1 /* 2 * Copyright (c) 2001, 2018, 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_VM_GC_G1_G1COLLECTEDHEAP_HPP 26 #define SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP 27 28 #include "gc/g1/evacuationInfo.hpp" 29 #include "gc/g1/g1BarrierSet.hpp" 30 #include "gc/g1/g1BiasedArray.hpp" 31 #include "gc/g1/g1CardTable.hpp" 32 #include "gc/g1/g1CollectionSet.hpp" 33 #include "gc/g1/g1CollectorState.hpp" 34 #include "gc/g1/g1ConcurrentMark.hpp" 35 #include "gc/g1/g1EdenRegions.hpp" 36 #include "gc/g1/g1EvacFailure.hpp" 37 #include "gc/g1/g1EvacStats.hpp" 38 #include "gc/g1/g1HeapTransition.hpp" 39 #include "gc/g1/g1HeapVerifier.hpp" 40 #include "gc/g1/g1HRPrinter.hpp" 41 #include "gc/g1/g1InCSetState.hpp" 42 #include "gc/g1/g1MonitoringSupport.hpp" 43 #include "gc/g1/g1SurvivorRegions.hpp" 44 #include "gc/g1/g1YCTypes.hpp" 45 #include "gc/g1/heapRegionManager.hpp" 46 #include "gc/g1/heapRegionManagerForHeteroHeap.hpp" 47 #include "gc/g1/heapRegionSet.hpp" 48 #include "gc/shared/barrierSet.hpp" 49 #include "gc/shared/collectedHeap.hpp" 50 #include "gc/shared/gcHeapSummary.hpp" 51 #include "gc/shared/plab.hpp" 52 #include "gc/shared/preservedMarks.hpp" 53 #include "gc/shared/softRefPolicy.hpp" 54 #include "memory/memRegion.hpp" 55 #include "utilities/stack.hpp" 56 57 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 58 // It uses the "Garbage First" heap organization and algorithm, which 59 // may combine concurrent marking with parallel, incremental compaction of 60 // heap subsets that will yield large amounts of garbage. 61 62 // Forward declarations 63 class HeapRegion; 64 class HRRSCleanupTask; 65 class GenerationSpec; 66 class G1ParScanThreadState; 67 class G1ParScanThreadStateSet; 68 class G1ParScanThreadState; 69 class MemoryPool; 70 class MemoryManager; 71 class ObjectClosure; 72 class SpaceClosure; 73 class CompactibleSpaceClosure; 74 class Space; 75 class G1CollectionSet; 76 class G1CollectorPolicy; 77 class G1Policy; 78 class G1HotCardCache; 79 class G1RemSet; 80 class G1YoungRemSetSamplingThread; 81 class HeapRegionRemSetIterator; 82 class G1ConcurrentMark; 83 class G1ConcurrentMarkThread; 84 class G1ConcurrentRefine; 85 class GenerationCounters; 86 class STWGCTimer; 87 class G1NewTracer; 88 class EvacuationFailedInfo; 89 class nmethod; 90 class WorkGang; 91 class G1Allocator; 92 class G1ArchiveAllocator; 93 class G1FullGCScope; 94 class G1HeapVerifier; 95 class G1HeapSizingPolicy; 96 class G1HeapSummary; 97 class G1EvacSummary; 98 99 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 100 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 101 102 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 103 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 104 105 // The G1 STW is alive closure. 106 // An instance is embedded into the G1CH and used as the 107 // (optional) _is_alive_non_header closure in the STW 108 // reference processor. It is also extensively used during 109 // reference processing during STW evacuation pauses. 110 class G1STWIsAliveClosure : public BoolObjectClosure { 111 G1CollectedHeap* _g1h; 112 public: 113 G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {} 114 bool do_object_b(oop p); 115 }; 116 117 class G1STWSubjectToDiscoveryClosure : public BoolObjectClosure { 118 G1CollectedHeap* _g1h; 119 public: 120 G1STWSubjectToDiscoveryClosure(G1CollectedHeap* g1h) : _g1h(g1h) {} 121 bool do_object_b(oop p); 122 }; 123 124 class G1RegionMappingChangedListener : public G1MappingChangedListener { 125 private: 126 void reset_from_card_cache(uint start_idx, size_t num_regions); 127 public: 128 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 129 }; 130 131 class G1CollectedHeap : public CollectedHeap { 132 friend class G1FreeCollectionSetTask; 133 friend class VM_CollectForMetadataAllocation; 134 friend class VM_G1CollectForAllocation; 135 friend class VM_G1CollectFull; 136 friend class VMStructs; 137 friend class MutatorAllocRegion; 138 friend class G1FullCollector; 139 friend class G1GCAllocRegion; 140 friend class G1HeapVerifier; 141 142 // Closures used in implementation. 143 friend class G1ParScanThreadState; 144 friend class G1ParScanThreadStateSet; 145 friend class G1ParTask; 146 friend class G1PLABAllocator; 147 friend class G1PrepareCompactClosure; 148 149 // Other related classes. 150 friend class HeapRegionClaimer; 151 152 // Testing classes. 153 friend class G1CheckCSetFastTableClosure; 154 155 private: 156 G1YoungRemSetSamplingThread* _young_gen_sampling_thread; 157 158 WorkGang* _workers; 159 G1CollectorPolicy* _collector_policy; 160 G1CardTable* _card_table; 161 162 SoftRefPolicy _soft_ref_policy; 163 164 static size_t _humongous_object_threshold_in_words; 165 166 // These sets keep track of old, archive and humongous regions respectively. 167 HeapRegionSet _old_set; 168 HeapRegionSet _archive_set; 169 HeapRegionSet _humongous_set; 170 171 void eagerly_reclaim_humongous_regions(); 172 // Start a new incremental collection set for the next pause. 173 void start_new_collection_set(); 174 175 // The block offset table for the G1 heap. 176 G1BlockOffsetTable* _bot; 177 178 // Tears down the region sets / lists so that they are empty and the 179 // regions on the heap do not belong to a region set / list. The 180 // only exception is the humongous set which we leave unaltered. If 181 // free_list_only is true, it will only tear down the master free 182 // list. It is called before a Full GC (free_list_only == false) or 183 // before heap shrinking (free_list_only == true). 184 void tear_down_region_sets(bool free_list_only); 185 186 // Rebuilds the region sets / lists so that they are repopulated to 187 // reflect the contents of the heap. The only exception is the 188 // humongous set which was not torn down in the first place. If 189 // free_list_only is true, it will only rebuild the master free 190 // list. It is called after a Full GC (free_list_only == false) or 191 // after heap shrinking (free_list_only == true). 192 void rebuild_region_sets(bool free_list_only); 193 194 // Callback for region mapping changed events. 195 G1RegionMappingChangedListener _listener; 196 197 // The sequence of all heap regions in the heap. 198 HeapRegionManager* _hrm; 199 200 // is the heap on heterogenous memory? 201 bool _is_hetero_heap; 202 203 // Manages all allocations with regions except humongous object allocations. 204 G1Allocator* _allocator; 205 206 // Manages all heap verification. 207 G1HeapVerifier* _verifier; 208 209 // Outside of GC pauses, the number of bytes used in all regions other 210 // than the current allocation region(s). 