1 /* 2 * Copyright (c) 2001, 2019, 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/g1DirtyCardQueue.hpp" 35 #include "gc/g1/g1EdenRegions.hpp" 36 #include "gc/g1/g1EvacFailure.hpp" 37 #include "gc/g1/g1EvacStats.hpp" 38 #include "gc/g1/g1EvacuationInfo.hpp" 39 #include "gc/g1/g1GCPhaseTimes.hpp" 40 #include "gc/g1/g1HeapTransition.hpp" 41 #include "gc/g1/g1HeapVerifier.hpp" 42 #include "gc/g1/g1HRPrinter.hpp" 43 #include "gc/g1/g1InCSetState.hpp" 44 #include "gc/g1/g1MonitoringSupport.hpp" 45 #include "gc/g1/g1SurvivorRegions.hpp" 46 #include "gc/g1/g1YCTypes.hpp" 47 #include "gc/g1/heapRegionManager.hpp" 48 #include "gc/g1/heapRegionSet.hpp" 49 #include "gc/g1/heterogeneousHeapRegionManager.hpp" 50 #include "gc/shared/barrierSet.hpp" 51 #include "gc/shared/collectedHeap.hpp" 52 #include "gc/shared/gcHeapSummary.hpp" 53 #include "gc/shared/plab.hpp" 54 #include "gc/shared/preservedMarks.hpp" 55 #include "gc/shared/softRefPolicy.hpp" 56 #include "memory/memRegion.hpp" 57 #include "utilities/stack.hpp" 58 59 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 60 // It uses the "Garbage First" heap organization and algorithm, which 61 // may combine concurrent marking with parallel, incremental compaction of 62 // heap subsets that will yield large amounts of garbage. 63 64 // Forward declarations 65 class HeapRegion; 66 class GenerationSpec; 67 class G1ParScanThreadState; 68 class G1ParScanThreadStateSet; 69 class G1ParScanThreadState; 70 class MemoryPool; 71 class MemoryManager; 72 class ObjectClosure; 73 class SpaceClosure; 74 class CompactibleSpaceClosure; 75 class Space; 76 class G1CollectionSet; 77 class G1CollectorPolicy; 78 class G1Policy; 79 class G1HotCardCache; 80 class G1RemSet; 81 class G1YoungRemSetSamplingThread; 82 class HeapRegionRemSetIterator; 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 G1FreeCollectionSetTask; 134 friend class VM_CollectForMetadataAllocation; 135 friend class VM_G1CollectForAllocation; 136 friend class VM_G1CollectFull; 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 G1ParTask; 147 friend class G1PLABAllocator; 148 friend class G1PrepareCompactClosure; 149 150 // Other related classes. 151 friend class HeapRegionClaimer; 152 153 // Testing classes. 154 friend class G1CheckCSetFastTableClosure; 155 156 private: 157 G1YoungRemSetSamplingThread* _young_gen_sampling_thread; 158 159 WorkGang* _workers; 160 G1CollectorPolicy* _collector_policy; 161 G1CardTable* _card_table; 162 163 SoftRefPolicy _soft_ref_policy; 164 165 static size_t _humongous_object_threshold_in_words; 166 167 // These sets keep track of old, archive and humongous regions respectively. 168 HeapRegionSet _old_set; 169 HeapRegionSet _archive_set; 170 HeapRegionSet _humongous_set; 171 172 void eagerly_reclaim_humongous_regions(); 173 // Start a new incremental collection set for the next pause. 174 void start_new_collection_set(); 175 176 // The block offset table for the G1 heap. 177 G1BlockOffsetTable* _bot; 178 179 // Tears down the region sets / lists so that they are empty and the 180 // regions on the heap do not belong to a region set / list. The 181 // only exception is the humongous set which we leave unaltered. If 182 // free_list_only is true, it will only tear down the master free 183 // list. It is called before a Full GC (free_list_only == false) or 184 // before heap shrinking (free_list_only == true). 185 void tear_down_region_sets(bool free_list_only); 186 187 // Rebuilds the region sets / lists so that they are repopulated to 188 // reflect the contents of the heap. The only exception is the 189 // humongous set which was not torn down in the first place. If 190 // free_list_only is true, it will only rebuild the master free 191 // list. It is called after a Full GC (free_list_only == false) or 192 // after heap shrinking (free_list_only == true). 193 void rebuild_region_sets(bool free_list_only); 194 195 // Callback for region mapping changed events. 196 G1RegionMappingChangedListener _listener; 197 198 // The sequence of all heap regions in the heap. 199 HeapRegionManager* _hrm; 200 201 // Manages all allocations with regions except humongous object allocations. 202 G1Allocator* _allocator; 203 204 // Manages all heap verification. 205 G1HeapVerifier* _verifier; 206 207 // Outside of GC pauses, the number of bytes used in all regions other 208 // than the current allocation region(s). 209 size_t _summary_bytes_used; 210 211 void increase_used(size_t bytes); 212 void decrease_used(size_t bytes); 213 214 void set_used(size_t bytes); 215 216 // Class that handles archive allocation ranges. 217 G1ArchiveAllocator* _archive_allocator; 218 219 // GC allocation statistics policy for survivors. 220 G1EvacStats _survivor_evac_stats; 221 222 // GC allocation statistics policy for tenured objects. 223 G1EvacStats _old_evac_stats; 224 225 // It specifies whether we should attempt to expand the heap after a 226 // region allocation failure. If heap expansion fails we set this to 227 // false so that we don't re-attempt the heap expansion (it's likely 228 // that subsequent expansion attempts will also fail if one fails). 229 // Currently, it is only consulted during GC and it's reset at the 230 // start of each GC. 231 bool _expand_heap_after_alloc_failure; 232 233 // Helper for monitoring and management support. 234 G1MonitoringSupport* _g1mm; 235 236 // Records whether the region at the given index is (still) a 237 // candidate for eager reclaim. Only valid for humongous start 238 // regions; other regions have unspecified values. Humongous start 239 // regions are initialized at start of collection pause, with 240 // candidates removed from the set as they are found reachable from 241 // roots or the young generation. 242 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 243 protected: 244 bool default_value() const { return false; } 245 public: 246 void clear() { G1BiasedMappedArray<bool>::clear(); } 247 void set_candidate(uint region, bool value) { 248 set_by_index(region, value); 249 } 250 bool is_candidate(uint region) { 251 return get_by_index(region); 252 } 253 }; 254 255 HumongousReclaimCandidates _humongous_reclaim_candidates; 256 // Stores whether during humongous object registration we found candidate regions. 257 // If not, we can skip a few steps. 258 bool _has_humongous_reclaim_candidates; 259 260 G1HRPrinter _hr_printer; 261 262 // It decides whether an explicit GC should start a concurrent cycle 263 // instead of doing a STW GC. Currently, a concurrent cycle is 264 // explicitly started if: 265 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 266 // (b) cause == _g1_humongous_allocation 267 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 268 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 269 // (e) cause == _wb_conc_mark 270 bool should_do_concurrent_full_gc(GCCause::Cause cause); 271 272 // Return true if should upgrade to full gc after an incremental one. 273 bool should_upgrade_to_full_gc(GCCause::Cause cause); 274 275 // indicates whether we are in young or mixed GC mode 276 G1CollectorState _collector_state; 277 278 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 279 // concurrent cycles) we have started. 