating objects on this 692 // block. It is assumed (and in fact we assert) that the block 693 // belongs to a young region. 694 inline void dirty_young_block(HeapWord* start, size_t word_size); 695 696 // Frees a humongous region by collapsing it into individual regions 697 // and calling free_region() for each of them. The freed regions 698 // will be added to the free list that's passed as a parameter (this 699 // is usually a local list which will be appended to the master free 700 // list later). 701 // The method assumes that only a single thread is ever calling 702 // this for a particular region at once. 703 void free_humongous_region(HeapRegion* hr, 704 FreeRegionList* free_list); 705 706 // Facility for allocating a fixed range within the heap and marking 707 // the containing regions as 'archive'. For use at JVM init time, when the 708 // caller may mmap archived heap data at the specified range(s). 709 // Verify that the MemRegions specified in the argument array are within the 710 // reserved heap. 711 bool check_archive_addresses(MemRegion* range, size_t count); 712 713 // Commit the appropriate G1 regions containing the specified MemRegions 714 // and mark them as 'archive' regions. The regions in the array must be 715 // non-overlapping and in order of ascending address. 716 bool alloc_archive_regions(MemRegion* range, size_t count, bool open); 717 718 // Insert any required filler objects in the G1 regions around the specified 719 // ranges to make the regions parseable. This must be called after 720 // alloc_archive_regions, and after class loading has occurred. 721 void fill_archive_regions(MemRegion* range, size_t count); 722 723 // Populate the G1BlockOffsetTablePart for archived regions with the given 724 // memory ranges. 725 void populate_archive_regions_bot_part(MemRegion* range, size_t count); 726 727 // For each of the specified MemRegions, uncommit the containing G1 regions 728 // which had been allocated by alloc_archive_regions. This should be called 729 // rather than fill_archive_regions at JVM init time if the archive file 730 // mapping failed, with the same non-overlapping and sorted MemRegion array. 731 void dealloc_archive_regions(MemRegion* range, size_t count); 732 733 private: 734 735 // Shrink the garbage-first heap by at most the given size (in bytes!). 736 // (Rounds down to a HeapRegion boundary.) 737 void shrink(size_t shrink_bytes); 738 void shrink_helper(size_t expand_bytes); 739 740 // Schedule the VM operation that will do an evacuation pause to 741 // satisfy an allocation request of word_size. *succeeded will 742 // return whether the VM operation was successful (it did do an 743 // evacuation pause) or not (another thread beat us to it or the GC 744 // locker was active). Given that we should not be holding the 745 // Heap_lock when we enter this method, we will pass the 746 // gc_count_before (i.e., total_collections()) as a parameter since 747 // it has to be read while holding the Heap_lock. Currently, both 748 // methods that call do_collection_pause() release the Heap_lock 749 // before the call, so it's easy to read gc_count_before just before. 750 HeapWord* do_collection_pause(size_t word_size, 751 uint gc_count_before, 752 bool* succeeded, 753 GCCause::Cause gc_cause); 754 755 // Perform an incremental collection at a safepoint, possibly 756 // followed by a by-policy upgrade to a full collection. Returns 757 // false if unable to do the collection due to the GC locker being 758 // active, true otherwise. 759 // precondition: at safepoint on VM thread 760 // precondition: !is_gc_active() 761 bool do_collection_pause_at_safepoint(); 762 763 // Helper for do_collection_pause_at_safepoint, containing the guts 764 // of the incremental collection pause, executed by the vm thread. 765 void do_collection_pause_at_safepoint_helper(); 766 767 G1HeapVerifier::G1VerifyType young_collection_verify_type() const; 768 void verify_before_young_collection(G1HeapVerifier::G1VerifyType type); 769 void verify_after_young_collection(G1HeapVerifier::G1VerifyType type); 770 771 public: 772 // Start a concurrent cycle. 773 void start_concurrent_cycle(bool concurrent_operation_is_full_mark); 774 775 void prepare_for_mutator_after_young_collection(); 776 777 void retire_tlabs(); 778 779 void expand_heap_after_young_collection(); 780 // Update object copying statistics. 