211 size_t _summary_bytes_used; 212 213 void increase_used(size_t bytes); 214 void decrease_used(size_t bytes); 215 216 void set_used(size_t bytes); 217 218 // Class that handles archive allocation ranges. 219 G1ArchiveAllocator* _archive_allocator; 220 221 // GC allocation statistics policy for survivors. 222 G1EvacStats _survivor_evac_stats; 223 224 // GC allocation statistics policy for tenured objects. 225 G1EvacStats _old_evac_stats; 226 227 // It specifies whether we should attempt to expand the heap after a 228 // region allocation failure. If heap expansion fails we set this to 229 // false so that we don't re-attempt the heap expansion (it's likely 230 // that subsequent expansion attempts will also fail if one fails). 231 // Currently, it is only consulted during GC and it's reset at the 232 // start of each GC. 233 bool _expand_heap_after_alloc_failure; 234 235 // Helper for monitoring and management support. 236 G1MonitoringSupport* _g1mm; 237 238 // Records whether the region at the given index is (still) a 239 // candidate for eager reclaim. Only valid for humongous start 240 // regions; other regions have unspecified values. Humongous start 241 // regions are initialized at start of collection pause, with 242 // candidates removed from the set as they are found reachable from 243 // roots or the young generation. 244 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 245 protected: 246 bool default_value() const { return false; } 247 public: 248 void clear() { G1BiasedMappedArray<bool>::clear(); } 249 void set_candidate(uint region, bool value) { 250 set_by_index(region, value); 251 } 252 bool is_candidate(uint region) { 253 return get_by_index(region); 254 } 255 }; 256 257 HumongousReclaimCandidates _humongous_reclaim_candidates; 258 // Stores whether during humongous object registration we found candidate regions. 259 // If not, we can skip a few steps. 260 bool _has_humongous_reclaim_candidates; 261 262 G1HRPrinter _hr_printer; 263 264 // It decides whether an explicit GC should start a concurrent cycle 265 // instead of doing a STW GC. Currently, a concurrent cycle is 266 // explicitly started if: 267 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 268 // (b) cause == _g1_humongous_allocation 269 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 270 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 271 // (e) cause == _wb_conc_mark 272 bool should_do_concurrent_full_gc(GCCause::Cause cause); 273 274 // indicates whether we are in young or mixed GC mode 275 G1CollectorState _collector_state; 276 277 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 278 // concurrent cycles) we have started. 279 volatile uint _old_marking_cycles_started; 280 281 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 282 // concurrent cycles) we have completed. 283 volatile uint _old_marking_cycles_completed; 284 285 // This is a non-product method that is helpful for testing. It is 286 // called at the end of a GC and artificially expands the heap by 287 // allocating a number of dead regions. This way we can induce very 288 // frequent marking cycles and stress the cleanup / concurrent 289 // cleanup code more (as all the regions that will be allocated by 290 // this method will be found dead by the marking cycle). 291 void allocate_dummy_regions() PRODUCT_RETURN; 292 293 // If the HR printer is active, dump the state of the regions in the 294 // heap after a compaction. 295 void print_hrm_post_compaction(); 296 297 // Create a memory mapper for auxiliary data structures of the given size and 298 // translation factor. 299 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 300 size_t size, 301 size_t translation_factor); 302 303 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 304 305 // These are macros so that, if the assert fires, we get the correct 306 // line number, file, etc. 307 308 #define heap_locking_asserts_params(_extra_message_) \ 309 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 310 (_extra_message_), \ 311 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 312 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 313 BOOL_TO_STR(Thread::current()->is_VM_thread()) 314 315 #define assert_heap_locked() \ 316 do { \ 317 assert(Heap_lock->owned_by_self(), \ 318 heap_locking_asserts_params("should be holding the Heap_lock")); \ 319 } while (0) 320 321 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 322 do { \ 323 assert(Heap_lock->owned_by_self() || \ 324 (SafepointSynchronize::is_at_safepoint() && \ 325 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 326 heap_locking_asserts_params("should be holding the Heap_lock or " \ 327 "should be at a safepoint")); \ 328 } while (0) 329 330 #define assert_heap_locked_and_not_at_safepoint() \ 331 do { \ 332 assert(Heap_lock->owned_by_self() && \ 333 !SafepointSynchronize::is_at_safepoint(), \ 334 heap_locking_asserts_params("should be holding the Heap_lock and " \ 335 "should not be at a safepoint")); \ 336 } while (0) 337 338 #define assert_heap_not_locked() \ 339 do { \ 340 assert(!Heap_lock->owned_by_self(), \ 341 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 342 } while (0) 343 344 #define assert_heap_not_locked_and_not_at_safepoint() \ 345 do { \ 346 assert(!Heap_lock->owned_by_self() && \ 347 !SafepointSynchronize::is_at_safepoint(), \ 348 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 349 "should not be at a safepoint")); \ 350 } while (0) 351 352 #define assert_at_safepoint_on_vm_thread() \ 353 do { \ 354 assert_at_safepoint(); \ 355 assert(Thread::current_or_null() != NULL, "no current thread"); \ 356 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \ 357 } while (0) 358 359 // The young region list. 360 G1EdenRegions _eden; 361 G1SurvivorRegions _survivor; 362 363 STWGCTimer* _gc_timer_stw; 364 365 G1NewTracer* _gc_tracer_stw; 366 367 // The current policy object for the collector. 368 G1Policy* _g1_policy; 369 G1HeapSizingPolicy* _heap_sizing_policy; 370 371 G1CollectionSet _collection_set; 372 373 // Try to allocate a single non-humongous HeapRegion sufficient for 374 // an allocation of the given word_size. If do_expand is true, 375 // attempt to expand the heap if necessary to satisfy the allocation 376 // request. If the region is to be used as an old region or for a 377 // humongous object, set is_old to true. If not, to false. 