280 volatile uint _old_marking_cycles_started; 281 282 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 283 // concurrent cycles) we have completed. 284 volatile uint _old_marking_cycles_completed; 285 286 // This is a non-product method that is helpful for testing. It is 287 // called at the end of a GC and artificially expands the heap by 288 // allocating a number of dead regions. This way we can induce very 289 // frequent marking cycles and stress the cleanup / concurrent 290 // cleanup code more (as all the regions that will be allocated by 291 // this method will be found dead by the marking cycle). 292 void allocate_dummy_regions() PRODUCT_RETURN; 293 294 // If the HR printer is active, dump the state of the regions in the 295 // heap after a compaction. 296 void print_hrm_post_compaction(); 297 298 // Create a memory mapper for auxiliary data structures of the given size and 299 // translation factor. 300 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 301 size_t size, 302 size_t translation_factor); 303 304 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 305 306 // These are macros so that, if the assert fires, we get the correct 307 // line number, file, etc. 308 309 #define heap_locking_asserts_params(_extra_message_) \ 310 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 311 (_extra_message_), \ 312 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 313 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 314 BOOL_TO_STR(Thread::current()->is_VM_thread()) 315 316 #define assert_heap_locked() \ 317 do { \ 318 assert(Heap_lock->owned_by_self(), \ 319 heap_locking_asserts_params("should be holding the Heap_lock")); \ 320 } while (0) 321 322 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 323 do { \ 324 assert(Heap_lock->owned_by_self() || \ 325 (SafepointSynchronize::is_at_safepoint() && \ 326 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 327 heap_locking_asserts_params("should be holding the Heap_lock or " \ 328 "should be at a safepoint")); \ 329 } while (0) 330 331 #define assert_heap_locked_and_not_at_safepoint() \ 332 do { \ 333 assert(Heap_lock->owned_by_self() && \ 334 !SafepointSynchronize::is_at_safepoint(), \ 335 heap_locking_asserts_params("should be holding the Heap_lock and " \ 336 "should not be at a safepoint")); \ 337 } while (0) 338 339 #define assert_heap_not_locked() \ 340 do { \ 341 assert(!Heap_lock->owned_by_self(), \ 342 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 343 } while (0) 344 345 #define assert_heap_not_locked_and_not_at_safepoint() \ 346 do { \ 347 assert(!Heap_lock->owned_by_self() && \ 348 !SafepointSynchronize::is_at_safepoint(), \ 349 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 350 "should not be at a safepoint")); \ 351 } while (0) 352 353 #define assert_at_safepoint_on_vm_thread() \ 354 do { \ 355 assert_at_safepoint(); \ 356 assert(Thread::current_or_null() != NULL, "no current thread"); \ 357 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \ 358 } while (0) 359 360 const char* young_gc_name() const; 361 362 // The young region list. 363 G1EdenRegions _eden; 364 G1SurvivorRegions _survivor; 365 366 STWGCTimer* _gc_timer_stw; 367 368 G1NewTracer* _gc_tracer_stw; 369 370 // The current policy object for the collector. 371 G1Policy* _policy; 372 G1HeapSizingPolicy* _heap_sizing_policy; 373 374 G1CollectionSet _collection_set; 375 376 // Try to allocate a single non-humongous HeapRegion sufficient for 377 // an allocation of the given word_size. If do_expand is true, 378 // attempt to expand the heap if necessary to satisfy the allocation 379 // request. 'type' takes the type of region to be allocated. (Use constants 380 // Old, Eden, Humongous, Survivor defined in HeapRegionType.) 381 HeapRegion* new_region(size_t word_size, HeapRegionType type, bool do_expand); 382 383 // Initialize a contiguous set of free regions of length num_regions 384 // and starting at index first so that they appear as a single 385 // humongous region. 386 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 387 uint num_regions, 388 size_t word_size); 389 390 // Attempt to allocate a humongous object of the given size. Return 391 // NULL if unsuccessful. 392 HeapWord* humongous_obj_allocate(size_t word_size); 393 394 // The following two methods, allocate_new_tlab() and 395 // mem_allocate(), are the two main entry points from the runtime 396 // into the G1's allocation routines. They have the following 397 // assumptions: 398 // 399 // * They should both be called outside safepoints. 400 // 401 // * They should both be called without holding the Heap_lock. 402 // 403 // * All allocation requests for new TLABs should go to 404 // allocate_new_tlab(). 405 // 406 // * All non-TLAB allocation requests should go to mem_allocate(). 407 // 408 // * If either call cannot satisfy the allocation request using the 409 // current allocating region, they will try to get a new one. If 410 // this fails, they will attempt to do an evacuation pause and 411 // retry the allocation. 412 // 413 // * If all allocation attempts fail, even after trying to schedule 414 // an evacuation pause, allocate_new_tlab() will return NULL, 415 // whereas mem_allocate() will attempt a heap expansion and/or 416 // schedule a Full GC. 417 // 418 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 419 // should never be called with word_size being humongous. All 420 // humongous allocation requests should go to mem_allocate() which 421 // will satisfy them with a special path. 422 423 virtual HeapWord* allocate_new_tlab(size_t min_size, 424 size_t requested_size, 425 size_t* actual_size); 426 427 virtual HeapWord* mem_allocate(size_t word_size, 428 bool* gc_overhead_limit_was_exceeded); 429 430 // First-level mutator allocation attempt: try to allocate out of 431 // the mutator alloc region without taking the Heap_lock. This 432 // should only be used for non-humongous allocations. 433 inline HeapWord* attempt_allocation(size_t min_word_size, 434 size_t desired_word_size, 435 size_t* actual_word_size); 436 437 // Second-level mutator allocation attempt: take the Heap_lock and 438 // retry the allocation attempt, potentially scheduling a GC 439 // pause. This should only be used for non-humongous allocations. 440 HeapWord* attempt_allocation_slow(size_t word_size); 441 442 // Takes the Heap_lock and attempts a humongous allocation. It can 443 // potentially schedule a GC pause. 