1 /* 2 * Copyright (c) 2001, 2020, 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/g1CollectionSet.hpp" 32 #include "gc/g1/g1CollectorState.hpp" 33 #include "gc/g1/g1ConcurrentMark.hpp" 34 #include "gc/g1/g1EdenRegions.hpp" 35 #include "gc/g1/g1EvacFailure.hpp" 36 #include "gc/g1/g1EvacStats.hpp" 37 #include "gc/g1/g1EvacuationInfo.hpp" 38 #include "gc/g1/g1GCPhaseTimes.hpp" 39 #include "gc/g1/g1HeapTransition.hpp" 40 #include "gc/g1/g1HeapVerifier.hpp" 41 #include "gc/g1/g1HRPrinter.hpp" 42 #include "gc/g1/g1HeapRegionAttr.hpp" 43 #include "gc/g1/g1MonitoringSupport.hpp" 44 #include "gc/g1/g1NUMA.hpp" 45 #include "gc/g1/g1RedirtyCardsQueue.hpp" 46 #include "gc/g1/g1SurvivorRegions.hpp" 47 #include "gc/g1/g1YCTypes.hpp" 48 #include "gc/g1/heapRegionManager.hpp" 49 #include "gc/g1/heapRegionSet.hpp" 50 #include "gc/g1/heterogeneousHeapRegionManager.hpp" 51 #include "gc/shared/barrierSet.hpp" 52 #include "gc/shared/collectedHeap.hpp" 53 #include "gc/shared/gcHeapSummary.hpp" 54 #include "gc/shared/plab.hpp" 55 #include "gc/shared/preservedMarks.hpp" 56 #include "gc/shared/softRefPolicy.hpp" 57 #include "gc/shared/taskqueue.hpp" 58 #include "memory/memRegion.hpp" 59 #include "utilities/stack.hpp" 60 61 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 62 // It uses the "Garbage First" heap organization and algorithm, which 63 // may combine concurrent marking with parallel, incremental compaction of 64 // heap subsets that will yield large amounts of garbage. 65 66 // Forward declarations 67 class HeapRegion; 68 class GenerationSpec; 69 class G1ParScanThreadState; 70 class G1ParScanThreadStateSet; 71 class G1ParScanThreadState; 72 class MemoryPool; 73 class MemoryManager; 74 class ObjectClosure; 75 class SpaceClosure; 76 class CompactibleSpaceClosure; 77 class Space; 78 class G1CardTableEntryClosure; 79 class G1CollectionSet; 80 class G1Policy; 81 class G1HotCardCache; 82 class G1RemSet; 83 class G1YoungRemSetSamplingThread; 84 class G1ConcurrentMark; 85 class G1ConcurrentMarkThread; 86 class G1ConcurrentRefine; 87 class GenerationCounters; 88 class STWGCTimer; 89 class G1NewTracer; 90 class EvacuationFailedInfo; 91 class nmethod; 92 class WorkGang; 93 class G1Allocator; 94 class G1ArchiveAllocator; 95 class G1FullGCScope; 96 class G1HeapVerifier; 97 class G1HeapSizingPolicy; 98 class G1HeapSummary; 99 class G1EvacSummary; 100 101 typedef OverflowTaskQueue<ScannerTask, mtGC> G1ScannerTasksQueue; 102 typedef GenericTaskQueueSet<G1ScannerTasksQueue, mtGC> G1ScannerTasksQueueSet; 103 104 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 105 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 106 107 // The G1 STW is alive closure. 108 // An instance is embedded into the G1CH and used as the 109 // (optional) _is_alive_non_header closure in the STW 110 // reference processor. It is also extensively used during 111 // reference processing during STW evacuation pauses. 112 class G1STWIsAliveClosure : public BoolObjectClosure { 113 G1CollectedHeap* _g1h; 114 public: 115 G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {} 116 bool do_object_b(oop p); 117 }; 118 119 class G1STWSubjectToDiscoveryClosure : public BoolObjectClosure { 120 G1CollectedHeap* _g1h; 121 public: 122 G1STWSubjectToDiscoveryClosure(G1CollectedHeap* g1h) : _g1h(g1h) {} 123 bool do_object_b(oop p); 124 }; 125 126 class G1RegionMappingChangedListener : public G1MappingChangedListener { 127 private: 128 void reset_from_card_cache(uint start_idx, size_t num_regions); 129 public: 130 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 131 }; 132 133 class G1CollectedHeap : public CollectedHeap { 134 friend class VM_CollectForMetadataAllocation; 135 friend class VM_G1CollectForAllocation; 136 friend class VM_G1CollectFull; 137 friend class VM_G1TryInitiateConcMark; 138 friend class VMStructs; 139 friend class MutatorAllocRegion; 140 friend class G1FullCollector; 141 friend class G1GCAllocRegion; 142 friend class G1HeapVerifier; 143 144 // Closures used in implementation. 145 friend class G1ParScanThreadState; 146 friend class G1ParScanThreadStateSet; 147 friend class G1EvacuateRegionsTask; 148 friend class G1PLABAllocator; 149 150 // Other related classes. 151 friend class HeapRegionClaimer; 152 153 // Testing classes. 154 friend class G1CheckRegionAttrTableClosure; 155 156 private: 157 G1YoungRemSetSamplingThread* _young_gen_sampling_thread; 158 159 WorkGang* _workers; 160 G1CardTable* _card_table; 161 162 Ticks _collection_pause_end; 163 164 SoftRefPolicy _soft_ref_policy; 165 166 static size_t _humongous_object_threshold_in_words; 167 168 // These sets keep track of old, archive and humongous regions respectively. 169 HeapRegionSet _old_set; 170 HeapRegionSet _archive_set; 171 HeapRegionSet _humongous_set; 172 173 void eagerly_reclaim_humongous_regions(); 174 // Start a new incremental collection set for the next pause. 175 void start_new_collection_set(); 176 177 // The block offset table for the G1 heap. 178 G1BlockOffsetTable* _bot; 179 180 // Tears down the region sets / lists so that they are empty and the 181 // regions on the heap do not belong to a region set / list. The 182 // only exception is the humongous set which we leave unaltered. If 183 // free_list_only is true, it will only tear down the master free 184 // list. It is called before a Full GC (free_list_only == false) or 185 // before heap shrinking (free_list_only == true). 186 void tear_down_region_sets(bool free_list_only); 187 188 // Rebuilds the region sets / lists so that they are repopulated to 189 // reflect the contents of the heap. The only exception is the 190 // humongous set which was not torn down in the first place. If 191 // free_list_only is true, it will only rebuild the master free 192 // list. It is called after a Full GC (free_list_only == false) or 193 // after heap shrinking (free_list_only == true). 194 void rebuild_region_sets(bool free_list_only); 195 196 // Callback for region mapping changed events. 197 G1RegionMappingChangedListener _listener; 198 199 // Handle G1 NUMA support. 200 G1NUMA* _numa; 201 202 // The sequence of all heap regions in the heap. 203 HeapRegionManager* _hrm; 204 205 // Manages all allocations with regions except humongous object allocations. 206 G1Allocator* _allocator; 207 208 // Manages all heap verification. 209 G1HeapVerifier* _verifier; 210 211 // Outside of GC pauses, the number of bytes used in all regions other 212 // than the current allocation region(s). 213 volatile size_t _summary_bytes_used; 214 215 void increase_used(size_t bytes); 216 void decrease_used(size_t bytes); 217 218 void set_used(size_t bytes); 219 220 // Number of bytes used in all regions during GC. Typically changed when 221 // retiring a GC alloc region. 222 size_t _bytes_used_during_gc; 223 224 // Class that handles archive allocation ranges. 225 G1ArchiveAllocator* _archive_allocator; 226 227 // GC allocation statistics policy for survivors. 228 G1EvacStats _survivor_evac_stats; 229 230 // GC allocation statistics policy for tenured objects. 231 G1EvacStats _old_evac_stats; 232 233 // It specifies whether we should attempt to expand the heap after a 234 // region allocation failure. If heap expansion fails we set this to 235 // false so that we don't re-attempt the heap expansion (it's likely 236 // that subsequent expansion attempts will also fail if one fails). 