378 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 379 380 // Initialize a contiguous set of free regions of length num_regions 381 // and starting at index first so that they appear as a single 382 // humongous region. 383 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 384 uint num_regions, 385 size_t word_size); 386 387 // Attempt to allocate a humongous object of the given size. Return 388 // NULL if unsuccessful. 389 HeapWord* humongous_obj_allocate(size_t word_size); 390 391 // The following two methods, allocate_new_tlab() and 392 // mem_allocate(), are the two main entry points from the runtime 393 // into the G1's allocation routines. They have the following 394 // assumptions: 395 // 396 // * They should both be called outside safepoints. 397 // 398 // * They should both be called without holding the Heap_lock. 399 // 400 // * All allocation requests for new TLABs should go to 401 // allocate_new_tlab(). 402 // 403 // * All non-TLAB allocation requests should go to mem_allocate(). 404 // 405 // * If either call cannot satisfy the allocation request using the 406 // current allocating region, they will try to get a new one. If 407 // this fails, they will attempt to do an evacuation pause and 408 // retry the allocation. 409 // 410 // * If all allocation attempts fail, even after trying to schedule 411 // an evacuation pause, allocate_new_tlab() will return NULL, 412 // whereas mem_allocate() will attempt a heap expansion and/or 413 // schedule a Full GC. 414 // 415 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 416 // should never be called with word_size being humongous. All 417 // humongous allocation requests should go to mem_allocate() which 418 // will satisfy them with a special path. 419 420 virtual HeapWord* allocate_new_tlab(size_t min_size, 421 size_t requested_size, 422 size_t* actual_size); 423 424 virtual HeapWord* mem_allocate(size_t word_size, 425 bool* gc_overhead_limit_was_exceeded); 426 427 // First-level mutator allocation attempt: try to allocate out of 428 // the mutator alloc region without taking the Heap_lock. This 429 // should only be used for non-humongous allocations. 430 inline HeapWord* attempt_allocation(size_t min_word_size, 431 size_t desired_word_size, 432 size_t* actual_word_size); 433 434 // Second-level mutator allocation attempt: take the Heap_lock and 435 // retry the allocation attempt, potentially scheduling a GC 436 // pause. This should only be used for non-humongous allocations. 437 HeapWord* attempt_allocation_slow(size_t word_size); 438 439 // Takes the Heap_lock and attempts a humongous allocation. It can 440 // potentially schedule a GC pause. 441 HeapWord* attempt_allocation_humongous(size_t word_size); 442 443 // Allocation attempt that should be called during safepoints (e.g., 444 // at the end of a successful GC). expect_null_mutator_alloc_region 445 // specifies whether the mutator alloc region is expected to be NULL 446 // or not. 447 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 448 bool expect_null_mutator_alloc_region); 449 450 // These methods are the "callbacks" from the G1AllocRegion class. 451 452 // For mutator alloc regions. 453 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 454 void retire_mutator_alloc_region(HeapRegion* alloc_region, 455 size_t allocated_bytes); 456 457 // For GC alloc regions. 458 bool has_more_regions(InCSetState dest); 459 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest); 460 void retire_gc_alloc_region(HeapRegion* alloc_region, 461 size_t allocated_bytes, InCSetState dest); 462 463 // - if explicit_gc is true, the GC is for a System.gc() etc, 464 // otherwise it's for a failed allocation. 465 // - if clear_all_soft_refs is true, all soft references should be 466 // cleared during the GC. 467 // - it returns false if it is unable to do the collection due to the 468 // GC locker being active, true otherwise. 469 bool do_full_collection(bool explicit_gc, 470 bool clear_all_soft_refs); 471 472 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 473 virtual void do_full_collection(bool clear_all_soft_refs); 474 475 // Resize the heap if necessary after a full collection. 476 void resize_if_necessary_after_full_collection(); 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 // 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 clear_in_cset(const HeapRegion* hr) { 577 _in_cset_fast_test.clear(hr); 578 } 579 580 void clear_cset_fast_test() { 581 _in_cset_fast_test.clear(); 582 } 583 584 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 585 586 // This is called at the start of either a concurrent cycle or a Full 587 // GC to update the number of old marking cycles started. 588 void increment_old_marking_cycles_started(); 589 590 // This is called at the end of either a concurrent cycle or a Full 591 // GC to update the number of old marking cycles completed. Those two 592 // can happen in a nested fashion, i.e., we start a concurrent 593 // cycle, a Full GC happens half-way through it which ends first, 594 // and then the cycle notices that a Full GC happened and ends 595 // too. The concurrent parameter is a boolean to help us do a bit 596 // tighter consistency checking in the method. If concurrent is 597 // false, the caller is the inner caller in the nesting (i.e., the 598 // Full GC). If concurrent is true, the caller is the outer caller 599 // in this nesting (i.e., the concurrent cycle). Further nesting is 600 // not currently supported. The end of this call also notifies 601 // the FullGCCount_lock in case a Java thread is waiting for a full 602 // GC to happen (e.g., it called System.gc() with 603 // +ExplicitGCInvokesConcurrent). 604 void increment_old_marking_cycles_completed(bool concurrent); 605 606 uint old_marking_cycles_completed() { 607 return _old_marking_cycles_completed; 608 } 609 610 G1HRPrinter* hr_printer() { return &_hr_printer; } 611 612 // Allocates a new heap region instance. 613 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 614 615 // Allocate the highest free region in the reserved heap. This will commit 616 // regions as necessary. 617 HeapRegion* alloc_highest_free_region(); 618 619 // Frees a non-humongous region by initializing its contents and 620 // adding it to the free list that's passed as a parameter (this is 621 // usually a local list which will be appended to the master free 622 // list later). The used bytes of freed regions are accumulated in 623 // pre_used. If skip_remset is true, the region's RSet will not be freed 624 // up. If skip_hot_card_cache is true, the region's hot card cache will not 625 // be freed up. The assumption is that this will be done later. 