444 HeapWord* attempt_allocation_humongous(size_t word_size); 445 446 // Allocation attempt that should be called during safepoints (e.g., 447 // at the end of a successful GC). expect_null_mutator_alloc_region 448 // specifies whether the mutator alloc region is expected to be NULL 449 // or not. 450 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 451 bool expect_null_mutator_alloc_region); 452 453 // These methods are the "callbacks" from the G1AllocRegion class. 454 455 // For mutator alloc regions. 456 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 457 void retire_mutator_alloc_region(HeapRegion* alloc_region, 458 size_t allocated_bytes); 459 460 // For GC alloc regions. 461 bool has_more_regions(InCSetState dest); 462 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest); 463 void retire_gc_alloc_region(HeapRegion* alloc_region, 464 size_t allocated_bytes, InCSetState dest); 465 466 // - if explicit_gc is true, the GC is for a System.gc() etc, 467 // otherwise it's for a failed allocation. 468 // - if clear_all_soft_refs is true, all soft references should be 469 // cleared during the GC. 470 // - it returns false if it is unable to do the collection due to the 471 // GC locker being active, true otherwise. 472 bool do_full_collection(bool explicit_gc, 473 bool clear_all_soft_refs); 474 475 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 476 virtual void do_full_collection(bool clear_all_soft_refs); 477 478 // Callback from VM_G1CollectForAllocation operation. 479 // This function does everything necessary/possible to satisfy a 480 // failed allocation request (including collection, expansion, etc.) 481 HeapWord* satisfy_failed_allocation(size_t word_size, 482 bool* succeeded); 483 // Internal helpers used during full GC to split it up to 484 // increase readability. 485 void abort_concurrent_cycle(); 486 void verify_before_full_collection(bool explicit_gc); 487 void prepare_heap_for_full_collection(); 488 void prepare_heap_for_mutators(); 489 void abort_refinement(); 490 void verify_after_full_collection(); 491 void print_heap_after_full_collection(G1HeapTransition* heap_transition); 492 493 // Helper method for satisfy_failed_allocation() 494 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 495 bool do_gc, 496 bool clear_all_soft_refs, 497 bool expect_null_mutator_alloc_region, 498 bool* gc_succeeded); 499 500 // Attempting to expand the heap sufficiently 501 // to support an allocation of the given "word_size". If 502 // successful, perform the allocation and return the address of the 503 // allocated block, or else "NULL". 504 HeapWord* expand_and_allocate(size_t word_size); 505 506 // Process any reference objects discovered. 507 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 508 509 // If during an initial mark pause we may install a pending list head which is not 510 // otherwise reachable ensure that it is marked in the bitmap for concurrent marking 511 // to discover. 512 void make_pending_list_reachable(); 513 514 // Merges the information gathered on a per-thread basis for all worker threads 515 // during GC into global variables. 516 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states); 517 public: 518 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; } 519 520 WorkGang* workers() const { return _workers; } 521 522 G1Allocator* allocator() { 523 return _allocator; 524 } 525 526 G1HeapVerifier* verifier() { 527 return _verifier; 528 } 529 530 G1MonitoringSupport* g1mm() { 531 assert(_g1mm != NULL, "should have been initialized"); 532 return _g1mm; 533 } 534 535 void resize_heap_if_necessary(); 536 537 // Expand the garbage-first heap by at least the given size (in bytes!). 538 // Returns true if the heap was expanded by the requested amount; 539 // false otherwise. 540 // (Rounds up to a HeapRegion boundary.) 541 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL); 542 543 // Returns the PLAB statistics for a given destination. 544 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 545 546 // Determines PLAB size for a given destination. 547 inline size_t desired_plab_sz(InCSetState dest); 548 549 // Do anything common to GC's. 550 void gc_prologue(bool full); 551 void gc_epilogue(bool full); 552 553 // Does the given region fulfill remembered set based eager reclaim candidate requirements? 554 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const; 555 556 // Modify the reclaim candidate set and test for presence. 557 // These are only valid for starts_humongous regions. 558 inline void set_humongous_reclaim_candidate(uint region, bool value); 559 inline bool is_humongous_reclaim_candidate(uint region); 560 561 // Remove from the reclaim candidate set. Also remove from the 562 // collection set so that later encounters avoid the slow path. 563 inline void set_humongous_is_live(oop obj); 564 565 // Register the given region to be part of the collection set. 566 inline void register_humongous_region_with_cset(uint index); 567 // Register regions with humongous objects (actually on the start region) in 568 // the in_cset_fast_test table. 569 void register_humongous_regions_with_cset(); 570 // We register a region with the fast "in collection set" test. We 571 // simply set to true the array slot corresponding to this region. 572 void register_young_region_with_cset(HeapRegion* r) { 573 _in_cset_fast_test.set_in_young(r->hrm_index()); 574 } 575 void register_old_region_with_cset(HeapRegion* r) { 576 _in_cset_fast_test.set_in_old(r->hrm_index()); 577 } 578 void register_optional_region_with_cset(HeapRegion* r) { 579 _in_cset_fast_test.set_optional(r->hrm_index()); 580 } 581 void clear_in_cset(const HeapRegion* hr) { 582 _in_cset_fast_test.clear(hr); 583 } 584 585 void clear_cset_fast_test() { 586 _in_cset_fast_test.clear(); 587 } 588 589 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 590 591 // This is called at the start of either a concurrent cycle or a Full 592 // GC to update the number of old marking cycles started. 593 void increment_old_marking_cycles_started(); 594 595 // This is called at the end of either a concurrent cycle or a Full 596 // GC to update the number of old marking cycles completed. Those two 597 // can happen in a nested fashion, i.e., we start a concurrent 598 // cycle, a Full GC happens half-way through it which ends first, 599 // and then the cycle notices that a Full GC happened and ends 600 // too. The concurrent parameter is a boolean to help us do a bit 601 // tighter consistency checking in the method. If concurrent is 602 // false, the caller is the inner caller in the nesting (i.e., the 603 // Full GC). If concurrent is true, the caller is the outer caller 604 // in this nesting (i.e., the concurrent cycle). Further nesting is 605 // not currently supported. The end of this call also notifies 606 // the FullGCCount_lock in case a Java thread is waiting for a full 607 // GC to happen (e.g., it called System.gc() with 608 // +ExplicitGCInvokesConcurrent). 