237 // Currently, it is only consulted during GC and it's reset at the 238 // start of each GC. 239 bool _expand_heap_after_alloc_failure; 240 241 // Helper for monitoring and management support. 242 G1MonitoringSupport* _g1mm; 243 244 // Records whether the region at the given index is (still) a 245 // candidate for eager reclaim. Only valid for humongous start 246 // regions; other regions have unspecified values. Humongous start 247 // regions are initialized at start of collection pause, with 248 // candidates removed from the set as they are found reachable from 249 // roots or the young generation. 250 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 251 protected: 252 bool default_value() const { return false; } 253 public: 254 void clear() { G1BiasedMappedArray<bool>::clear(); } 255 void set_candidate(uint region, bool value) { 256 set_by_index(region, value); 257 } 258 bool is_candidate(uint region) { 259 return get_by_index(region); 260 } 261 }; 262 263 HumongousReclaimCandidates _humongous_reclaim_candidates; 264 // Stores whether during humongous object registration we found candidate regions. 265 // If not, we can skip a few steps. 266 bool _has_humongous_reclaim_candidates; 267 268 G1HRPrinter _hr_printer; 269 270 // Return true if an explicit GC should start a concurrent cycle instead 271 // of doing a STW full GC. A concurrent cycle should be started if: 272 // (a) cause == _g1_humongous_allocation, 273 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent, 274 // (c) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent, 275 // (d) cause == _wb_conc_mark or _wb_breakpoint, 276 // (e) cause == _g1_periodic_collection and +G1PeriodicGCInvokesConcurrent. 277 bool should_do_concurrent_full_gc(GCCause::Cause cause); 278 279 // Attempt to start a concurrent cycle with the indicated cause. 280 // precondition: should_do_concurrent_full_gc(cause) 281 bool try_collect_concurrently(GCCause::Cause cause, 282 uint gc_counter, 283 uint old_marking_started_before); 284 285 // Return true if should upgrade to full gc after an incremental one. 286 bool should_upgrade_to_full_gc(GCCause::Cause cause); 287 288 // indicates whether we are in young or mixed GC mode 289 G1CollectorState _collector_state; 290 291 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 292 // concurrent cycles) we have started. 293 volatile uint _old_marking_cycles_started; 294 295 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 296 // concurrent cycles) we have completed. 297 volatile uint _old_marking_cycles_completed; 298 299 // This is a non-product method that is helpful for testing. It is 300 // called at the end of a GC and artificially expands the heap by 301 // allocating a number of dead regions. This way we can induce very 302 // frequent marking cycles and stress the cleanup / concurrent 303 // cleanup code more (as all the regions that will be allocated by 304 // this method will be found dead by the marking cycle). 305 void allocate_dummy_regions() PRODUCT_RETURN; 306 307 // If the HR printer is active, dump the state of the regions in the 308 // heap after a compaction. 309 void print_hrm_post_compaction(); 310 311 // Create a memory mapper for auxiliary data structures of the given size and 312 // translation factor. 313 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 314 size_t size, 315 size_t translation_factor); 316 317 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 318 319 // These are macros so that, if the assert fires, we get the correct 320 // line number, file, etc. 321 322 #define heap_locking_asserts_params(_extra_message_) \ 323 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 324 (_extra_message_), \ 325 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 326 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 327 BOOL_TO_STR(Thread::current()->is_VM_thread()) 328 329 #define assert_heap_locked() \ 330 do { \ 331 assert(Heap_lock->owned_by_self(), \ 332 heap_locking_asserts_params("should be holding the Heap_lock")); \ 333 } while (0) 334 335 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 336 do { \ 337 assert(Heap_lock->owned_by_self() || \ 338 (SafepointSynchronize::is_at_safepoint() && \ 339 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 340 heap_locking_asserts_params("should be holding the Heap_lock or " \ 341 "should be at a safepoint")); \ 342 } while (0) 343 344 #define assert_heap_locked_and_not_at_safepoint() \ 345 do { \ 346 assert(Heap_lock->owned_by_self() && \ 347 !SafepointSynchronize::is_at_safepoint(), \ 348 heap_locking_asserts_params("should be holding the Heap_lock and " \ 349 "should not be at a safepoint")); \ 350 } while (0) 351 352 #define assert_heap_not_locked() \ 353 do { \ 354 assert(!Heap_lock->owned_by_self(), \ 355 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 356 } while (0) 357 358 #define assert_heap_not_locked_and_not_at_safepoint() \ 359 do { \ 360 assert(!Heap_lock->owned_by_self() && \ 361 !SafepointSynchronize::is_at_safepoint(), \ 362 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 363 "should not be at a safepoint")); \ 364 } while (0) 365 366 #define assert_at_safepoint_on_vm_thread() \ 367 do { \ 368 assert_at_safepoint(); \ 369 assert(Thread::current_or_null() != NULL, "no current thread"); \ 370 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \ 371 } while (0) 372 373 #ifdef ASSERT 374 #define assert_used_and_recalculate_used_equal(g1h) \ 375 do { \ 376 size_t cur_used_bytes = g1h->used(); \ 377 size_t recal_used_bytes = g1h->recalculate_used(); \ 378 assert(cur_used_bytes == recal_used_bytes, "Used(" SIZE_FORMAT ") is not" \ 379 " same as recalculated used(" SIZE_FORMAT ").", \ 380 cur_used_bytes, recal_used_bytes); \ 381 } while (0) 382 #else 383 #define assert_used_and_recalculate_used_equal(g1h) do {} while(0) 384 #endif 385 386 const char* young_gc_name() const; 387 388 // The young region list. 389 G1EdenRegions _eden; 390 G1SurvivorRegions _survivor; 391 392 STWGCTimer* _gc_timer_stw; 393 394 G1NewTracer* _gc_tracer_stw; 395 396 // The current policy object for the collector. 397 G1Policy* _policy; 398 G1HeapSizingPolicy* _heap_sizing_policy; 399 400 G1CollectionSet _collection_set; 401 402 // Try to allocate a single non-humongous HeapRegion sufficient for 403 // an allocation of the given word_size. If do_expand is true, 404 // attempt to expand the heap if necessary to satisfy the allocation 405 // request. 'type' takes the type of region to be allocated. (Use constants 406 // Old, Eden, Humongous, Survivor defined in HeapRegionType.) 407 HeapRegion* new_region(size_t word_size, 408 HeapRegionType type, 409 bool do_expand, 410 uint node_index = G1NUMA::AnyNodeIndex); 411 412 // Initialize a contiguous set of free regions of length num_regions 413 // and starting at index first so that they appear as a single 414 // humongous region. 415 HeapWord* humongous_obj_allocate_initialize_regions(HeapRegion* first_hr, 416 uint num_regions, 417 size_t word_size); 418 419 // Attempt to allocate a humongous object of the given size. Return 420 // NULL if unsuccessful. 421 HeapWord* humongous_obj_allocate(size_t word_size); 422 423 // The following two methods, allocate_new_tlab() and 424 // mem_allocate(), are the two main entry points from the runtime 425 // into the G1's allocation routines. They have the following 426 // assumptions: 427 // 428 // * They should both be called outside safepoints. 429 // 430 // * They should both be called without holding the Heap_lock. 431 // 432 // * All allocation requests for new TLABs should go to 433 // allocate_new_tlab(). 