626 // The locked parameter indicates if the caller has already taken 627 // care of proper synchronization. This may allow some optimizations. 628 void free_region(HeapRegion* hr, 629 FreeRegionList* free_list, 630 bool skip_remset, 631 bool skip_hot_card_cache = false, 632 bool locked = false); 633 634 // It dirties the cards that cover the block so that the post 635 // write barrier never queues anything when updating objects on this 636 // block. It is assumed (and in fact we assert) that the block 637 // belongs to a young region. 638 inline void dirty_young_block(HeapWord* start, size_t word_size); 639 640 // Frees a humongous region by collapsing it into individual regions 641 // and calling free_region() for each of them. The freed regions 642 // will be added to the free list that's passed as a parameter (this 643 // is usually a local list which will be appended to the master free 644 // list later). 645 // The method assumes that only a single thread is ever calling 646 // this for a particular region at once. 647 void free_humongous_region(HeapRegion* hr, 648 FreeRegionList* free_list); 649 650 // Facility for allocating in 'archive' regions in high heap memory and 651 // recording the allocated ranges. These should all be called from the 652 // VM thread at safepoints, without the heap lock held. They can be used 653 // to create and archive a set of heap regions which can be mapped at the 654 // same fixed addresses in a subsequent JVM invocation. 655 void begin_archive_alloc_range(bool open = false); 656 657 // Check if the requested size would be too large for an archive allocation. 658 bool is_archive_alloc_too_large(size_t word_size); 659 660 // Allocate memory of the requested size from the archive region. This will 661 // return NULL if the size is too large or if no memory is available. It 662 // does not trigger a garbage collection. 663 HeapWord* archive_mem_allocate(size_t word_size); 664 665 // Optionally aligns the end address and returns the allocated ranges in 666 // an array of MemRegions in order of ascending addresses. 667 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 668 size_t end_alignment_in_bytes = 0); 669 670 // Facility for allocating a fixed range within the heap and marking 671 // the containing regions as 'archive'. For use at JVM init time, when the 672 // caller may mmap archived heap data at the specified range(s). 673 // Verify that the MemRegions specified in the argument array are within the 674 // reserved heap. 675 bool check_archive_addresses(MemRegion* range, size_t count); 676 677 // Commit the appropriate G1 regions containing the specified MemRegions 678 // and mark them as 'archive' regions. The regions in the array must be 679 // non-overlapping and in order of ascending address. 680 bool alloc_archive_regions(MemRegion* range, size_t count, bool open); 681 682 // Insert any required filler objects in the G1 regions around the specified 683 // ranges to make the regions parseable. This must be called after 684 // alloc_archive_regions, and after class loading has occurred. 685 void fill_archive_regions(MemRegion* range, size_t count); 686 687 // For each of the specified MemRegions, uncommit the containing G1 regions 688 // which had been allocated by alloc_archive_regions. This should be called 689 // rather than fill_archive_regions at JVM init time if the archive file 690 // mapping failed, with the same non-overlapping and sorted MemRegion array. 691 void dealloc_archive_regions(MemRegion* range, size_t count); 692 693 oop materialize_archived_object(oop obj); 694 695 private: 696 697 // Shrink the garbage-first heap by at most the given size (in bytes!). 698 // (Rounds down to a HeapRegion boundary.) 699 void shrink(size_t expand_bytes); 700 void shrink_helper(size_t expand_bytes); 701 702 #if TASKQUEUE_STATS 703 static void print_taskqueue_stats_hdr(outputStream* const st); 704 void print_taskqueue_stats() const; 705 void reset_taskqueue_stats(); 706 #endif // TASKQUEUE_STATS 707 708 // Schedule the VM operation that will do an evacuation pause to 709 // satisfy an allocation request of word_size. *succeeded will 710 // return whether the VM operation was successful (it did do an 711 // evacuation pause) or not (another thread beat us to it or the GC 712 // locker was active). Given that we should not be holding the 713 // Heap_lock when we enter this method, we will pass the 714 // gc_count_before (i.e., total_collections()) as a parameter since 715 // it has to be read while holding the Heap_lock. Currently, both 716 // methods that call do_collection_pause() release the Heap_lock 717 // before the call, so it's easy to read gc_count_before just before. 718 HeapWord* do_collection_pause(size_t word_size, 719 uint gc_count_before, 720 bool* succeeded, 721 GCCause::Cause gc_cause); 722 723 void wait_for_root_region_scanning(); 724 725 // The guts of the incremental collection pause, executed by the vm 726 // thread. It returns false if it is unable to do the collection due 727 // to the GC locker being active, true otherwise 728 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 729 730 // Actually do the work of evacuating the collection set. 731 void evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states); 732 733 void pre_evacuate_collection_set(); 734 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 735 736 // Print the header for the per-thread termination statistics. 737 static void print_termination_stats_hdr(); 738 // Print actual per-thread termination statistics. 739 void print_termination_stats(uint worker_id, 740 double elapsed_ms, 741 double strong_roots_ms, 742 double term_ms, 743 size_t term_attempts, 744 size_t alloc_buffer_waste, 745 size_t undo_waste) const; 746 // Update object copying statistics. 747 void record_obj_copy_mem_stats(); 748 749 // The hot card cache for remembered set insertion optimization. 750 G1HotCardCache* _hot_card_cache; 751 752 // The g1 remembered set of the heap. 753 G1RemSet* _g1_rem_set; 754 755 // A set of cards that cover the objects for which the Rsets should be updated 756 // concurrently after the collection. 757 DirtyCardQueueSet _dirty_card_queue_set; 758 759 // After a collection pause, convert the regions in the collection set into free 760 // regions. 761 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 762 763 // Abandon the current collection set without recording policy 764 // statistics or updating free lists. 