781 void record_obj_copy_mem_stats(); 782 783 private: 784 // The g1 remembered set of the heap. 785 G1RemSet* _rem_set; 786 // Global card set configuration 787 G1CardSetConfiguration _card_set_config; 788 789 G1MonotonicArenaFreePool _card_set_freelist_pool; 790 791 public: 792 // After a collection pause, reset eden and the collection set. 793 void clear_eden(); 794 void clear_collection_set(); 795 796 // Abandon the current collection set without recording policy 797 // statistics or updating free lists. 798 void abandon_collection_set(G1CollectionSet* collection_set); 799 800 // The concurrent marker (and the thread it runs in.) 801 G1ConcurrentMark* _cm; 802 G1ConcurrentMarkThread* _cm_thread; 803 804 // The concurrent refiner. 805 G1ConcurrentRefine* _cr; 806 807 // The parallel task queues 808 G1ScannerTasksQueueSet *_task_queues; 809 810 // ("Weak") Reference processing support. 811 // 812 // G1 has 2 instances of the reference processor class. 813 // 814 // One (_ref_processor_cm) handles reference object discovery and subsequent 815 // processing during concurrent marking cycles. Discovery is enabled/disabled 816 // at the start/end of a concurrent marking cycle. 817 // 818 // The other (_ref_processor_stw) handles reference object discovery and 819 // processing during incremental evacuation pauses and full GC pauses. 820 // 821 // ## Incremental evacuation pauses 822 // 823 // STW ref processor discovery is enabled/disabled at the start/end of an 824 // incremental evacuation pause. No particular handling of the CM ref 825 // processor is needed, apart from treating the discovered references as 826 // roots; CM discovery does not need to be temporarily disabled as all 827 // marking threads are paused during incremental evacuation pauses. 828 // 829 // ## Full GC pauses 830 // 831 // We abort any ongoing concurrent marking cycle, disable CM discovery, and 832 // temporarily substitute a new closure for the STW ref processor's 833 // _is_alive_non_header field (old value is restored after the full GC). Then 834 // STW ref processor discovery is enabled, and marking & compaction 835 // commences. 836 837 // The (stw) reference processor... 838 ReferenceProcessor* _ref_processor_stw; 839 840 // During reference object discovery, the _is_alive_non_header 841 // closure (if non-null) is applied to the referent object to 842 // determine whether the referent is live. If so then the 843 // reference object does not need to be 'discovered' and can 844 // be treated as a regular oop. This has the benefit of reducing 845 // the number of 'discovered' reference objects that need to 846 // be processed. 847 // 848 // Instance of the is_alive closure for embedding into the 849 // STW reference processor as the _is_alive_non_header field. 850 // Supplying a value for the _is_alive_non_header field is 851 // optional but doing so prevents unnecessary additions to 852 // the discovered lists during reference discovery. 853 G1STWIsAliveClosure _is_alive_closure_stw; 854 855 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw; 856 857 // The (concurrent marking) reference processor... 858 ReferenceProcessor* _ref_processor_cm; 859 860 // Instance of the concurrent mark is_alive closure for embedding 861 // into the Concurrent Marking reference processor as the 862 // _is_alive_non_header field. Supplying a value for the 863 // _is_alive_non_header field is optional but doing so prevents 864 // unnecessary additions to the discovered lists during reference 865 // discovery. 866 G1CMIsAliveClosure _is_alive_closure_cm; 867 868 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm; 869 public: 870 871 G1ScannerTasksQueueSet* task_queues() const; 872 G1ScannerTasksQueue* task_queue(uint i) const; 873 874 // Create a G1CollectedHeap. 875 // Must call the initialize method afterwards. 876 // May not return if something goes wrong. 877 G1CollectedHeap(); 878 879 private: 880 jint initialize_concurrent_refinement(); 881 jint initialize_service_thread(); 882 public: 883 // Initialize the G1CollectedHeap to have the initial and 884 // maximum sizes and remembered and barrier sets 885 // specified by the policy object. 886 jint initialize() override; 887 888 // Returns whether concurrent mark threads (and the VM) are about to terminate. 889 bool concurrent_mark_is_terminating() const; 890 891 void stop() override; 892 void safepoint_synchronize_begin() override; 893 void safepoint_synchronize_end() override; 894 895 // Does operations required after initialization has been done. 896 void post_initialize() override; 897 898 // Initialize weak reference processing. 