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