765 void abandon_collection_set(G1CollectionSet* collection_set); 766 767 // The concurrent marker (and the thread it runs in.) 768 G1ConcurrentMark* _cm; 769 G1ConcurrentMarkThread* _cm_thread; 770 771 // The concurrent refiner. 772 G1ConcurrentRefine* _cr; 773 774 // The parallel task queues 775 RefToScanQueueSet *_task_queues; 776 777 // True iff a evacuation has failed in the current collection. 778 bool _evacuation_failed; 779 780 EvacuationFailedInfo* _evacuation_failed_info_array; 781 782 // Failed evacuations cause some logical from-space objects to have 783 // forwarding pointers to themselves. Reset them. 784 void remove_self_forwarding_pointers(); 785 786 // Restore the objects in the regions in the collection set after an 787 // evacuation failure. 788 void restore_after_evac_failure(); 789 790 PreservedMarksSet _preserved_marks_set; 791 792 // Preserve the mark of "obj", if necessary, in preparation for its mark 793 // word being overwritten with a self-forwarding-pointer. 794 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 795 796 #ifndef PRODUCT 797 // Support for forcing evacuation failures. Analogous to 798 // PromotionFailureALot for the other collectors. 799 800 // Records whether G1EvacuationFailureALot should be in effect 801 // for the current GC 802 bool _evacuation_failure_alot_for_current_gc; 803 804 // Used to record the GC number for interval checking when 805 // determining whether G1EvaucationFailureALot is in effect 806 // for the current GC. 807 size_t _evacuation_failure_alot_gc_number; 808 809 // Count of the number of evacuations between failures. 810 volatile size_t _evacuation_failure_alot_count; 811 812 // Set whether G1EvacuationFailureALot should be in effect 813 // for the current GC (based upon the type of GC and which 814 // command line flags are set); 815 inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc, 816 bool during_initial_mark, 817 bool mark_or_rebuild_in_progress); 818 819 inline void set_evacuation_failure_alot_for_current_gc(); 820 821 // Return true if it's time to cause an evacuation failure. 822 inline bool evacuation_should_fail(); 823 824 // Reset the G1EvacuationFailureALot counters. Should be called at 825 // the end of an evacuation pause in which an evacuation failure occurred. 826 inline void reset_evacuation_should_fail(); 827 #endif // !PRODUCT 828 829 // ("Weak") Reference processing support. 830 // 831 // G1 has 2 instances of the reference processor class. One 832 // (_ref_processor_cm) handles reference object discovery 833 // and subsequent processing during concurrent marking cycles. 834 // 835 // The other (_ref_processor_stw) handles reference object 836 // discovery and processing during full GCs and incremental 837 // evacuation pauses. 838 // 839 // During an incremental pause, reference discovery will be 840 // temporarily disabled for _ref_processor_cm and will be 841 // enabled for _ref_processor_stw. At the end of the evacuation 842 // pause references discovered by _ref_processor_stw will be 843 // processed and discovery will be disabled. The previous 844 // setting for reference object discovery for _ref_processor_cm 845 // will be re-instated. 846 // 847 // At the start of marking: 848 // * Discovery by the CM ref processor is verified to be inactive 849 // and it's discovered lists are empty. 850 // * Discovery by the CM ref processor is then enabled. 851 // 852 // At the end of marking: 853 // * Any references on the CM ref processor's discovered 854 // lists are processed (possibly MT). 855 // 856 // At the start of full GC we: 857 // * Disable discovery by the CM ref processor and 858 // empty CM ref processor's discovered lists 859 // (without processing any entries). 860 // * Verify that the STW ref processor is inactive and it's 861 // discovered lists are empty. 862 // * Temporarily set STW ref processor discovery as single threaded. 863 // * Temporarily clear the STW ref processor's _is_alive_non_header 864 // field. 865 // * Finally enable discovery by the STW ref processor. 866 // 867 // The STW ref processor is used to record any discovered 868 // references during the full GC. 869 // 870 // At the end of a full GC we: 871 // * Enqueue any reference objects discovered by the STW ref processor 872 // that have non-live referents. This has the side-effect of 873 // making the STW ref processor inactive by disabling discovery. 874 // * Verify that the CM ref processor is still inactive 875 // and no references have been placed on it's discovered 876 // lists (also checked as a precondition during initial marking). 877 878 // The (stw) reference processor... 879 ReferenceProcessor* _ref_processor_stw; 880 881 // During reference object discovery, the _is_alive_non_header 882 // closure (if non-null) is applied to the referent object to 883 // determine whether the referent is live. If so then the 884 // reference object does not need to be 'discovered' and can 885 // be treated as a regular oop. This has the benefit of reducing 886 // the number of 'discovered' reference objects that need to 887 // be processed. 888 // 889 // Instance of the is_alive closure for embedding into the 890 // STW reference processor as the _is_alive_non_header field. 891 // Supplying a value for the _is_alive_non_header field is 892 // optional but doing so prevents unnecessary additions to 893 // the discovered lists during reference discovery. 894 G1STWIsAliveClosure _is_alive_closure_stw; 895 896 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw; 897 898 // The (concurrent marking) reference processor... 899 ReferenceProcessor* _ref_processor_cm; 900 901 // Instance of the concurrent mark is_alive closure for embedding 902 // into the Concurrent Marking reference processor as the 903 // _is_alive_non_header field. Supplying a value for the 904 // _is_alive_non_header field is optional but doing so prevents 905 // unnecessary additions to the discovered lists during reference 906 // discovery. 907 G1CMIsAliveClosure _is_alive_closure_cm; 908 909 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm; 910 public: 911 912 RefToScanQueue *task_queue(uint i) const; 913 914 uint num_task_queues() const; 915 916 // A set of cards where updates happened during the GC 917 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 918 919 // Create a G1CollectedHeap with the specified policy. 920 // Must call the initialize method afterwards. 921 // May not return if something goes wrong. 