434 // 435 // * All non-TLAB allocation requests should go to mem_allocate(). 436 // 437 // * If either call cannot satisfy the allocation request using the 438 // current allocating region, they will try to get a new one. If 439 // this fails, they will attempt to do an evacuation pause and 440 // retry the allocation. 441 // 442 // * If all allocation attempts fail, even after trying to schedule 443 // an evacuation pause, allocate_new_tlab() will return NULL, 444 // whereas mem_allocate() will attempt a heap expansion and/or 445 // schedule a Full GC. 446 // 447 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 448 // should never be called with word_size being humongous. All 449 // humongous allocation requests should go to mem_allocate() which 450 // will satisfy them with a special path. 451 452 virtual HeapWord* allocate_new_tlab(size_t min_size, 453 size_t requested_size, 454 size_t* actual_size); 455 456 virtual HeapWord* mem_allocate(size_t word_size, 457 bool* gc_overhead_limit_was_exceeded); 458 459 // First-level mutator allocation attempt: try to allocate out of 460 // the mutator alloc region without taking the Heap_lock. This 461 // should only be used for non-humongous allocations. 462 inline HeapWord* attempt_allocation(size_t min_word_size, 463 size_t desired_word_size, 464 size_t* actual_word_size); 465 466 // Second-level mutator allocation attempt: take the Heap_lock and 467 // retry the allocation attempt, potentially scheduling a GC 468 // pause. This should only be used for non-humongous allocations. 469 HeapWord* attempt_allocation_slow(size_t word_size); 470 471 // Takes the Heap_lock and attempts a humongous allocation. It can 472 // potentially schedule a GC pause. 473 HeapWord* attempt_allocation_humongous(size_t word_size); 474 475 // Allocation attempt that should be called during safepoints (e.g., 476 // at the end of a successful GC). expect_null_mutator_alloc_region 477 // specifies whether the mutator alloc region is expected to be NULL 478 // or not. 479 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 480 bool expect_null_mutator_alloc_region); 481 482 // These methods are the "callbacks" from the G1AllocRegion class. 483 484 // For mutator alloc regions. 485 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force, uint node_index); 486 void retire_mutator_alloc_region(HeapRegion* alloc_region, 487 size_t allocated_bytes); 488 489 // For GC alloc regions. 490 bool has_more_regions(G1HeapRegionAttr dest); 491 HeapRegion* new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index); 492 void retire_gc_alloc_region(HeapRegion* alloc_region, 493 size_t allocated_bytes, G1HeapRegionAttr dest); 494 495 // - if explicit_gc is true, the GC is for a System.gc() etc, 496 // otherwise it's for a failed allocation. 497 // - if clear_all_soft_refs is true, all soft references should be 498 // cleared during the GC. 499 // - it returns false if it is unable to do the collection due to the 500 // GC locker being active, true otherwise. 501 bool do_full_collection(bool explicit_gc, 502 bool clear_all_soft_refs); 503 504 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 505 virtual void do_full_collection(bool clear_all_soft_refs); 506 507 // Callback from VM_G1CollectForAllocation operation. 508 // This function does everything necessary/possible to satisfy a 509 // failed allocation request (including collection, expansion, etc.) 510 HeapWord* satisfy_failed_allocation(size_t word_size, 511 bool* succeeded); 512 // Internal helpers used during full GC to split it up to 513 // increase readability. 514 void abort_concurrent_cycle(); 515 void verify_before_full_collection(bool explicit_gc); 516 void prepare_heap_for_full_collection(); 517 void prepare_heap_for_mutators(); 518 void abort_refinement(); 519 void verify_after_full_collection(); 520 void print_heap_after_full_collection(G1HeapTransition* heap_transition); 521 522 // Helper method for satisfy_failed_allocation() 523 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 524 bool do_gc, 525 bool clear_all_soft_refs, 526 bool expect_null_mutator_alloc_region, 527 bool* gc_succeeded); 528 529 // Attempting to expand the heap sufficiently 530 // to support an allocation of the given "word_size". If 531 // successful, perform the allocation and return the address of the 532 // allocated block, or else "NULL". 533 HeapWord* expand_and_allocate(size_t word_size); 534 535 // Process any reference objects discovered. 536 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 537 538 // If during a concurrent start pause we may install a pending list head which is not 539 // otherwise reachable, ensure that it is marked in the bitmap for concurrent marking 540 // to discover. 541 void make_pending_list_reachable(); 542 543 // Merges the information gathered on a per-thread basis for all worker threads 544 // during GC into global variables. 545 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states); 546 547 void verify_numa_regions(const char* desc); 548 549 public: 550 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; } 551 552 WorkGang* workers() const { return _workers; } 553 554 // Runs the given AbstractGangTask with the current active workers, 555 // returning the total time taken. 556 Tickspan run_task_timed(AbstractGangTask* task); 557 558 G1Allocator* allocator() { 559 return _allocator; 560 } 561 562 G1HeapVerifier* verifier() { 563 return _verifier; 564 } 565 566 G1MonitoringSupport* g1mm() { 567 assert(_g1mm != NULL, "should have been initialized"); 568 return _g1mm; 569 } 570 571 void resize_heap_if_necessary(); 572 573 G1NUMA* numa() const { return _numa; } 574 575 // Expand the garbage-first heap by at least the given size (in bytes!). 576 // Returns true if the heap was expanded by the requested amount; 577 // false otherwise. 578 // (Rounds up to a HeapRegion boundary.) 579 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL); 580 bool expand_single_region(uint node_index); 581 582 // Returns the PLAB statistics for a given destination. 583 inline G1EvacStats* alloc_buffer_stats(G1HeapRegionAttr dest); 584 585 // Determines PLAB size for a given destination. 586 inline size_t desired_plab_sz(G1HeapRegionAttr dest); 587 588 // Do anything common to GC's. 589 void gc_prologue(bool full); 590 void gc_epilogue(bool full); 591 592 // Does the given region fulfill remembered set based eager reclaim candidate requirements? 593 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const; 594 595 // Modify the reclaim candidate set and test for presence. 596 // These are only valid for starts_humongous regions. 597 inline void set_humongous_reclaim_candidate(uint region, bool value); 598 inline bool is_humongous_reclaim_candidate(uint region); 599 inline void set_has_humongous_reclaim_candidate(bool value); 600 601 // Remove from the reclaim candidate set. Also remove from the 602 // collection set so that later encounters avoid the slow path. 603 inline void set_humongous_is_live(oop obj); 604 605 // Register the given region to be part of the collection set. 606 inline void register_humongous_region_with_region_attr(uint index); 607 608 // We register a region with the fast "in collection set" test. We 609 // simply set to true the array slot corresponding to this region. 