609 void increment_old_marking_cycles_completed(bool concurrent); 610 611 uint old_marking_cycles_completed() { 612 return _old_marking_cycles_completed; 613 } 614 615 G1HRPrinter* hr_printer() { return &_hr_printer; } 616 617 // Allocates a new heap region instance. 618 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 619 620 // Allocate the highest free region in the reserved heap. This will commit 621 // regions as necessary. 622 HeapRegion* alloc_highest_free_region(); 623 624 // Frees a non-humongous region by initializing its contents and 625 // adding it to the free list that's passed as a parameter (this is 626 // usually a local list which will be appended to the master free 627 // list later). The used bytes of freed regions are accumulated in 628 // pre_used. If skip_remset is true, the region's RSet will not be freed 629 // up. If skip_hot_card_cache is true, the region's hot card cache will not 630 // be freed up. The assumption is that this will be done later. 631 // The locked parameter indicates if the caller has already taken 632 // care of proper synchronization. This may allow some optimizations. 633 void free_region(HeapRegion* hr, 634 FreeRegionList* free_list, 635 bool skip_remset, 636 bool skip_hot_card_cache = false, 637 bool locked = false); 638 639 // It dirties the cards that cover the block so that the post 640 // write barrier never queues anything when updating objects on this 641 // block. It is assumed (and in fact we assert) that the block 642 // belongs to a young region. 643 inline void dirty_young_block(HeapWord* start, size_t word_size); 644 645 // Frees a humongous region by collapsing it into individual regions 646 // and calling free_region() for each of them. The freed regions 647 // will be added to the free list that's passed as a parameter (this 648 // is usually a local list which will be appended to the master free 649 // list later). 650 // The method assumes that only a single thread is ever calling 651 // this for a particular region at once. 652 void free_humongous_region(HeapRegion* hr, 653 FreeRegionList* free_list); 654 655 // Facility for allocating in 'archive' regions in high heap memory and 656 // recording the allocated ranges. These should all be called from the 657 // VM thread at safepoints, without the heap lock held. They can be used 658 // to create and archive a set of heap regions which can be mapped at the 659 // same fixed addresses in a subsequent JVM invocation. 660 void begin_archive_alloc_range(bool open = false); 661 662 // Check if the requested size would be too large for an archive allocation. 663 bool is_archive_alloc_too_large(size_t word_size); 664 665 // Allocate memory of the requested size from the archive region. This will 666 // return NULL if the size is too large or if no memory is available. It 667 // does not trigger a garbage collection. 668 HeapWord* archive_mem_allocate(size_t word_size); 669 670 // Optionally aligns the end address and returns the allocated ranges in 671 // an array of MemRegions in order of ascending addresses. 672 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 673 size_t end_alignment_in_bytes = 0); 674 675 // Facility for allocating a fixed range within the heap and marking 676 // the containing regions as 'archive'. For use at JVM init time, when the 677 // caller may mmap archived heap data at the specified range(s). 678 // Verify that the MemRegions specified in the argument array are within the 679 // reserved heap. 680 bool check_archive_addresses(MemRegion* range, size_t count); 681 682 // Commit the appropriate G1 regions containing the specified MemRegions 683 // and mark them as 'archive' regions. The regions in the array must be 684 // non-overlapping and in order of ascending address. 685 bool alloc_archive_regions(MemRegion* range, size_t count, bool open); 686 687 // Insert any required filler objects in the G1 regions around the specified 688 // ranges to make the regions parseable. This must be called after 689 // alloc_archive_regions, and after class loading has occurred. 690 void fill_archive_regions(MemRegion* range, size_t count); 691 692 // For each of the specified MemRegions, uncommit the containing G1 regions 693 // which had been allocated by alloc_archive_regions. This should be called 694 // rather than fill_archive_regions at JVM init time if the archive file 695 // mapping failed, with the same non-overlapping and sorted MemRegion array. 696 void dealloc_archive_regions(MemRegion* range, size_t count, bool is_open); 697 698 oop materialize_archived_object(oop obj); 699 700 private: 701 702 // Shrink the garbage-first heap by at most the given size (in bytes!). 703 // (Rounds down to a HeapRegion boundary.) 704 void shrink(size_t expand_bytes); 705 void shrink_helper(size_t expand_bytes); 706 707 #if TASKQUEUE_STATS 708 static void print_taskqueue_stats_hdr(outputStream* const st); 709 void print_taskqueue_stats() const; 710 void reset_taskqueue_stats(); 711 #endif // TASKQUEUE_STATS 712 713 // Schedule the VM operation that will do an evacuation pause to 714 // satisfy an allocation request of word_size. *succeeded will 715 // return whether the VM operation was successful (it did do an 716 // evacuation pause) or not (another thread beat us to it or the GC 717 // locker was active). Given that we should not be holding the 718 // Heap_lock when we enter this method, we will pass the 719 // gc_count_before (i.e., total_collections()) as a parameter since 720 // it has to be read while holding the Heap_lock. Currently, both 721 // methods that call do_collection_pause() release the Heap_lock 722 // before the call, so it's easy to read gc_count_before just before. 723 HeapWord* do_collection_pause(size_t word_size, 724 uint gc_count_before, 725 bool* succeeded, 726 GCCause::Cause gc_cause); 727 728 void wait_for_root_region_scanning(); 729 730 // The guts of the incremental collection pause, executed by the vm 731 // thread. It returns false if it is unable to do the collection due 732 // to the GC locker being active, true otherwise 733 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 734 735 G1HeapVerifier::G1VerifyType young_collection_verify_type() const; 736 void verify_before_young_collection(G1HeapVerifier::G1VerifyType type); 737 void verify_after_young_collection(G1HeapVerifier::G1VerifyType type); 738 739 void calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms); 740 741 // Actually do the work of evacuating the collection set. 742 void evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states); 743 void evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states); 744 void evacuate_optional_regions(G1ParScanThreadStateSet* per_thread_states, G1OptionalCSet* ocset); 745 746 void pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info); 747 void post_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 748 749 void expand_heap_after_young_collection(); 750 // Update object copying statistics. 