922 G1CollectedHeap(G1CollectorPolicy* policy); 923 924 private: 925 jint initialize_concurrent_refinement(); 926 jint initialize_young_gen_sampling_thread(); 927 public: 928 // Initialize the G1CollectedHeap to have the initial and 929 // maximum sizes and remembered and barrier sets 930 // specified by the policy object. 931 jint initialize(); 932 933 virtual void stop(); 934 virtual void safepoint_synchronize_begin(); 935 virtual void safepoint_synchronize_end(); 936 937 // Return the (conservative) maximum heap alignment for any G1 heap 938 static size_t conservative_max_heap_alignment(); 939 940 // Does operations required after initialization has been done. 941 void post_initialize(); 942 943 // Initialize weak reference processing. 944 void ref_processing_init(); 945 946 virtual Name kind() const { 947 return CollectedHeap::G1; 948 } 949 950 virtual const char* name() const { 951 return "G1"; 952 } 953 954 const G1CollectorState* collector_state() const { return &_collector_state; } 955 G1CollectorState* collector_state() { return &_collector_state; } 956 957 // The current policy object for the collector. 958 G1Policy* g1_policy() const { return _g1_policy; } 959 960 HeapRegionManager* hrm() const { return _hrm; } 961 962 bool is_hetero_heap() const { return _is_hetero_heap; } 963 964 const G1CollectionSet* collection_set() const { return &_collection_set; } 965 G1CollectionSet* collection_set() { return &_collection_set; } 966 967 virtual CollectorPolicy* collector_policy() const; 968 969 virtual SoftRefPolicy* soft_ref_policy(); 970 971 virtual void initialize_serviceability(); 972 virtual MemoryUsage memory_usage(); 973 virtual GrowableArray<GCMemoryManager*> memory_managers(); 974 virtual GrowableArray<MemoryPool*> memory_pools(); 975 976 // The rem set and barrier set. 977 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 978 979 // Try to minimize the remembered set. 980 void scrub_rem_set(); 981 982 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 983 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i); 984 985 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. 986 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i); 987 988 // The shared block offset table array. 989 G1BlockOffsetTable* bot() const { return _bot; } 990 991 // Reference Processing accessors 992 993 // The STW reference processor.... 994 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 995 996 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 997 998 // The Concurrent Marking reference processor... 999 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1000 1001 size_t unused_committed_regions_in_bytes() const; 1002 virtual size_t capacity() const; 1003 virtual size_t used() const; 1004 // This should be called when we're not holding the heap lock. The 1005 // result might be a bit inaccurate. 1006 size_t used_unlocked() const; 1007 size_t recalculate_used() const; 1008 1009 // These virtual functions do the actual allocation. 1010 // Some heaps may offer a contiguous region for shared non-blocking 1011 // allocation, via inlined code (by exporting the address of the top and 1012 // end fields defining the extent of the contiguous allocation region.) 1013 // But G1CollectedHeap doesn't yet support this. 1014 1015 virtual bool is_maximal_no_gc() const { 1016 return _hrm->available() == 0; 1017 } 1018 1019 // Returns whether there are any regions left in the heap for allocation. 1020 bool has_regions_left_for_allocation() const { 1021 return !is_maximal_no_gc() || num_free_regions() != 0; 1022 } 1023 1024 // The current number of regions in the heap. 1025 uint num_regions() const { return _hrm->length(); } 1026 1027 // The max number of regions in the heap. 1028 uint max_regions() const { return _hrm->max_length(); } 1029 1030 // Max number of regions that can be comitted. 1031 uint max_expandable_regions() const { return _hrm->max_expandable_length(); } 1032 1033 // The number of regions that are completely free. 1034 uint num_free_regions() const { return _hrm->num_free_regions(); } 1035 1036 MemoryUsage get_auxiliary_data_memory_usage() const { 1037 return _hrm->get_auxiliary_data_memory_usage(); 1038 } 1039 1040 // The number of regions that are not completely free. 1041 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1042 1043 #ifdef ASSERT 1044 bool is_on_master_free_list(HeapRegion* hr) { 1045 return _hrm->is_free(hr); 1046 } 1047 #endif // ASSERT 1048 1049 inline void old_set_add(HeapRegion* hr); 1050 inline void old_set_remove(HeapRegion* hr); 1051 1052 inline void archive_set_add(HeapRegion* hr); 1053 1054 size_t non_young_capacity_bytes() { 1055 return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes; 1056 } 1057 1058 // Determine whether the given region is one that we are using as an 1059 // old GC alloc region. 1060 bool is_old_gc_alloc_region(HeapRegion* hr); 1061 1062 // Perform a collection of the heap; intended for use in implementing 1063 // "System.gc". This probably implies as full a collection as the 1064 // "CollectedHeap" supports. 1065 virtual void collect(GCCause::Cause cause); 1066 1067 // True iff an evacuation has failed in the most-recent collection. 1068 bool evacuation_failed() { return _evacuation_failed; } 1069 1070 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed); 1071 void prepend_to_freelist(FreeRegionList* list); 1072 void decrement_summary_bytes(size_t bytes); 1073 1074 virtual bool is_in(const void* p) const; 1075 #ifdef ASSERT 1076 // Returns whether p is in one of the available areas of the heap. Slow but 1077 // extensive version. 1078 bool is_in_exact(const void* p) const; 1079 #endif 1080 1081 // Return "TRUE" iff the given object address is within the collection 1082 // set. Assumes that the reference points into the heap. 1083 inline bool is_in_cset(const HeapRegion *hr); 1084 inline bool is_in_cset(oop obj); 1085 inline bool is_in_cset(HeapWord* addr); 1086 1087 inline bool is_in_cset_or_humongous(const oop obj); 1088 1089 private: 1090 // This array is used for a quick test on whether a reference points into 1091 // the collection set or not. Each of the array's elements denotes whether the 1092 // corresponding region is in the collection set or not. 1093 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1094 1095 public: 1096 1097 inline InCSetState in_cset_state(const oop obj); 1098 1099 // Return "TRUE" iff the given object address is in the reserved 1100 // region of g1. 