610 void register_young_region_with_region_attr(HeapRegion* r) { 611 _region_attr.set_in_young(r->hrm_index()); 612 } 613 inline void register_region_with_region_attr(HeapRegion* r); 614 inline void register_old_region_with_region_attr(HeapRegion* r); 615 inline void register_optional_region_with_region_attr(HeapRegion* r); 616 617 void clear_region_attr(const HeapRegion* hr) { 618 _region_attr.clear(hr); 619 } 620 621 void clear_region_attr() { 622 _region_attr.clear(); 623 } 624 625 // Verify that the G1RegionAttr remset tracking corresponds to actual remset tracking 626 // for all regions. 627 void verify_region_attr_remset_update() PRODUCT_RETURN; 628 629 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 630 631 // This is called at the start of either a concurrent cycle or a Full 632 // GC to update the number of old marking cycles started. 633 void increment_old_marking_cycles_started(); 634 635 // This is called at the end of either a concurrent cycle or a Full 636 // GC to update the number of old marking cycles completed. Those two 637 // can happen in a nested fashion, i.e., we start a concurrent 638 // cycle, a Full GC happens half-way through it which ends first, 639 // and then the cycle notices that a Full GC happened and ends 640 // too. The concurrent parameter is a boolean to help us do a bit 641 // tighter consistency checking in the method. If concurrent is 642 // false, the caller is the inner caller in the nesting (i.e., the 643 // Full GC). If concurrent is true, the caller is the outer caller 644 // in this nesting (i.e., the concurrent cycle). Further nesting is 645 // not currently supported. The end of this call also notifies 646 // the G1OldGCCount_lock in case a Java thread is waiting for a full 647 // GC to happen (e.g., it called System.gc() with 648 // +ExplicitGCInvokesConcurrent). 649 // whole_heap_examined should indicate that during that old marking 650 // cycle the whole heap has been examined for live objects (as opposed 651 // to only parts, or aborted before completion). 652 void increment_old_marking_cycles_completed(bool concurrent, bool whole_heap_examined); 653 654 uint old_marking_cycles_completed() { 655 return _old_marking_cycles_completed; 656 } 657 658 G1HRPrinter* hr_printer() { return &_hr_printer; } 659 660 // Allocates a new heap region instance. 661 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 662 663 // Allocate the highest free region in the reserved heap. This will commit 664 // regions as necessary. 665 HeapRegion* alloc_highest_free_region(); 666 667 // Frees a region by resetting its metadata and adding it to the free list 668 // passed as a parameter (this is usually a local list which will be appended 669 // to the master free list later or NULL if free list management is handled 670 // in another way). 671 // Callers must ensure they are the only one calling free on the given region 672 // at the same time. 673 void free_region(HeapRegion* hr, FreeRegionList* free_list); 674 675 // It dirties the cards that cover the block so that the post 676 // write barrier never queues anything when updating objects on this 677 // block. It is assumed (and in fact we assert) that the block 678 // belongs to a young region. 679 inline void dirty_young_block(HeapWord* start, size_t word_size); 680 681 // Frees a humongous region by collapsing it into individual regions 682 // and calling free_region() for each of them. The freed regions 683 // will be added to the free list that's passed as a parameter (this 684 // is usually a local list which will be appended to the master free 685 // list later). 686 // The method assumes that only a single thread is ever calling 687 // this for a particular region at once. 688 void free_humongous_region(HeapRegion* hr, 689 FreeRegionList* free_list); 690 691 // Facility for allocating in 'archive' regions in high heap memory and 692 // recording the allocated ranges. These should all be called from the 693 // VM thread at safepoints, without the heap lock held. They can be used 694 // to create and archive a set of heap regions which can be mapped at the 695 // same fixed addresses in a subsequent JVM invocation. 696 void begin_archive_alloc_range(bool open = false); 697 698 // Check if the requested size would be too large for an archive allocation. 699 bool is_archive_alloc_too_large(size_t word_size); 700 701 // Allocate memory of the requested size from the archive region. This will 702 // return NULL if the size is too large or if no memory is available. It 703 // does not trigger a garbage collection. 704 HeapWord* archive_mem_allocate(size_t word_size); 705 706 // Optionally aligns the end address and returns the allocated ranges in 707 // an array of MemRegions in order of ascending addresses. 708 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 709 size_t end_alignment_in_bytes = 0); 710 711 // Facility for allocating a fixed range within the heap and marking 712 // the containing regions as 'archive'. For use at JVM init time, when the 713 // caller may mmap archived heap data at the specified range(s). 714 // Verify that the MemRegions specified in the argument array are within the 715 // reserved heap. 716 bool check_archive_addresses(MemRegion* range, size_t count); 717 718 // Commit the appropriate G1 regions containing the specified MemRegions 719 // and mark them as 'archive' regions. The regions in the array must be 720 // non-overlapping and in order of ascending address. 721 bool alloc_archive_regions(MemRegion* range, size_t count, bool open); 722 723 // Insert any required filler objects in the G1 regions around the specified 724 // ranges to make the regions parseable. This must be called after 725 // alloc_archive_regions, and after class loading has occurred. 726 void fill_archive_regions(MemRegion* range, size_t count); 727 728 // For each of the specified MemRegions, uncommit the containing G1 regions 729 // which had been allocated by alloc_archive_regions. This should be called 730 // rather than fill_archive_regions at JVM init time if the archive file 731 // mapping failed, with the same non-overlapping and sorted MemRegion array. 732 void dealloc_archive_regions(MemRegion* range, size_t count); 733 734 oop materialize_archived_object(oop obj); 735 736 private: 737 738 // Shrink the garbage-first heap by at most the given size (in bytes!). 739 // (Rounds down to a HeapRegion boundary.) 740 void shrink(size_t shrink_bytes); 741 void shrink_helper(size_t expand_bytes); 742 743 #if TASKQUEUE_STATS 744 static void print_taskqueue_stats_hdr(outputStream* const st); 745 void print_taskqueue_stats() const; 746 void reset_taskqueue_stats(); 747 #endif // TASKQUEUE_STATS 748 749 // Schedule the VM operation that will do an evacuation pause to 750 // satisfy an allocation request of word_size. *succeeded will 751 // return whether the VM operation was successful (it did do an 752 // evacuation pause) or not (another thread beat us to it or the GC 753 // locker was active). Given that we should not be holding the 754 // Heap_lock when we enter this method, we will pass the 755 // gc_count_before (i.e., total_collections()) as a parameter since 756 // it has to be read while holding the Heap_lock. Currently, both 757 // methods that call do_collection_pause() release the Heap_lock 758 // before the call, so it's easy to read gc_count_before just before. 759 HeapWord* do_collection_pause(size_t word_size, 760 uint gc_count_before, 761 bool* succeeded, 762 GCCause::Cause gc_cause); 763 764 void wait_for_root_region_scanning(); 765 766 // Perform an incremental collection at a safepoint, possibly 767 // followed by a by-policy upgrade to a full collection. Returns 768 // false if unable to do the collection due to the GC locker being 769 // active, true otherwise. 770 // precondition: at safepoint on VM thread 771 // precondition: !is_gc_active() 772 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 773 774 // Helper for do_collection_pause_at_safepoint, containing the guts 775 // of the incremental collection pause, executed by the vm thread. 776 void do_collection_pause_at_safepoint_helper(double target_pause_time_ms); 777 778 G1HeapVerifier::G1VerifyType young_collection_verify_type() const; 779 void verify_before_young_collection(G1HeapVerifier::G1VerifyType type); 780 void verify_after_young_collection(G1HeapVerifier::G1VerifyType type); 781 782 void calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms); 783 784 // Actually do the work of evacuating the parts of the collection set. 785 void evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states); 786 void evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states); 787 private: 788 // Evacuate the next set of optional regions. 789 void evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states); 790 791 public: 792 void pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 793 void post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, 794 G1RedirtyCardsQueueSet* rdcqs, 795 G1ParScanThreadStateSet* pss); 796 797 void expand_heap_after_young_collection(); 798 // Update object copying statistics. 799 void record_obj_copy_mem_stats(); 800 801 // The hot card cache for remembered set insertion optimization. 802 G1HotCardCache* _hot_card_cache; 803 804 // The g1 remembered set of the heap. 805 G1RemSet* _rem_set; 806 807 // After a collection pause, convert the regions in the collection set into free 808 // regions. 809 void free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 810 811 // Abandon the current collection set without recording policy 812 // statistics or updating free lists. 813 void abandon_collection_set(G1CollectionSet* collection_set); 814 815 // The concurrent marker (and the thread it runs in.) 816 G1ConcurrentMark* _cm; 817 G1ConcurrentMarkThread* _cm_thread; 818 819 // The concurrent refiner. 820 G1ConcurrentRefine* _cr; 821 822 // The parallel task queues 823 G1ScannerTasksQueueSet *_task_queues; 824 825 // True iff a evacuation has failed in the current collection. 826 bool _evacuation_failed; 827 828 EvacuationFailedInfo* _evacuation_failed_info_array; 829 830 // Failed evacuations cause some logical from-space objects to have 831 // forwarding pointers to themselves. Reset them. 832 void remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs); 833 834 // Restore the objects in the regions in the collection set after an 835 // evacuation failure. 836 void restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs); 837 838 PreservedMarksSet _preserved_marks_set; 839 840 // Preserve the mark of "obj", if necessary, in preparation for its mark 841 // word being overwritten with a self-forwarding-pointer. 842 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m); 843 844 #ifndef PRODUCT 845 // Support for forcing evacuation failures. Analogous to 846 // PromotionFailureALot for the other collectors. 847 848 // Records whether G1EvacuationFailureALot should be in effect 849 // for the current GC 850 bool _evacuation_failure_alot_for_current_gc; 851 852 // Used to record the GC number for interval checking when 853 // determining whether G1EvaucationFailureALot is in effect 854 // for the current GC. 855 size_t _evacuation_failure_alot_gc_number; 856 857 // Count of the number of evacuations between failures. 858 volatile size_t _evacuation_failure_alot_count; 859 860 // Set whether G1EvacuationFailureALot should be in effect 861 // for the current GC (based upon the type of GC and which 862 // command line flags are set); 863 inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc, 864 bool during_concurrent_start, 865 bool mark_or_rebuild_in_progress); 866 867 inline void set_evacuation_failure_alot_for_current_gc(); 868 869 // Return true if it's time to cause an evacuation failure. 870 inline bool evacuation_should_fail(); 871 872 // Reset the G1EvacuationFailureALot counters. Should be called at 873 // the end of an evacuation pause in which an evacuation failure occurred. 874 inline void reset_evacuation_should_fail(); 875 #endif // !PRODUCT 876 877 // ("Weak") Reference processing support. 878 // 879 // G1 has 2 instances of the reference processor class. One 880 // (_ref_processor_cm) handles reference object discovery 881 // and subsequent processing during concurrent marking cycles. 882 // 883 // The other (_ref_processor_stw) handles reference object 884 // discovery and processing during full GCs and incremental 885 // evacuation pauses. 886 // 887 // During an incremental pause, reference discovery will be 888 // temporarily disabled for _ref_processor_cm and will be 889 // enabled for _ref_processor_stw. At the end of the evacuation 890 // pause references discovered by _ref_processor_stw will be 891 // processed and discovery will be disabled. The previous 892 // setting for reference object discovery for _ref_processor_cm 893 // will be re-instated. 894 // 895 // At the start of marking: 896 // * Discovery by the CM ref processor is verified to be inactive 897 // and it's discovered lists are empty. 898 // * Discovery by the CM ref processor is then enabled. 899 // 900 // At the end of marking: 901 // * Any references on the CM ref processor's discovered 902 // lists are processed (possibly MT). 903 // 904 // At the start of full GC we: 905 // * Disable discovery by the CM ref processor and 906 // empty CM ref processor's discovered lists 907 // (without processing any entries). 908 // * Verify that the STW ref processor is inactive and it's 909 // discovered lists are empty. 910 // * Temporarily set STW ref processor discovery as single threaded. 911 // * Temporarily clear the STW ref processor's _is_alive_non_header 912 // field. 913 // * Finally enable discovery by the STW ref processor. 914 // 915 // The STW ref processor is used to record any discovered 916 // references during the full GC. 917 // 918 // At the end of a full GC we: 919 // * Enqueue any reference objects discovered by the STW ref processor 920 // that have non-live referents. This has the side-effect of 921 // making the STW ref processor inactive by disabling discovery. 922 // * Verify that the CM ref processor is still inactive 923 // and no references have been placed on it's discovered 924 // lists (also checked as a precondition during concurrent start). 925 926 // The (stw) reference processor... 927 ReferenceProcessor* _ref_processor_stw; 928 929 // During reference object discovery, the _is_alive_non_header 930 // closure (if non-null) is applied to the referent object to 931 // determine whether the referent is live. If so then the 932 // reference object does not need to be 'discovered' and can 933 // be treated as a regular oop. This has the benefit of reducing 934 // the number of 'discovered' reference objects that need to 935 // be processed. 936 // 937 // Instance of the is_alive closure for embedding into the 938 // STW reference processor as the _is_alive_non_header field. 939 // Supplying a value for the _is_alive_non_header field is 940 // optional but doing so prevents unnecessary additions to 941 // the discovered lists during reference discovery. 942 G1STWIsAliveClosure _is_alive_closure_stw; 943 944 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw; 945 946 // The (concurrent marking) reference processor... 947 ReferenceProcessor* _ref_processor_cm; 948 949 // Instance of the concurrent mark is_alive closure for embedding 950 // into the Concurrent Marking reference processor as the 951 // _is_alive_non_header field. Supplying a value for the 952 // _is_alive_non_header field is optional but doing so prevents 953 // unnecessary additions to the discovered lists during reference 954 // discovery. 955 G1CMIsAliveClosure _is_alive_closure_cm; 956 957 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm; 958 public: 959 960 G1ScannerTasksQueue* task_queue(uint i) const; 961 962 uint num_task_queues() const; 963 964 // Create a G1CollectedHeap. 965 // Must call the initialize method afterwards. 966 // May not return if something goes wrong. 967 G1CollectedHeap(); 968 969 private: 970 jint initialize_concurrent_refinement(); 971 jint initialize_young_gen_sampling_thread(); 972 public: 973 // Initialize the G1CollectedHeap to have the initial and 974 // maximum sizes and remembered and barrier sets 975 // specified by the policy object. 976 jint initialize(); 977 978 virtual void stop(); 979 virtual void safepoint_synchronize_begin(); 980 virtual void safepoint_synchronize_end(); 981 982 // Does operations required after initialization has been done. 983 void post_initialize(); 984 985 // Initialize weak reference processing. 986 void ref_processing_init(); 987 988 virtual Name kind() const { 989 return CollectedHeap::G1; 990 } 991 992 virtual const char* name() const { 993 return "G1"; 994 } 995 996 const G1CollectorState* collector_state() const { return &_collector_state; } 997 G1CollectorState* collector_state() { return &_collector_state; } 998 999 // The current policy object for the collector. 1000 G1Policy* policy() const { return _policy; } 1001 // The remembered set. 1002 G1RemSet* rem_set() const { return _rem_set; } 1003 1004 inline G1GCPhaseTimes* phase_times() const; 1005 1006 HeapRegionManager* hrm() const { return _hrm; } 1007 1008 const G1CollectionSet* collection_set() const { return &_collection_set; } 1009 G1CollectionSet* collection_set() { return &_collection_set; } 1010 1011 virtual SoftRefPolicy* soft_ref_policy(); 1012 1013 virtual void initialize_serviceability(); 1014 virtual MemoryUsage memory_usage(); 1015 virtual GrowableArray<GCMemoryManager*> memory_managers(); 1016 virtual GrowableArray<MemoryPool*> memory_pools(); 1017 1018 // Try to minimize the remembered set. 1019 void scrub_rem_set(); 1020 1021 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 1022 void iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id); 1023 1024 // The shared block offset table array. 1025 G1BlockOffsetTable* bot() const { return _bot; } 1026 1027 // Reference Processing accessors 1028 1029 // The STW reference processor.... 1030 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1031 1032 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1033 1034 // The Concurrent Marking reference processor... 1035 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1036 1037 size_t unused_committed_regions_in_bytes() const; 1038 1039 virtual size_t capacity() const; 1040 virtual size_t used() const; 1041 // This should be called when we're not holding the heap lock. The 1042 // result might be a bit inaccurate. 1043 size_t used_unlocked() const; 1044 size_t recalculate_used() const; 1045 1046 // These virtual functions do the actual allocation. 1047 // Some heaps may offer a contiguous region for shared non-blocking 1048 // allocation, via inlined code (by exporting the address of the top and 1049 // end fields defining the extent of the contiguous allocation region.) 1050 // But G1CollectedHeap doesn't yet support this. 1051 1052 virtual bool is_maximal_no_gc() const { 1053 return _hrm->available() == 0; 1054 } 1055 1056 // Returns whether there are any regions left in the heap for allocation. 1057 bool has_regions_left_for_allocation() const { 1058 return !is_maximal_no_gc() || num_free_regions() != 0; 1059 } 1060 1061 // The current number of regions in the heap. 1062 uint num_regions() const { return _hrm->length(); } 1063 1064 // The max number of regions in the heap. 1065 uint max_regions() const { return _hrm->max_length(); } 1066 1067 // Max number of regions that can be comitted. 1068 uint max_expandable_regions() const { return _hrm->max_expandable_length(); } 1069 1070 // The number of regions that are completely free. 1071 uint num_free_regions() const { return _hrm->num_free_regions(); } 1072 1073 // The number of regions that can be allocated into. 1074 uint num_free_or_available_regions() const { return num_free_regions() + _hrm->available(); } 1075 1076 MemoryUsage get_auxiliary_data_memory_usage() const { 1077 return _hrm->get_auxiliary_data_memory_usage(); 1078 } 1079 1080 // The number of regions that are not completely free. 1081 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1082 1083 #ifdef ASSERT 1084 bool is_on_master_free_list(HeapRegion* hr) { 1085 return _hrm->is_free(hr); 1086 } 1087 #endif // ASSERT 1088 1089 inline void old_set_add(HeapRegion* hr); 1090 inline void old_set_remove(HeapRegion* hr); 1091 1092 inline void archive_set_add(HeapRegion* hr); 1093 1094 size_t non_young_capacity_bytes() { 1095 return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes; 1096 } 1097 1098 // Determine whether the given region is one that we are using as an 1099 // old GC alloc region. 1100 bool is_old_gc_alloc_region(HeapRegion* hr); 1101 1102 // Perform a collection of the heap; intended for use in implementing 1103 // "System.gc". This probably implies as full a collection as the 1104 // "CollectedHeap" supports. 1105 virtual void collect(GCCause::Cause cause); 1106 1107 // Perform a collection of the heap with the given cause. 1108 // Returns whether this collection actually executed. 1109 bool try_collect(GCCause::Cause cause); 1110 1111 // True iff an evacuation has failed in the most-recent collection. 1112 bool evacuation_failed() { return _evacuation_failed; } 1113 1114 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed); 1115 void prepend_to_freelist(FreeRegionList* list); 1116 void decrement_summary_bytes(size_t bytes); 1117 1118 virtual bool is_in(const void* p) const; 1119 #ifdef ASSERT 1120 // Returns whether p is in one of the available areas of the heap. Slow but 1121 // extensive version. 1122 bool is_in_exact(const void* p) const; 1123 #endif 1124 1125 // Return "TRUE" iff the given object address is within the collection 1126 // set. Assumes that the reference points into the heap. 1127 inline bool is_in_cset(const HeapRegion *hr); 1128 inline bool is_in_cset(oop obj); 1129 inline bool is_in_cset(HeapWord* addr); 1130 1131 inline bool is_in_cset_or_humongous(const oop obj); 1132 1133 private: 1134 // This array is used for a quick test on whether a reference points into 1135 // the collection set or not. Each of the array's elements denotes whether the 1136 // corresponding region is in the collection set or not. 1137 G1HeapRegionAttrBiasedMappedArray _region_attr; 1138 1139 public: 1140 1141 inline G1HeapRegionAttr region_attr(const void* obj) const; 1142 inline G1HeapRegionAttr region_attr(uint idx) const; 1143 1144 // Return "TRUE" iff the given object address is in the reserved 1145 // region of g1. 1146 bool is_in_g1_reserved(const void* p) const { 1147 return _hrm->reserved().contains(p); 1148 } 1149 1150 // Returns a MemRegion that corresponds to the space that has been 1151 // reserved for the heap 1152 MemRegion g1_reserved() const { 1153 return _hrm->reserved(); 1154 } 1155 1156 MemRegion reserved_region() const { 1157 return _reserved; 1158 } 1159 1160 HeapWord* base() const { 1161 return _reserved.start(); 1162 } 1163 1164 bool is_in_reserved(const void* addr) const { 1165 return _reserved.contains(addr); 1166 } 1167 1168 G1HotCardCache* hot_card_cache() const { return _hot_card_cache; } 1169 1170 G1CardTable* card_table() const { 1171 return _card_table; 1172 } 1173 1174 // Iteration functions. 1175 1176 void object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer); 1177 1178 // Iterate over all objects, calling "cl.do_object" on each. 1179 virtual void object_iterate(ObjectClosure* cl); 1180 1181 virtual ParallelObjectIterator* parallel_object_iterator(uint thread_num); 1182 1183 // Keep alive an object that was loaded with AS_NO_KEEPALIVE. 1184 virtual void keep_alive(oop obj); 1185 1186 // Iterate over heap regions, in address order, terminating the 1187 // iteration early if the "do_heap_region" method returns "true". 1188 void heap_region_iterate(HeapRegionClosure* blk) const; 1189 1190 // Return the region with the given index. It assumes the index is valid. 1191 inline HeapRegion* region_at(uint index) const; 1192 inline HeapRegion* region_at_or_null(uint index) const; 1193 1194 // Return the next region (by index) that is part of the same 1195 // humongous object that hr is part of. 1196 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1197 1198 // Calculate the region index of the given address. Given address must be 1199 // within the heap. 1200 inline uint addr_to_region(HeapWord* addr) const; 1201 1202 inline HeapWord* bottom_addr_for_region(uint index) const; 1203 1204 // Two functions to iterate over the heap regions in parallel. Threads 1205 // compete using the HeapRegionClaimer to claim the regions before 1206 // applying the closure on them. 1207 // The _from_worker_offset version uses the HeapRegionClaimer and 1208 // the worker id to calculate a start offset to prevent all workers to 1209 // start from the point. 1210 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 1211 HeapRegionClaimer* hrclaimer, 1212 uint worker_id) const; 1213 1214 void heap_region_par_iterate_from_start(HeapRegionClosure* cl, 1215 HeapRegionClaimer* hrclaimer) const; 1216 1217 // Iterate over all regions in the collection set in parallel. 1218 void collection_set_par_iterate_all(HeapRegionClosure* cl, 1219 HeapRegionClaimer* hr_claimer, 1220 uint worker_id); 1221 1222 // Iterate over all regions currently in the current collection set. 1223 void collection_set_iterate_all(HeapRegionClosure* blk); 1224 1225 // Iterate over the regions in the current increment of the collection set. 1226 // Starts the iteration so that the start regions of a given worker id over the 1227 // set active_workers are evenly spread across the set of collection set regions 1228 // to be iterated. 1229 // The variant with the HeapRegionClaimer guarantees that the closure will be 1230 // applied to a particular region exactly once. 1231 void collection_set_iterate_increment_from(HeapRegionClosure *blk, uint worker_id) { 1232 collection_set_iterate_increment_from(blk, NULL, worker_id); 1233 } 1234 void collection_set_iterate_increment_from(HeapRegionClosure *blk, HeapRegionClaimer* hr_claimer, uint worker_id); 1235 1236 // Returns the HeapRegion that contains addr. addr must not be NULL. 1237 template <class T> 1238 inline HeapRegion* heap_region_containing(const T addr) const; 1239 1240 // Returns the HeapRegion that contains addr, or NULL if that is an uncommitted 1241 // region. addr must not be NULL. 1242 template <class T> 1243 inline HeapRegion* heap_region_containing_or_null(const T addr) const; 1244 1245 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1246 // each address in the (reserved) heap is a member of exactly 1247 // one block. The defining characteristic of a block is that it is 1248 // possible to find its size, and thus to progress forward to the next 1249 // block. (Blocks may be of different sizes.) Thus, blocks may 1250 // represent Java objects, or they might be free blocks in a 1251 // free-list-based heap (or subheap), as long as the two kinds are 1252 // distinguishable and the size of each is determinable. 1253 1254 // Returns the address of the start of the "block" that contains the 1255 // address "addr". We say "blocks" instead of "object" since some heaps 1256 // may not pack objects densely; a chunk may either be an object or a 1257 // non-object. 1258 HeapWord* block_start(const void* addr) const; 1259 1260 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1261 // the block is an object. 1262 bool block_is_obj(const HeapWord* addr) const; 1263 1264 // Section on thread-local allocation buffers (TLABs) 1265 // See CollectedHeap for semantics. 1266 1267 bool supports_tlab_allocation() const; 1268 size_t tlab_capacity(Thread* ignored) const; 1269 size_t tlab_used(Thread* ignored) const; 1270 size_t max_tlab_size() const; 1271 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1272 1273 inline bool is_in_young(const oop obj); 1274 1275 // Returns "true" iff the given word_size is "very large". 1276 static bool is_humongous(size_t word_size) { 1277 // Note this has to be strictly greater-than as the TLABs 1278 // are capped at the humongous threshold and we want to 1279 // ensure that we don't try to allocate a TLAB as 1280 // humongous and that we don't allocate a humongous 1281 // object in a TLAB. 1282 return word_size > _humongous_object_threshold_in_words; 1283 } 1284 1285 // Returns the humongous threshold for a specific region size 1286 static size_t humongous_threshold_for(size_t region_size) { 1287 return (region_size / 2); 1288 } 1289 1290 // Returns the number of regions the humongous object of the given word size 1291 // requires. 1292 static size_t humongous_obj_size_in_regions(size_t word_size); 1293 1294 // Print the maximum heap capacity. 1295 virtual size_t max_capacity() const; 1296 1297 // Return the size of reserved memory. Returns different value than max_capacity() when AllocateOldGenAt is used. 1298 virtual size_t max_reserved_capacity() const; 1299 1300 Tickspan time_since_last_collection() const { return Ticks::now() - _collection_pause_end; } 1301 1302 // Convenience function to be used in situations where the heap type can be 1303 // asserted to be this type. 1304 static G1CollectedHeap* heap() { 1305 return named_heap<G1CollectedHeap>(CollectedHeap::G1); 1306 } 1307 1308 void set_region_short_lived_locked(HeapRegion* hr); 1309 // add appropriate methods for any other surv rate groups 1310 1311 const G1SurvivorRegions* survivor() const { return &_survivor; } 1312 1313 uint eden_regions_count() const { return _eden.length(); } 1314 uint eden_regions_count(uint node_index) const { return _eden.regions_on_node(node_index); } 1315 uint survivor_regions_count() const { return _survivor.length(); } 1316 uint survivor_regions_count(uint node_index) const { return _survivor.regions_on_node(node_index); } 1317 size_t eden_regions_used_bytes() const { return _eden.used_bytes(); } 1318 size_t survivor_regions_used_bytes() const { return _survivor.used_bytes(); } 1319 uint young_regions_count() const { return _eden.length() + _survivor.length(); } 1320 uint old_regions_count() const { return _old_set.length(); } 1321 uint archive_regions_count() const { return _archive_set.length(); } 1322 uint humongous_regions_count() const { return _humongous_set.length(); } 1323 1324 #ifdef ASSERT 1325 bool check_young_list_empty(); 1326 #endif 1327 1328 // *** Stuff related to concurrent marking. It's not clear to me that so 1329 // many of these need to be public. 1330 1331 // The functions below are helper functions that a subclass of 1332 // "CollectedHeap" can use in the implementation of its virtual 1333 // functions. 1334 // This performs a concurrent marking of the live objects in a 1335 // bitmap off to the side. 1336 void do_concurrent_mark(); 1337 1338 bool is_marked_next(oop obj) const; 1339 1340 // Determine if an object is dead, given the object and also 1341 // the region to which the object belongs. An object is dead 1342 // iff a) it was not allocated since the last mark, b) it 1343 // is not marked, and c) it is not in an archive region. 1344 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1345 return 1346 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) && 1347 !hr->is_archive(); 1348 } 1349 1350 // This function returns true when an object has been 1351 // around since the previous marking and hasn't yet 1352 // been marked during this marking, and is not in an archive region. 1353 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1354 return 1355 !hr->obj_allocated_since_next_marking(obj) && 1356 !is_marked_next(obj) && 1357 !hr->is_archive(); 1358 } 1359 1360 // Determine if an object is dead, given only the object itself. 1361 // This will find the region to which the object belongs and 1362 // then call the region version of the same function. 1363 1364 // Added if it is NULL it isn't dead. 1365 1366 inline bool is_obj_dead(const oop obj) const; 1367 1368 inline bool is_obj_ill(const oop obj) const; 1369 1370 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const; 1371 inline bool is_obj_dead_full(const oop obj) const; 1372 1373 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1374 1375 // Refinement 1376 1377 G1ConcurrentRefine* concurrent_refine() const { return _cr; } 1378 1379 // Optimized nmethod scanning support routines 1380 1381 // Register the given nmethod with the G1 heap. 1382 virtual void register_nmethod(nmethod* nm); 1383 1384 // Unregister the given nmethod from the G1 heap. 1385 virtual void unregister_nmethod(nmethod* nm); 1386 1387 // No nmethod flushing needed. 1388 virtual void flush_nmethod(nmethod* nm) {} 1389 1390 // No nmethod verification implemented. 1391 virtual void verify_nmethod(nmethod* nm) {} 1392 1393 // Free up superfluous code root memory. 1394 void purge_code_root_memory(); 1395 1396 // Rebuild the strong code root lists for each region 1397 // after a full GC. 1398 void rebuild_strong_code_roots(); 1399 1400 // Partial cleaning of VM internal data structures. 1401 void string_dedup_cleaning(BoolObjectClosure* is_alive, 1402 OopClosure* keep_alive, 1403 G1GCPhaseTimes* phase_times = NULL); 1404 1405 // Performs cleaning of data structures after class unloading. 1406 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); 1407 1408 // Redirty logged cards in the refinement queue. 1409 void redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs); 1410 1411 // Verification 1412 1413 // Deduplicate the string 1414 virtual void deduplicate_string(oop str); 1415 1416 // Perform any cleanup actions necessary before allowing a verification. 1417 virtual void prepare_for_verify(); 1418 1419 // Perform verification. 1420 1421 // vo == UsePrevMarking -> use "prev" marking information, 1422 // vo == UseNextMarking -> use "next" marking information 1423 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS 1424 // 1425 // NOTE: Only the "prev" marking information is guaranteed to be 1426 // consistent most of the time, so most calls to this should use 1427 // vo == UsePrevMarking. 1428 // Currently, there is only one case where this is called with 1429 // vo == UseNextMarking, which is to verify the "next" marking 1430 // information at the end of remark. 1431 // Currently there is only one place where this is called with 1432 // vo == UseFullMarking, which is to verify the marking during a 1433 // full GC. 1434 void verify(VerifyOption vo); 1435 1436 // WhiteBox testing support. 1437 virtual bool supports_concurrent_gc_breakpoints() const; 1438 bool is_heterogeneous_heap() const; 1439 1440 virtual WorkGang* get_safepoint_workers() { return _workers; } 1441 1442 // The methods below are here for convenience and dispatch the 1443 // appropriate method depending on value of the given VerifyOption 1444 // parameter. The values for that parameter, and their meanings, 1445 // are the same as those above. 1446 1447 bool is_obj_dead_cond(const oop obj, 1448 const HeapRegion* hr, 1449 const VerifyOption vo) const; 1450 1451 bool is_obj_dead_cond(const oop obj, 1452 const VerifyOption vo) const; 1453 1454 G1HeapSummary create_g1_heap_summary(); 1455 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1456 1457 // Printing 1458 private: 1459 void print_heap_regions() const; 1460 void print_regions_on(outputStream* st) const; 1461 1462 public: 1463 virtual void print_on(outputStream* st) const; 1464 virtual void print_extended_on(outputStream* st) const; 1465 virtual void print_on_error(outputStream* st) const; 1466 1467 virtual void gc_threads_do(ThreadClosure* tc) const; 1468 1469 // Override 1470 void print_tracing_info() const; 1471 1472 // The following two methods are helpful for debugging RSet issues. 1473 void print_cset_rsets() PRODUCT_RETURN; 1474 void print_all_rsets() PRODUCT_RETURN; 1475 1476 // Used to print information about locations in the hs_err file. 1477 virtual bool print_location(outputStream* st, void* addr) const; 1478 }; 1479 1480 class G1ParEvacuateFollowersClosure : public VoidClosure { 1481 private: 1482 double _start_term; 1483 double _term_time; 1484 size_t _term_attempts; 1485 1486 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 1487 void end_term_time() { _term_time += (os::elapsedTime() - _start_term); } 1488 protected: 1489 G1CollectedHeap* _g1h; 1490 G1ParScanThreadState* _par_scan_state; 1491 G1ScannerTasksQueueSet* _queues; 1492 TaskTerminator* _terminator; 1493 G1GCPhaseTimes::GCParPhases _phase; 1494 1495 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 1496 G1ScannerTasksQueueSet* queues() { return _queues; } 1497 TaskTerminator* terminator() { return _terminator; } 1498 1499 public: 1500 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 1501 G1ParScanThreadState* par_scan_state, 1502 G1ScannerTasksQueueSet* queues, 1503 TaskTerminator* terminator, 1504 G1GCPhaseTimes::GCParPhases phase) 1505 : _start_term(0.0), _term_time(0.0), _term_attempts(0), 1506 _g1h(g1h), _par_scan_state(par_scan_state), 1507 _queues(queues), _terminator(terminator), _phase(phase) {} 1508 1509 void do_void(); 1510 1511 double term_time() const { return _term_time; } 1512 size_t term_attempts() const { return _term_attempts; } 1513 1514 private: 1515 inline bool offer_termination(); 1516 }; 1517 1518 #endif // SHARE_GC_G1_G1COLLECTEDHEAP_HPP