751 void record_obj_copy_mem_stats(); 752 753 // The hot card cache for remembered set insertion optimization. 754 G1HotCardCache* _hot_card_cache; 755 756 // The g1 remembered set of the heap. 757 G1RemSet* _rem_set; 758 759 // A set of cards that cover the objects for which the Rsets should be updated 760 // concurrently after the collection. 761 G1DirtyCardQueueSet _dirty_card_queue_set; 762 763 // After a collection pause, convert the regions in the collection set into free 764 // regions. 765 void free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 766 767 // Abandon the current collection set without recording policy 768 // statistics or updating free lists. 769 void abandon_collection_set(G1CollectionSet* collection_set); 770 771 // The concurrent marker (and the thread it runs in.) 772 G1ConcurrentMark* _cm; 773 G1ConcurrentMarkThread* _cm_thread; 774 775 // The concurrent refiner. 776 G1ConcurrentRefine* _cr; 777 778 // The parallel task queues 779 RefToScanQueueSet *_task_queues; 780 781 // True iff a evacuation has failed in the current collection. 782 bool _evacuation_failed; 783 784 EvacuationFailedInfo* _evacuation_failed_info_array; 785 786 // Failed evacuations cause some logical from-space objects to have 787 // forwarding pointers to themselves. Reset them. 788 void remove_self_forwarding_pointers(); 789 790 // Restore the objects in the regions in the collection set after an 791 // evacuation failure. 792 void restore_after_evac_failure(); 793 794 PreservedMarksSet _preserved_marks_set; 795 796 // Preserve the mark of "obj", if necessary, in preparation for its mark 797 // word being overwritten with a self-forwarding-pointer. 798 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 799 800 #ifndef PRODUCT 801 // Support for forcing evacuation failures. Analogous to 802 // PromotionFailureALot for the other collectors. 803 804 // Records whether G1EvacuationFailureALot should be in effect 805 // for the current GC 806 bool _evacuation_failure_alot_for_current_gc; 807 808 // Used to record the GC number for interval checking when 809 // determining whether G1EvaucationFailureALot is in effect 810 // for the current GC. 811 size_t _evacuation_failure_alot_gc_number; 812 813 // Count of the number of evacuations between failures. 814 volatile size_t _evacuation_failure_alot_count; 815 816 // Set whether G1EvacuationFailureALot should be in effect 817 // for the current GC (based upon the type of GC and which 818 // command line flags are set); 819 inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc, 820 bool during_initial_mark, 821 bool mark_or_rebuild_in_progress); 822 823 inline void set_evacuation_failure_alot_for_current_gc(); 824 825 // Return true if it's time to cause an evacuation failure. 826 inline bool evacuation_should_fail(); 827 828 // Reset the G1EvacuationFailureALot counters. Should be called at 829 // the end of an evacuation pause in which an evacuation failure occurred. 830 inline void reset_evacuation_should_fail(); 831 #endif // !PRODUCT 832 833 // ("Weak") Reference processing support. 834 // 835 // G1 has 2 instances of the reference processor class. One 836 // (_ref_processor_cm) handles reference object discovery 837 // and subsequent processing during concurrent marking cycles. 838 // 839 // The other (_ref_processor_stw) handles reference object 840 // discovery and processing during full GCs and incremental 841 // evacuation pauses. 842 // 843 // During an incremental pause, reference discovery will be 844 // temporarily disabled for _ref_processor_cm and will be 845 // enabled for _ref_processor_stw. At the end of the evacuation 846 // pause references discovered by _ref_processor_stw will be 847 // processed and discovery will be disabled. The previous 848 // setting for reference object discovery for _ref_processor_cm 849 // will be re-instated. 850 // 851 // At the start of marking: 852 // * Discovery by the CM ref processor is verified to be inactive 853 // and it's discovered lists are empty. 854 // * Discovery by the CM ref processor is then enabled. 855 // 856 // At the end of marking: 857 // * Any references on the CM ref processor's discovered 858 // lists are processed (possibly MT). 859 // 860 // At the start of full GC we: 861 // * Disable discovery by the CM ref processor and 862 // empty CM ref processor's discovered lists 863 // (without processing any entries). 864 // * Verify that the STW ref processor is inactive and it's 865 // discovered lists are empty. 866 // * Temporarily set STW ref processor discovery as single threaded. 867 // * Temporarily clear the STW ref processor's _is_alive_non_header 868 // field. 869 // * Finally enable discovery by the STW ref processor. 870 // 871 // The STW ref processor is used to record any discovered 872 // references during the full GC. 873 // 874 // At the end of a full GC we: 875 // * Enqueue any reference objects discovered by the STW ref processor 876 // that have non-live referents. This has the side-effect of 877 // making the STW ref processor inactive by disabling discovery. 878 // * Verify that the CM ref processor is still inactive 879 // and no references have been placed on it's discovered 880 // lists (also checked as a precondition during initial marking). 881 882 // The (stw) reference processor... 883 ReferenceProcessor* _ref_processor_stw; 884 885 // During reference object discovery, the _is_alive_non_header 886 // closure (if non-null) is applied to the referent object to 887 // determine whether the referent is live. If so then the 888 // reference object does not need to be 'discovered' and can 889 // be treated as a regular oop. This has the benefit of reducing 890 // the number of 'discovered' reference objects that need to 891 // be processed. 892 // 893 // Instance of the is_alive closure for embedding into the 894 // STW reference processor as the _is_alive_non_header field. 895 // Supplying a value for the _is_alive_non_header field is 896 // optional but doing so prevents unnecessary additions to 897 // the discovered lists during reference discovery. 898 G1STWIsAliveClosure _is_alive_closure_stw; 899 900 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw; 901 902 // The (concurrent marking) reference processor... 903 ReferenceProcessor* _ref_processor_cm; 904 905 // Instance of the concurrent mark is_alive closure for embedding 906 // into the Concurrent Marking reference processor as the 907 // _is_alive_non_header field. Supplying a value for the 908 // _is_alive_non_header field is optional but doing so prevents 909 // unnecessary additions to the discovered lists during reference 910 // discovery. 