1101 bool is_in_g1_reserved(const void* p) const { 1102 return _hrm->reserved().contains(p); 1103 } 1104 1105 // Returns a MemRegion that corresponds to the space that has been 1106 // reserved for the heap 1107 MemRegion g1_reserved() const { 1108 return _hrm->reserved(); 1109 } 1110 1111 virtual bool is_in_closed_subset(const void* p) const; 1112 1113 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; } 1114 1115 G1CardTable* card_table() const { 1116 return _card_table; 1117 } 1118 1119 // Iteration functions. 1120 1121 // Iterate over all objects, calling "cl.do_object" on each. 1122 virtual void object_iterate(ObjectClosure* cl); 1123 1124 virtual void safe_object_iterate(ObjectClosure* cl) { 1125 object_iterate(cl); 1126 } 1127 1128 // Iterate over heap regions, in address order, terminating the 1129 // iteration early if the "do_heap_region" method returns "true". 1130 void heap_region_iterate(HeapRegionClosure* blk) const; 1131 1132 // Return the region with the given index. It assumes the index is valid. 1133 inline HeapRegion* region_at(uint index) const; 1134 1135 // Return the next region (by index) that is part of the same 1136 // humongous object that hr is part of. 1137 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1138 1139 // Calculate the region index of the given address. Given address must be 1140 // within the heap. 1141 inline uint addr_to_region(HeapWord* addr) const; 1142 1143 inline HeapWord* bottom_addr_for_region(uint index) const; 1144 1145 // Two functions to iterate over the heap regions in parallel. Threads 1146 // compete using the HeapRegionClaimer to claim the regions before 1147 // applying the closure on them. 1148 // The _from_worker_offset version uses the HeapRegionClaimer and 1149 // the worker id to calculate a start offset to prevent all workers to 1150 // start from the point. 1151 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 1152 HeapRegionClaimer* hrclaimer, 1153 uint worker_id) const; 1154 1155 void heap_region_par_iterate_from_start(HeapRegionClosure* cl, 1156 HeapRegionClaimer* hrclaimer) const; 1157 1158 // Iterate over the regions (if any) in the current collection set. 1159 void collection_set_iterate(HeapRegionClosure* blk); 1160 1161 // Iterate over the regions (if any) in the current collection set. Starts the 1162 // iteration over the entire collection set so that the start regions of a given 1163 // worker id over the set active_workers are evenly spread across the set of 1164 // collection set regions. 1165 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id); 1166 1167 // Returns the HeapRegion that contains addr. addr must not be NULL. 1168 template <class T> 1169 inline HeapRegion* heap_region_containing(const T addr) const; 1170 1171 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1172 // each address in the (reserved) heap is a member of exactly 1173 // one block. The defining characteristic of a block is that it is 1174 // possible to find its size, and thus to progress forward to the next 1175 // block. (Blocks may be of different sizes.) Thus, blocks may 1176 // represent Java objects, or they might be free blocks in a 1177 // free-list-based heap (or subheap), as long as the two kinds are 1178 // distinguishable and the size of each is determinable. 1179 1180 // Returns the address of the start of the "block" that contains the 1181 // address "addr". We say "blocks" instead of "object" since some heaps 1182 // may not pack objects densely; a chunk may either be an object or a 1183 // non-object. 1184 virtual HeapWord* block_start(const void* addr) const; 1185 1186 // Requires "addr" to be the start of a chunk, and returns its size. 1187 // "addr + size" is required to be the start of a new chunk, or the end 1188 // of the active area of the heap. 1189 virtual size_t block_size(const HeapWord* addr) const; 1190 1191 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1192 // the block is an object. 1193 virtual bool block_is_obj(const HeapWord* addr) const; 1194 1195 // Section on thread-local allocation buffers (TLABs) 1196 // See CollectedHeap for semantics. 1197 1198 bool supports_tlab_allocation() const; 1199 size_t tlab_capacity(Thread* ignored) const; 1200 size_t tlab_used(Thread* ignored) const; 1201 size_t max_tlab_size() const; 1202 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1203 1204 inline bool is_in_young(const oop obj); 1205 1206 // Returns "true" iff the given word_size is "very large". 1207 static bool is_humongous(size_t word_size) { 1208 // Note this has to be strictly greater-than as the TLABs 1209 // are capped at the humongous threshold and we want to 1210 // ensure that we don't try to allocate a TLAB as 1211 // humongous and that we don't allocate a humongous 1212 // object in a TLAB. 1213 return word_size > _humongous_object_threshold_in_words; 1214 } 1215 1216 // Returns the humongous threshold for a specific region size 1217 static size_t humongous_threshold_for(size_t region_size) { 1218 return (region_size / 2); 1219 } 1220 1221 // Returns the number of regions the humongous object of the given word size 1222 // requires. 1223 static size_t humongous_obj_size_in_regions(size_t word_size); 1224 1225 // Print the maximum heap capacity. 1226 virtual size_t max_capacity() const; 1227 1228 // Return the size of reserved memory. Returns different value than max_capacity() when AllocateOldGenAt is used. 1229 virtual size_t max_reserved_capacity() const; 1230 1231 virtual jlong millis_since_last_gc(); 1232 1233 1234 // Convenience function to be used in situations where the heap type can be 1235 // asserted to be this type. 1236 static G1CollectedHeap* heap(); 1237 1238 void set_region_short_lived_locked(HeapRegion* hr); 1239 // add appropriate methods for any other surv rate groups 1240 1241 const G1SurvivorRegions* survivor() const { return &_survivor; } 1242 1243 uint eden_regions_count() const { return _eden.length(); } 1244 uint survivor_regions_count() const { return _survivor.length(); } 1245 uint young_regions_count() const { return _eden.length() + _survivor.length(); } 1246 uint old_regions_count() const { return _old_set.length(); } 1247 uint archive_regions_count() const { return _archive_set.length(); } 1248 uint humongous_regions_count() const { return _humongous_set.length(); } 1249 1250 #ifdef ASSERT 1251 bool check_young_list_empty(); 1252 #endif 1253 1254 // *** Stuff related to concurrent marking. It's not clear to me that so 1255 // many of these need to be public. 1256 1257 // The functions below are helper functions that a subclass of 1258 // "CollectedHeap" can use in the implementation of its virtual 1259 // functions. 