899 void ref_processing_init(); 900 901 Name kind() const override { 902 return CollectedHeap::G1; 903 } 904 905 const char* name() const override { 906 return "G1"; 907 } 908 909 const G1CollectorState* collector_state() const { return &_collector_state; } 910 G1CollectorState* collector_state() { return &_collector_state; } 911 912 // The current policy object for the collector. 913 G1Policy* policy() const { return _policy; } 914 // The remembered set. 915 G1RemSet* rem_set() const { return _rem_set; } 916 917 const G1MonotonicArenaFreePool* card_set_freelist_pool() const { return &_card_set_freelist_pool; } 918 G1MonotonicArenaFreePool* card_set_freelist_pool() { return &_card_set_freelist_pool; } 919 920 inline G1GCPhaseTimes* phase_times() const; 921 922 const G1CollectionSet* collection_set() const { return &_collection_set; } 923 G1CollectionSet* collection_set() { return &_collection_set; } 924 925 SoftRefPolicy* soft_ref_policy() override; 926 927 void initialize_serviceability() override; 928 MemoryUsage memory_usage() override; 929 GrowableArray<GCMemoryManager*> memory_managers() override; 930 GrowableArray<MemoryPool*> memory_pools() override; 931 932 void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) override; 933 934 static void start_codecache_marking_cycle_if_inactive(bool concurrent_mark_start); 935 static void finish_codecache_marking_cycle(); 936 937 // The shared block offset table array. 938 G1BlockOffsetTable* bot() const { return _bot; } 939 940 // Reference Processing accessors 941 942 // The STW reference processor.... 943 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 944 945 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 946 STWGCTimer* gc_timer_stw() const { return _gc_timer_stw; } 947 948 // The Concurrent Marking reference processor... 949 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 950 951 size_t unused_committed_regions_in_bytes() const; 952 953 size_t capacity() const override; 954 size_t used() const override; 955 // This should be called when we're not holding the heap lock. The 956 // result might be a bit inaccurate. 957 size_t used_unlocked() const; 958 size_t recalculate_used() const; 959 960 // These virtual functions do the actual allocation. 961 // Some heaps may offer a contiguous region for shared non-blocking 962 // allocation, via inlined code (by exporting the address of the top and 963 // end fields defining the extent of the contiguous allocation region.) 964 // But G1CollectedHeap doesn't yet support this. 965 966 bool is_maximal_no_gc() const override { 967 return _hrm.available() == 0; 968 } 969 970 // Returns true if an incremental GC should be upgrade to a full gc. This 971 // is done when there are no free regions and the heap can't be expanded. 972 bool should_upgrade_to_full_gc() const { 973 return is_maximal_no_gc() && num_free_regions() == 0; 974 } 975 976 // The current number of regions in the heap. 977 uint num_regions() const { return _hrm.length(); } 978 979 // The max number of regions reserved for the heap. Except for static array 980 // sizing purposes you probably want to use max_regions(). 981 uint max_reserved_regions() const { return _hrm.reserved_length(); } 982 983 // Max number of regions that can be committed. 984 uint max_regions() const { return _hrm.max_length(); } 985 986 // The number of regions that are completely free. 987 uint num_free_regions() const { return _hrm.num_free_regions(); } 988 989 // The number of regions that can be allocated into. 990 uint num_free_or_available_regions() const { return num_free_regions() + _hrm.available(); } 991 992 MemoryUsage get_auxiliary_data_memory_usage() const { 993 return _hrm.get_auxiliary_data_memory_usage(); 994 } 995 996 // The number of regions that are not completely free. 997 uint num_used_regions() const { return num_regions() - num_free_regions(); } 998 999 #ifdef ASSERT 1000 bool is_on_master_free_list(HeapRegion* hr) { 1001 return _hrm.is_free(hr); 1002 } 1003 #endif // ASSERT 1004 1005 inline void old_set_add(HeapRegion* hr); 1006 inline void old_set_remove(HeapRegion* hr); 1007 1008 inline void archive_set_add(HeapRegion* hr); 1009 1010 size_t non_young_capacity_bytes() { 1011 return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes; 1012 } 1013 1014 // Determine whether the given region is one that we are using as an 1015 // old GC alloc region. 1016 bool is_old_gc_alloc_region(HeapRegion* hr); 1017 1018 // Perform a collection of the heap; intended for use in implementing 1019 // "System.gc". This probably implies as full a collection as the 1020 // "CollectedHeap" supports. 1021 void collect(GCCause::Cause cause) override; 1022 1023 // Perform a collection of the heap with the given cause. 1024 // Returns whether this collection actually executed. 1025 bool try_collect(GCCause::Cause cause, const G1GCCounters& counters_before); 1026 1027 void start_concurrent_gc_for_metadata_allocation(GCCause::Cause gc_cause); 1028 1029 void remove_from_old_gen_sets(const uint old_regions_removed, 1030 const uint archive_regions_removed, 1031 const uint humongous_regions_removed); 1032 void prepend_to_freelist(FreeRegionList* list); 1033 void decrement_summary_bytes(size_t bytes); 1034 1035 bool is_in(const void* p) const override; 1036 1037 // Return "TRUE" iff the given object address is within the collection 1038 // set. Assumes that the reference points into the heap. 1039 inline bool is_in_cset(const HeapRegion *hr) const; 1040 inline bool is_in_cset(oop obj) const; 1041 inline bool is_in_cset(HeapWord* addr) const; 1042 1043 inline bool is_in_cset_or_humongous_candidate(const oop obj); 1044 1045 private: 1046 // This array is used for a quick test on whether a reference points into 1047 // the collection set or not. Each of the array's elements denotes whether the 1048 // corresponding region is in the collection set or not. 1049 G1HeapRegionAttrBiasedMappedArray _region_attr; 1050 1051 public: 1052 1053 inline G1HeapRegionAttr region_attr(const void* obj) const; 1054 inline G1HeapRegionAttr region_attr(uint idx) const; 1055 1056 MemRegion reserved() const { 1057 return _hrm.reserved(); 1058 } 1059 1060 bool is_in_reserved(const void* addr) const { 1061 return reserved().contains(addr); 1062 } 1063 1064 G1CardTable* card_table() const { 1065 return _card_table; 1066 } 1067 1068 // Iteration functions. 1069 1070 void object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer); 1071 1072 // Iterate over all objects, calling "cl.do_object" on each. 1073 void object_iterate(ObjectClosure* cl) override; 1074 1075 ParallelObjectIteratorImpl* parallel_object_iterator(uint thread_num) override; 1076 1077 // Keep alive an object that was loaded with AS_NO_KEEPALIVE. 1078 void keep_alive(oop obj) override; 1079 1080 // Iterate over heap regions, in address order, terminating the 1081 // iteration early if the "do_heap_region" method returns "true". 1082 void heap_region_iterate(HeapRegionClosure* blk) const; 1083 void heap_region_iterate(HeapRegionIndexClosure* blk) const; 1084 1085 // Return the region with the given index. It assumes the index is valid. 1086 inline HeapRegion* region_at(uint index) const; 1087 inline HeapRegion* region_at_or_null(uint index) const; 1088 1089 // Return the next region (by index) that is part of the same 1090 // humongous object that hr is part of. 1091 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1092 1093 // Calculate the region index of the given address. Given address must be 1094 // within the heap. 1095 inline uint addr_to_region(const void* addr) const; 1096 1097 inline HeapWord* bottom_addr_for_region(uint index) const; 1098 1099 // Two functions to iterate over the heap regions in parallel. Threads 1100 // compete using the HeapRegionClaimer to claim the regions before 1101 // applying the closure on them. 1102 // The _from_worker_offset version uses the HeapRegionClaimer and 1103 // the worker id to calculate a start offset to prevent all workers to 1104 // start from the point. 1105 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 1106 HeapRegionClaimer* hrclaimer, 1107 uint worker_id) const; 1108 1109 void heap_region_par_iterate_from_start(HeapRegionClosure* cl, 1110 HeapRegionClaimer* hrclaimer) const; 1111 1112 // Iterate over all regions in the collection set in parallel. 1113 void collection_set_par_iterate_all(HeapRegionClosure* cl, 1114 HeapRegionClaimer* hr_claimer, 1115 uint worker_id); 1116 1117 // Iterate over all regions currently in the current collection set. 1118 void collection_set_iterate_all(HeapRegionClosure* blk); 1119 1120 // Iterate over the regions in the current increment of the collection set. 1121 // Starts the iteration so that the start regions of a given worker id over the 1122 // set active_workers are evenly spread across the set of collection set regions 1123 // to be iterated. 1124 // The variant with the HeapRegionClaimer guarantees that the closure will be 1125 // applied to a particular region exactly once. 1126 void collection_set_iterate_increment_from(HeapRegionClosure *blk, uint worker_id) { 1127 collection_set_iterate_increment_from(blk, NULL, worker_id); 1128 } 1129 void collection_set_iterate_increment_from(HeapRegionClosure *blk, HeapRegionClaimer* hr_claimer, uint worker_id); 1130 // Iterate over the array of region indexes, uint regions[length], applying 1131 // the given HeapRegionClosure on each region. The worker_id will determine where 1132 // to start the iteration to allow for more efficient parallel iteration. 1133 void par_iterate_regions_array(HeapRegionClosure* cl, 1134 HeapRegionClaimer* hr_claimer, 1135 const uint regions[], 1136 size_t length, 1137 uint worker_id) const; 1138 1139 // Returns the HeapRegion that contains addr. addr must not be nullptr. 1140 inline HeapRegion* heap_region_containing(const void* addr) const; 1141 1142 // Returns the HeapRegion that contains addr, or nullptr if that is an uncommitted 1143 // region. addr must not be nullptr. 1144 inline HeapRegion* heap_region_containing_or_null(const void* addr) const; 1145 1146 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1147 // each address in the (reserved) heap is a member of exactly 1148 // one block. The defining characteristic of a block is that it is 1149 // possible to find its size, and thus to progress forward to the next 1150 // block. (Blocks may be of different sizes.) Thus, blocks may 1151 // represent Java objects, or they might be free blocks in a 1152 // free-list-based heap (or subheap), as long as the two kinds are 1153 // distinguishable and the size of each is determinable. 1154 1155 // Returns the address of the start of the "block" that contains the 1156 // address "addr". We say "blocks" instead of "object" since some heaps 1157 // may not pack objects densely; a chunk may either be an object or a 1158 // non-object. 1159 HeapWord* block_start(const void* addr) const; 1160 1161 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1162 // the block is an object. 1163 bool block_is_obj(const HeapWord* addr) const; 1164 1165 // Section on thread-local allocation buffers (TLABs) 1166 // See CollectedHeap for semantics. 1167 1168 size_t tlab_capacity(Thread* ignored) const override; 1169 size_t tlab_used(Thread* ignored) const override; 1170 size_t max_tlab_size() const override; 1171 size_t unsafe_max_tlab_alloc(Thread* ignored) const override; 1172 1173 inline bool is_in_young(const oop obj) const; 1174 inline bool requires_barriers(stackChunkOop obj) const override; 1175 1176 // Returns "true" iff the given word_size is "very large". 1177 static bool is_humongous(size_t word_size) { 1178 // Note this has to be strictly greater-than as the TLABs 1179 // are capped at the humongous threshold and we want to 1180 // ensure that we don't try to allocate a TLAB as 1181 // humongous and that we don't allocate a humongous 1182 // object in a TLAB. 1183 return word_size > _humongous_object_threshold_in_words; 1184 } 1185 1186 // Returns the humongous threshold for a specific region size 1187 static size_t humongous_threshold_for(size_t region_size) { 1188 return (region_size / 2); 1189 } 1190 1191 // Returns the number of regions the humongous object of the given word size 1192 // requires. 1193 static size_t humongous_obj_size_in_regions(size_t word_size); 1194 1195 // Print the maximum heap capacity. 1196 size_t max_capacity() const override; 1197 1198 Tickspan time_since_last_collection() const { return Ticks::now() - _collection_pause_end; } 1199 1200 // Convenience function to be used in situations where the heap type can be 1201 // asserted to be this type. 1202 static G1CollectedHeap* heap() { 1203 return named_heap<G1CollectedHeap>(CollectedHeap::G1); 1204 } 1205 1206 void set_region_short_lived_locked(HeapRegion* hr); 1207 // add appropriate methods for any other surv rate groups 1208 1209 G1SurvivorRegions* survivor() { return &_survivor; } 1210 1211 uint eden_regions_count() const { return _eden.length(); } 1212 uint eden_regions_count(uint node_index) const { return _eden.regions_on_node(node_index); } 1213 uint survivor_regions_count() const { return _survivor.length(); } 1214 uint survivor_regions_count(uint node_index) const { return _survivor.regions_on_node(node_index); } 1215 size_t eden_regions_used_bytes() const { return _eden.used_bytes(); } 1216 size_t survivor_regions_used_bytes() const { return _survivor.used_bytes(); } 1217 uint young_regions_count() const { return _eden.length() + _survivor.length(); } 1218 uint old_regions_count() const { return _old_set.length(); } 1219 uint archive_regions_count() const { return _archive_set.length(); } 1220 uint humongous_regions_count() const { return _humongous_set.length(); } 1221 1222 #ifdef ASSERT 1223 bool check_young_list_empty(); 1224 #endif 1225 1226 bool is_marked(oop obj) const; 1227 1228 inline static bool is_obj_filler(const oop obj); 1229 // Determine if an object is dead, given the object and also 1230 // the region to which the object belongs. 