911 G1CMIsAliveClosure _is_alive_closure_cm; 912 913 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm; 914 public: 915 916 RefToScanQueue *task_queue(uint i) const; 917 918 uint num_task_queues() const; 919 920 // A set of cards where updates happened during the GC 921 G1DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 922 923 // Create a G1CollectedHeap with the specified policy. 924 // Must call the initialize method afterwards. 925 // May not return if something goes wrong. 926 G1CollectedHeap(G1CollectorPolicy* policy); 927 928 private: 929 jint initialize_concurrent_refinement(); 930 jint initialize_young_gen_sampling_thread(); 931 public: 932 // Initialize the G1CollectedHeap to have the initial and 933 // maximum sizes and remembered and barrier sets 934 // specified by the policy object. 935 jint initialize(); 936 937 virtual void stop(); 938 virtual void safepoint_synchronize_begin(); 939 virtual void safepoint_synchronize_end(); 940 941 // Return the (conservative) maximum heap alignment for any G1 heap 942 static size_t conservative_max_heap_alignment(); 943 944 // Does operations required after initialization has been done. 945 void post_initialize(); 946 947 // Initialize weak reference processing. 948 void ref_processing_init(); 949 950 virtual Name kind() const { 951 return CollectedHeap::G1; 952 } 953 954 virtual const char* name() const { 955 return "G1"; 956 } 957 958 const G1CollectorState* collector_state() const { return &_collector_state; } 959 G1CollectorState* collector_state() { return &_collector_state; } 960 961 // The current policy object for the collector. 962 G1Policy* policy() const { return _policy; } 963 // The remembered set. 964 G1RemSet* rem_set() const { return _rem_set; } 965 966 inline G1GCPhaseTimes* phase_times() const; 967 968 HeapRegionManager* hrm() const { return _hrm; } 969 970 const G1CollectionSet* collection_set() const { return &_collection_set; } 971 G1CollectionSet* collection_set() { return &_collection_set; } 972 973 virtual CollectorPolicy* collector_policy() const; 974 975 virtual SoftRefPolicy* soft_ref_policy(); 976 977 virtual void initialize_serviceability(); 978 virtual MemoryUsage memory_usage(); 979 virtual GrowableArray<GCMemoryManager*> memory_managers(); 980 virtual GrowableArray<MemoryPool*> memory_pools(); 981 982 // Try to minimize the remembered set. 983 void scrub_rem_set(); 984 985 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 986 void iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_i); 987 988 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. 989 void iterate_dirty_card_closure(G1CardTableEntryClosure* cl, uint worker_i); 990 991 // The shared block offset table array. 992 G1BlockOffsetTable* bot() const { return _bot; } 993 994 // Reference Processing accessors 995 996 // The STW reference processor.... 997 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 998 999 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1000 1001 // The Concurrent Marking reference processor... 1002 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1003 1004 size_t unused_committed_regions_in_bytes() const; 1005 virtual size_t capacity() const; 1006 virtual size_t used() const; 1007 // This should be called when we're not holding the heap lock. The 1008 // result might be a bit inaccurate. 1009 size_t used_unlocked() const; 1010 size_t recalculate_used() const; 1011 1012 // These virtual functions do the actual allocation. 1013 // Some heaps may offer a contiguous region for shared non-blocking 1014 // allocation, via inlined code (by exporting the address of the top and 1015 // end fields defining the extent of the contiguous allocation region.) 1016 // But G1CollectedHeap doesn't yet support this. 1017 1018 virtual bool is_maximal_no_gc() const { 1019 return _hrm->available() == 0; 1020 } 1021 1022 // Returns whether there are any regions left in the heap for allocation. 1023 bool has_regions_left_for_allocation() const { 1024 return !is_maximal_no_gc() || num_free_regions() != 0; 1025 } 1026 1027 // The current number of regions in the heap. 1028 uint num_regions() const { return _hrm->length(); } 1029 1030 // The max number of regions in the heap. 1031 uint max_regions() const { return _hrm->max_length(); } 1032 1033 // Max number of regions that can be comitted. 1034 uint max_expandable_regions() const { return _hrm->max_expandable_length(); } 1035 1036 // The number of regions that are completely free. 1037 uint num_free_regions() const { return _hrm->num_free_regions(); } 1038 1039 // The number of regions that can be allocated into. 1040 uint num_free_or_available_regions() const { return num_free_regions() + _hrm->available(); } 1041 1042 MemoryUsage get_auxiliary_data_memory_usage() const { 1043 return _hrm->get_auxiliary_data_memory_usage(); 1044 } 1045 1046 // The number of regions that are not completely free. 1047 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1048 1049 #ifdef ASSERT 1050 bool is_on_master_free_list(HeapRegion* hr) { 1051 return _hrm->is_free(hr); 1052 } 1053 #endif // ASSERT 1054 1055 inline void old_set_add(HeapRegion* hr); 1056 inline void old_set_remove(HeapRegion* hr); 1057 1058 inline void archive_set_add(HeapRegion* hr); 1059 1060 size_t non_young_capacity_bytes() { 1061 return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes; 1062 } 1063 1064 // Determine whether the given region is one that we are using as an 1065 // old GC alloc region. 1066 bool is_old_gc_alloc_region(HeapRegion* hr); 1067 1068 // Perform a collection of the heap; intended for use in implementing 1069 // "System.gc". This probably implies as full a collection as the 1070 // "CollectedHeap" supports. 1071 virtual void collect(GCCause::Cause cause); 1072 1073 // Perform a collection of the heap with the given cause; if the VM operation 1074 // fails to execute for any reason, retry only if retry_on_gc_failure is set. 1075 // Returns whether this collection actually executed. 1076 bool try_collect(GCCause::Cause cause, bool retry_on_gc_failure); 1077 1078 // True iff an evacuation has failed in the most-recent collection. 1079 bool evacuation_failed() { return _evacuation_failed; } 1080 1081 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed); 1082 void prepend_to_freelist(FreeRegionList* list); 1083 void decrement_summary_bytes(size_t bytes); 1084 1085 virtual bool is_in(const void* p) const; 1086 #ifdef ASSERT 1087 // Returns whether p is in one of the available areas of the heap. Slow but 1088 // extensive version. 1089 bool is_in_exact(const void* p) const; 1090 #endif 1091 1092 // Return "TRUE" iff the given object address is within the collection 1093 // set. Assumes that the reference points into the heap. 1094 inline bool is_in_cset(const HeapRegion *hr); 1095 inline bool is_in_cset(oop obj); 1096 inline bool is_in_cset(HeapWord* addr); 1097 1098 inline bool is_in_cset_or_humongous(const oop obj); 1099 1100 private: 1101 // This array is used for a quick test on whether a reference points into 1102 // the collection set or not. Each of the array's elements denotes whether the 1103 // corresponding region is in the collection set or not. 1104 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1105 1106 public: 1107 1108 inline InCSetState in_cset_state(const oop obj); 1109 1110 // Return "TRUE" iff the given object address is in the reserved 1111 // region of g1. 