1260 // This performs a concurrent marking of the live objects in a 1261 // bitmap off to the side. 1262 void do_concurrent_mark(); 1263 1264 bool is_marked_next(oop obj) const; 1265 1266 // Determine if an object is dead, given the object and also 1267 // the region to which the object belongs. An object is dead 1268 // iff a) it was not allocated since the last mark, b) it 1269 // is not marked, and c) it is not in an archive region. 1270 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1271 return 1272 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) && 1273 !hr->is_archive(); 1274 } 1275 1276 // This function returns true when an object has been 1277 // around since the previous marking and hasn't yet 1278 // been marked during this marking, and is not in an archive region. 1279 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1280 return 1281 !hr->obj_allocated_since_next_marking(obj) && 1282 !is_marked_next(obj) && 1283 !hr->is_archive(); 1284 } 1285 1286 // Determine if an object is dead, given only the object itself. 1287 // This will find the region to which the object belongs and 1288 // then call the region version of the same function. 1289 1290 // Added if it is NULL it isn't dead. 1291 1292 inline bool is_obj_dead(const oop obj) const; 1293 1294 inline bool is_obj_ill(const oop obj) const; 1295 1296 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const; 1297 inline bool is_obj_dead_full(const oop obj) const; 1298 1299 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1300 1301 // Refinement 1302 1303 G1ConcurrentRefine* concurrent_refine() const { return _cr; } 1304 1305 // Optimized nmethod scanning support routines 1306 1307 // Is an oop scavengeable 1308 virtual bool is_scavengable(oop obj); 1309 1310 // Register the given nmethod with the G1 heap. 1311 virtual void register_nmethod(nmethod* nm); 1312 1313 // Unregister the given nmethod from the G1 heap. 1314 virtual void unregister_nmethod(nmethod* nm); 1315 1316 // Free up superfluous code root memory. 1317 void purge_code_root_memory(); 1318 1319 // Rebuild the strong code root lists for each region 1320 // after a full GC. 1321 void rebuild_strong_code_roots(); 1322 1323 // Partial cleaning used when class unloading is disabled. 1324 // Let the caller choose what structures to clean out: 1325 // - StringTable 1326 // - StringDeduplication structures 1327 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_string_dedup); 1328 1329 // Complete cleaning used when class unloading is enabled. 1330 // Cleans out all structures handled by partial_cleaning and also the CodeCache. 1331 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); 1332 1333 // Redirty logged cards in the refinement queue. 1334 void redirty_logged_cards(); 1335 // Verification 1336 1337 // Deduplicate the string 1338 virtual void deduplicate_string(oop str); 1339 1340 // Perform any cleanup actions necessary before allowing a verification. 1341 virtual void prepare_for_verify(); 1342 1343 // Perform verification. 1344 1345 // vo == UsePrevMarking -> use "prev" marking information, 1346 // vo == UseNextMarking -> use "next" marking information 1347 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS 1348 // 1349 // NOTE: Only the "prev" marking information is guaranteed to be 1350 // consistent most of the time, so most calls to this should use 1351 // vo == UsePrevMarking. 1352 // Currently, there is only one case where this is called with 1353 // vo == UseNextMarking, which is to verify the "next" marking 1354 // information at the end of remark. 1355 // Currently there is only one place where this is called with 1356 // vo == UseFullMarking, which is to verify the marking during a 1357 // full GC. 1358 void verify(VerifyOption vo); 1359 1360 // WhiteBox testing support. 1361 virtual bool supports_concurrent_phase_control() const; 1362 virtual const char* const* concurrent_phases() const; 1363 virtual bool request_concurrent_phase(const char* phase); 1364 1365 virtual WorkGang* get_safepoint_workers() { return _workers; } 1366 1367 // The methods below are here for convenience and dispatch the 1368 // appropriate method depending on value of the given VerifyOption 1369 // parameter. The values for that parameter, and their meanings, 1370 // are the same as those above. 1371 1372 bool is_obj_dead_cond(const oop obj, 1373 const HeapRegion* hr, 1374 const VerifyOption vo) const; 1375 1376 bool is_obj_dead_cond(const oop obj, 1377 const VerifyOption vo) const; 1378 1379 G1HeapSummary create_g1_heap_summary(); 1380 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1381 1382 // Printing 1383 private: 1384 void print_heap_regions() const; 1385 void print_regions_on(outputStream* st) const; 1386 1387 public: 1388 virtual void print_on(outputStream* st) const; 1389 virtual void print_extended_on(outputStream* st) const; 1390 virtual void print_on_error(outputStream* st) const; 1391 1392 virtual void print_gc_threads_on(outputStream* st) const; 1393 virtual void gc_threads_do(ThreadClosure* tc) const; 1394 1395 // Override 1396 void print_tracing_info() const; 1397 1398 // The following two methods are helpful for debugging RSet issues. 1399 void print_cset_rsets() PRODUCT_RETURN; 1400 void print_all_rsets() PRODUCT_RETURN; 1401 1402 size_t pending_card_num(); 1403 }; 1404 1405 class G1ParEvacuateFollowersClosure : public VoidClosure { 1406 private: 1407 double _start_term; 1408 double _term_time; 1409 size_t _term_attempts; 1410 1411 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 1412 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 1413 protected: 1414 G1CollectedHeap* _g1h; 1415 G1ParScanThreadState* _par_scan_state; 1416 RefToScanQueueSet* _queues; 1417 ParallelTaskTerminator* _terminator; 1418 1419 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 1420 RefToScanQueueSet* queues() { return _queues; } 1421 ParallelTaskTerminator* terminator() { return _terminator; } 1422 1423 public: 1424 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 1425 G1ParScanThreadState* par_scan_state, 1426 RefToScanQueueSet* queues, 1427 ParallelTaskTerminator* terminator) 1428 : _start_term(0.0), _term_time(0.0), _term_attempts(0), 1429 _g1h(g1h), _par_scan_state(par_scan_state), 1430 _queues(queues), _terminator(terminator) {} 1431 1432 void do_void(); 1433 1434 double term_time() const { return _term_time; } 1435 size_t term_attempts() const { return _term_attempts; } 1436 1437 private: 1438 inline bool offer_termination(); 1439 }; 1440 1441 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP