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