1112 bool is_in_g1_reserved(const void* p) const { 1113 return _hrm->reserved().contains(p); 1114 } 1115 1116 // Returns a MemRegion that corresponds to the space that has been 1117 // reserved for the heap 1118 MemRegion g1_reserved() const { 1119 return _hrm->reserved(); 1120 } 1121 1122 virtual bool is_in_closed_subset(const void* p) const; 1123 1124 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; } 1125 1126 G1CardTable* card_table() const { 1127 return _card_table; 1128 } 1129 1130 // Iteration functions. 1131 1132 // Iterate over all objects, calling "cl.do_object" on each. 1133 virtual void object_iterate(ObjectClosure* cl); 1134 1135 virtual void safe_object_iterate(ObjectClosure* cl) { 1136 object_iterate(cl); 1137 } 1138 1139 // Iterate over heap regions, in address order, terminating the 1140 // iteration early if the "do_heap_region" method returns "true". 1141 void heap_region_iterate(HeapRegionClosure* blk) const; 1142 1143 // Return the region with the given index. It assumes the index is valid. 1144 inline HeapRegion* region_at(uint index) const; 1145 inline HeapRegion* region_at_or_null(uint index) const; 1146 1147 // Return the next region (by index) that is part of the same 1148 // humongous object that hr is part of. 1149 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1150 1151 // Calculate the region index of the given address. Given address must be 1152 // within the heap. 1153 inline uint addr_to_region(HeapWord* addr) const; 1154 1155 inline HeapWord* bottom_addr_for_region(uint index) const; 1156 1157 // Two functions to iterate over the heap regions in parallel. Threads 1158 // compete using the HeapRegionClaimer to claim the regions before 1159 // applying the closure on them. 1160 // The _from_worker_offset version uses the HeapRegionClaimer and 1161 // the worker id to calculate a start offset to prevent all workers to 1162 // start from the point. 1163 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 1164 HeapRegionClaimer* hrclaimer, 1165 uint worker_id) const; 1166 1167 void heap_region_par_iterate_from_start(HeapRegionClosure* cl, 1168 HeapRegionClaimer* hrclaimer) const; 1169 1170 // Iterate over the regions (if any) in the current collection set. 1171 void collection_set_iterate(HeapRegionClosure* blk); 1172 1173 // Iterate over the regions (if any) in the current collection set. Starts the 1174 // iteration over the entire collection set so that the start regions of a given 1175 // worker id over the set active_workers are evenly spread across the set of 1176 // collection set regions. 1177 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id); 1178 1179 // Returns the HeapRegion that contains addr. addr must not be NULL. 1180 template <class T> 1181 inline HeapRegion* heap_region_containing(const T addr) const; 1182 1183 // Returns the HeapRegion that contains addr, or NULL if that is an uncommitted 1184 // region. addr must not be NULL. 1185 template <class T> 1186 inline HeapRegion* heap_region_containing_or_null(const T addr) const; 1187 1188 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1189 // each address in the (reserved) heap is a member of exactly 1190 // one block. The defining characteristic of a block is that it is 1191 // possible to find its size, and thus to progress forward to the next 1192 // block. (Blocks may be of different sizes.) Thus, blocks may 1193 // represent Java objects, or they might be free blocks in a 1194 // free-list-based heap (or subheap), as long as the two kinds are 1195 // distinguishable and the size of each is determinable. 1196 1197 // Returns the address of the start of the "block" that contains the 1198 // address "addr". We say "blocks" instead of "object" since some heaps 1199 // may not pack objects densely; a chunk may either be an object or a 1200 // non-object. 1201 virtual HeapWord* block_start(const void* addr) const; 1202 1203 // Requires "addr" to be the start of a chunk, and returns its size. 1204 // "addr + size" is required to be the start of a new chunk, or the end 1205 // of the active area of the heap. 1206 virtual size_t block_size(const HeapWord* addr) const; 1207 1208 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1209 // the block is an object. 1210 virtual bool block_is_obj(const HeapWord* addr) const; 1211 1212 // Section on thread-local allocation buffers (TLABs) 1213 // See CollectedHeap for semantics. 1214 1215 bool supports_tlab_allocation() const; 1216 size_t tlab_capacity(Thread* ignored) const; 1217 size_t tlab_used(Thread* ignored) const; 1218 size_t max_tlab_size() const; 1219 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1220 1221 inline bool is_in_young(const oop obj); 1222 1223 // Returns "true" iff the given word_size is "very large". 1224 static bool is_humongous(size_t word_size) { 1225 // Note this has to be strictly greater-than as the TLABs 1226 // are capped at the humongous threshold and we want to 1227 // ensure that we don't try to allocate a TLAB as 1228 // humongous and that we don't allocate a humongous 1229 // object in a TLAB. 1230 return word_size > _humongous_object_threshold_in_words; 1231 } 1232 1233 // Returns the humongous threshold for a specific region size 1234 static size_t humongous_threshold_for(size_t region_size) { 1235 return (region_size / 2); 1236 } 1237 1238 // Returns the number of regions the humongous object of the given word size 1239 // requires. 1240 static size_t humongous_obj_size_in_regions(size_t word_size); 1241 1242 // Print the maximum heap capacity. 1243 virtual size_t max_capacity() const; 1244 1245 // Return the size of reserved memory. Returns different value than max_capacity() when AllocateOldGenAt is used. 1246 virtual size_t max_reserved_capacity() const; 1247 1248 virtual jlong millis_since_last_gc(); 1249 1250 1251 // Convenience function to be used in situations where the heap type can be 1252 // asserted to be this type. 1253 static G1CollectedHeap* heap(); 1254 1255 void set_region_short_lived_locked(HeapRegion* hr); 1256 // add appropriate methods for any other surv rate groups 1257 1258 const G1SurvivorRegions* survivor() const { return &_survivor; } 1259 1260 uint eden_regions_count() const { return _eden.length(); } 1261 uint survivor_regions_count() const { return _survivor.length(); } 1262 uint young_regions_count() const { return _eden.length() + _survivor.length(); } 1263 uint old_regions_count() const { return _old_set.length(); } 1264 uint archive_regions_count() const { return _archive_set.length(); } 1265 uint humongous_regions_count() const { return _humongous_set.length(); } 1266 1267 #ifdef ASSERT 1268 bool check_young_list_empty(); 1269 #endif 1270 1271 // *** Stuff related to concurrent marking. It's not clear to me that so 1272 // many of these need to be public. 1273 1274 // The functions below are helper functions that a subclass of 1275 // "CollectedHeap" can use in the implementation of its virtual 1276 // functions. 1277 // This performs a concurrent marking of the live objects in a 1278 // bitmap off to the side. 1279 void do_concurrent_mark(); 1280 1281 bool is_marked_next(oop obj) const; 1282 1283 // Determine if an object is dead, given the object and also 1284 // the region to which the object belongs. An object is dead 1285 // iff a) it was not allocated since the last mark, b) it 1286 // is not marked, and c) it is not in an archive region. 1287 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1288 return 1289 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) && 1290 !hr->is_archive(); 1291 } 1292 1293 // This function returns true when an object has been 1294 // around since the previous marking and hasn't yet 1295 // been marked during this marking, and is not in an archive region. 1296 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1297 return 1298 !hr->obj_allocated_since_next_marking(obj) && 1299 !is_marked_next(obj) && 1300 !hr->is_archive(); 1301 } 1302 1303 // Determine if an object is dead, given only the object itself. 1304 // This will find the region to which the object belongs and 1305 // then call the region version of the same function. 1306 1307 // Added if it is NULL it isn't dead. 1308 1309 inline bool is_obj_dead(const oop obj) const; 1310 1311 inline bool is_obj_ill(const oop obj) const; 1312 1313 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const; 1314 inline bool is_obj_dead_full(const oop obj) const; 1315 1316 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1317 1318 // Refinement 1319 1320 G1ConcurrentRefine* concurrent_refine() const { return _cr; } 1321 1322 // Optimized nmethod scanning support routines 1323 1324 // Is an oop scavengeable 1325 virtual bool is_scavengable(oop obj); 1326 1327 // Register the given nmethod with the G1 heap. 1328 virtual void register_nmethod(nmethod* nm); 1329 1330 // Unregister the given nmethod from the G1 heap. 1331 virtual void unregister_nmethod(nmethod* nm); 1332 1333 // Free up superfluous code root memory. 1334 void purge_code_root_memory(); 1335 1336 // Rebuild the strong code root lists for each region 1337 // after a full GC. 1338 void rebuild_strong_code_roots(); 1339 1340 // Partial cleaning of VM internal data structures. 1341 void string_dedup_cleaning(BoolObjectClosure* is_alive, 1342 OopClosure* keep_alive, 1343 G1GCPhaseTimes* phase_times = NULL); 1344 1345 // Performs cleaning of data structures after class unloading. 1346 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); 1347 1348 // Redirty logged cards in the refinement queue. 1349 void redirty_logged_cards(); 1350 // Verification 1351 1352 // Deduplicate the string 1353 virtual void deduplicate_string(oop str); 1354 1355 // Perform any cleanup actions necessary before allowing a verification. 1356 virtual void prepare_for_verify(); 1357 1358 // Perform verification. 1359 1360 // vo == UsePrevMarking -> use "prev" marking information, 1361 // vo == UseNextMarking -> use "next" marking information 1362 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS 1363 // 1364 // NOTE: Only the "prev" marking information is guaranteed to be 1365 // consistent most of the time, so most calls to this should use 1366 // vo == UsePrevMarking. 1367 // Currently, there is only one case where this is called with 1368 // vo == UseNextMarking, which is to verify the "next" marking 1369 // information at the end of remark. 1370 // Currently there is only one place where this is called with 1371 // vo == UseFullMarking, which is to verify the marking during a 1372 // full GC. 1373 void verify(VerifyOption vo); 1374 1375 // WhiteBox testing support. 1376 virtual bool supports_concurrent_phase_control() const; 1377 virtual bool request_concurrent_phase(const char* phase); 1378 bool is_heterogeneous_heap() const; 1379 1380 virtual WorkGang* get_safepoint_workers() { return _workers; } 1381 1382 // The methods below are here for convenience and dispatch the 1383 // appropriate method depending on value of the given VerifyOption 1384 // parameter. The values for that parameter, and their meanings, 1385 // are the same as those above. 1386 1387 bool is_obj_dead_cond(const oop obj, 1388 const HeapRegion* hr, 1389 const VerifyOption vo) const; 1390 1391 bool is_obj_dead_cond(const oop obj, 1392 const VerifyOption vo) const; 1393 1394 G1HeapSummary create_g1_heap_summary(); 1395 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1396 1397 // Printing 1398 private: 1399 void print_heap_regions() const; 1400 void print_regions_on(outputStream* st) const; 1401 1402 public: 1403 virtual void print_on(outputStream* st) const; 1404 virtual void print_extended_on(outputStream* st) const; 1405 virtual void print_on_error(outputStream* st) const; 1406 1407 virtual void print_gc_threads_on(outputStream* st) const; 1408 virtual void gc_threads_do(ThreadClosure* tc) const; 1409 1410 // Override 1411 void print_tracing_info() const; 1412 1413 // The following two methods are helpful for debugging RSet issues. 1414 void print_cset_rsets() PRODUCT_RETURN; 1415 void print_all_rsets() PRODUCT_RETURN; 1416 1417 size_t pending_card_num(); 1418 }; 1419 1420 class G1ParEvacuateFollowersClosure : public VoidClosure { 1421 private: 1422 double _start_term; 1423 double _term_time; 1424 size_t _term_attempts; 1425 1426 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 1427 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 1428 protected: 1429 G1CollectedHeap* _g1h; 1430 G1ParScanThreadState* _par_scan_state; 1431 RefToScanQueueSet* _queues; 1432 ParallelTaskTerminator* _terminator; 1433 G1GCPhaseTimes::GCParPhases _phase; 1434 1435 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 1436 RefToScanQueueSet* queues() { return _queues; } 1437 ParallelTaskTerminator* terminator() { return _terminator; } 1438 1439 public: 1440 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 1441 G1ParScanThreadState* par_scan_state, 1442 RefToScanQueueSet* queues, 1443 ParallelTaskTerminator* terminator, 1444 G1GCPhaseTimes::GCParPhases phase) 1445 : _start_term(0.0), _term_time(0.0), _term_attempts(0), 1446 _g1h(g1h), _par_scan_state(par_scan_state), 1447 _queues(queues), _terminator(terminator), _phase(phase) {} 1448 1449 void do_void(); 1450 1451 double term_time() const { return _term_time; } 1452 size_t term_attempts() const { return _term_attempts; } 1453 1454 private: 1455 inline bool offer_termination(); 1456 }; 1457 1458 #endif // SHARE_GC_G1_G1COLLECTEDHEAP_HPP