1231 inline bool is_obj_dead(const oop obj, const HeapRegion* hr) const; 1232 1233 // Determine if an object is dead, given only the object itself. 1234 // This will find the region to which the object belongs and 1235 // then call the region version of the same function. 1236 // If obj is NULL it is not dead. 1237 inline bool is_obj_dead(const oop obj) const; 1238 1239 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const; 1240 inline bool is_obj_dead_full(const oop obj) const; 1241 1242 // Mark the live object that failed evacuation in the bitmap. 1243 void mark_evac_failure_object(uint worker_id, oop obj, size_t obj_size) const; 1244 1245 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1246 1247 // Refinement 1248 1249 G1ConcurrentRefine* concurrent_refine() const { return _cr; } 1250 1251 // Optimized nmethod scanning support routines 1252 1253 // Register the given nmethod with the G1 heap. 1254 void register_nmethod(nmethod* nm) override; 1255 1256 // Unregister the given nmethod from the G1 heap. 1257 void unregister_nmethod(nmethod* nm) override; 1258 1259 // No nmethod verification implemented. 1260 void verify_nmethod(nmethod* nm) override {} 1261 1262 // Recalculate amount of used memory after GC. Must be called after all allocation 1263 // has finished. 1264 void update_used_after_gc(bool evacuation_failed); 1265 1266 // Rebuild the code root lists for each region 1267 // after a full GC. 1268 void rebuild_code_roots(); 1269 1270 // Performs cleaning of data structures after class unloading. 1271 void complete_cleaning(bool class_unloading_occurred); 1272 1273 // Verification 1274 1275 // Perform any cleanup actions necessary before allowing a verification. 1276 void prepare_for_verify() override; 1277 1278 // Perform verification. 1279 void verify(VerifyOption vo) override; 1280 1281 // WhiteBox testing support. 1282 bool supports_concurrent_gc_breakpoints() const override; 1283 1284 WorkerThreads* safepoint_workers() override { return _workers; } 1285 1286 bool is_archived_object(oop object) const override; 1287 1288 // The methods below are here for convenience and dispatch the 1289 // appropriate method depending on value of the given VerifyOption 1290 // parameter. The values for that parameter, and their meanings, 1291 // are the same as those above. 1292 1293 bool is_obj_dead_cond(const oop obj, 1294 const HeapRegion* hr, 1295 const VerifyOption vo) const; 1296 1297 bool is_obj_dead_cond(const oop obj, 1298 const VerifyOption vo) const; 1299 1300 G1HeapSummary create_g1_heap_summary(); 1301 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1302 1303 void pin_object(JavaThread* thread, oop obj) override; 1304 void unpin_object(JavaThread* thread, oop obj) override; 1305 1306 // Printing 1307 private: 1308 void print_heap_regions() const; 1309 void print_regions_on(outputStream* st) const; 1310 1311 public: 1312 void print_on(outputStream* st) const override; 1313 void print_extended_on(outputStream* st) const override; 1314 void print_on_error(outputStream* st) const override; 1315 1316 void gc_threads_do(ThreadClosure* tc) const override; 1317 1318 // Override 1319 void print_tracing_info() const override; 1320 1321 // Used to print information about locations in the hs_err file. 1322 bool print_location(outputStream* st, void* addr) const override; 1323 }; 1324 1325 // Scoped object that performs common pre- and post-gc heap printing operations. 1326 class G1HeapPrinterMark : public StackObj { 1327 G1CollectedHeap* _g1h; 1328 G1HeapTransition _heap_transition; 1329 1330 public: 1331 G1HeapPrinterMark(G1CollectedHeap* g1h); 1332 ~G1HeapPrinterMark(); 1333 }; 1334 1335 // Scoped object that performs common pre- and post-gc operations related to 1336 // JFR events. 1337 class G1JFRTracerMark : public StackObj { 1338 protected: 1339 STWGCTimer* _timer; 1340 GCTracer* _tracer; 1341 1342 public: 1343 G1JFRTracerMark(STWGCTimer* timer, GCTracer* tracer); 1344 ~G1JFRTracerMark(); 1345 }; 1346 1347 #endif // SHARE_GC_G1_G1COLLECTEDHEAP_HPP