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/heapRegionSet.hpp" 47 #include "gc/shared/barrierSet.hpp" 48 #include "gc/shared/collectedHeap.hpp" 49 #include "gc/shared/gcHeapSummary.hpp" 50 #include "gc/shared/plab.hpp" 51 #include "gc/shared/preservedMarks.hpp" 52 #include "gc/shared/softRefPolicy.hpp" 53 #include "memory/memRegion.hpp" 54 #include "utilities/stack.hpp" 55 56 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 57 // It uses the "Garbage First" heap organization and algorithm, which 58 // may combine concurrent marking with parallel, incremental compaction of 59 // heap subsets that will yield large amounts of garbage. 60 61 // Forward declarations 62 class HeapRegion; 63 class HRRSCleanupTask; 64 class GenerationSpec; 65 class G1ParScanThreadState; 66 class G1ParScanThreadStateSet; 67 class G1ParScanThreadState; 68 class MemoryPool; 69 class MemoryManager; 70 class ObjectClosure; 71 class SpaceClosure; 72 class CompactibleSpaceClosure; 73 class Space; 74 class G1CollectionSet; 75 class G1CollectorPolicy; 76 class G1Policy; 77 class G1HotCardCache; 78 class G1RemSet; 79 class G1YoungRemSetSamplingThread; 80 class HeapRegionRemSetIterator; 81 class G1ConcurrentMark; 82 class G1ConcurrentMarkThread; 83 class G1ConcurrentRefine; 84 class GenerationCounters; 85 class STWGCTimer; 86 class G1NewTracer; 87 class EvacuationFailedInfo; 88 class nmethod; 89 class WorkGang; 90 class G1Allocator; 91 class G1ArchiveAllocator; 92 class G1FullGCScope; 93 class G1HeapVerifier; 94 class G1HeapSizingPolicy; 95 class G1HeapSummary; 96 class G1EvacSummary; 97 98 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 99 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 100 101 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 102 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 103 104 // The G1 STW is alive closure. 105 // An instance is embedded into the G1CH and used as the 106 // (optional) _is_alive_non_header closure in the STW 107 // reference processor. It is also extensively used during 108 // reference processing during STW evacuation pauses. 109 class G1STWIsAliveClosure : public BoolObjectClosure { 110 G1CollectedHeap* _g1h; 111 public: 112 G1STWIsAliveClosure(G1CollectedHeap* g1h) : _g1h(g1h) {} 113 bool do_object_b(oop p); 114 }; 115 116 class G1STWSubjectToDiscoveryClosure : public BoolObjectClosure { 117 G1CollectedHeap* _g1h; 118 public: 119 G1STWSubjectToDiscoveryClosure(G1CollectedHeap* g1h) : _g1h(g1h) {} 120 bool do_object_b(oop p); 121 }; 122 123 class G1RegionMappingChangedListener : public G1MappingChangedListener { 124 private: 125 void reset_from_card_cache(uint start_idx, size_t num_regions); 126 public: 127 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 128 }; 129 130 class G1CollectedHeap : public CollectedHeap { 131 friend class G1FreeCollectionSetTask; 132 friend class VM_CollectForMetadataAllocation; 133 friend class VM_G1CollectForAllocation; 134 friend class VM_G1CollectFull; 135 friend class VMStructs; 136 friend class MutatorAllocRegion; 137 friend class G1FullCollector; 138 friend class G1GCAllocRegion; 139 friend class G1HeapVerifier; 140 141 // Closures used in implementation. 142 friend class G1ParScanThreadState; 143 friend class G1ParScanThreadStateSet; 144 friend class G1ParTask; 145 friend class G1PLABAllocator; 146 friend class G1PrepareCompactClosure; 147 148 // Other related classes. 149 friend class HeapRegionClaimer; 150 151 // Testing classes. 152 friend class G1CheckCSetFastTableClosure; 153 154 private: 155 G1YoungRemSetSamplingThread* _young_gen_sampling_thread; 156 157 WorkGang* _workers; 158 G1CollectorPolicy* _collector_policy; 159 G1CardTable* _card_table; 160 161 SoftRefPolicy _soft_ref_policy; 162 163 static size_t _humongous_object_threshold_in_words; 164 165 // These sets keep track of old, archive and humongous regions respectively. 166 HeapRegionSet _old_set; 167 HeapRegionSet _archive_set; 168 HeapRegionSet _humongous_set; 169 170 void eagerly_reclaim_humongous_regions(); 171 // Start a new incremental collection set for the next pause. 172 void start_new_collection_set(); 173 174 // The block offset table for the G1 heap. 175 G1BlockOffsetTable* _bot; 176 177 // Tears down the region sets / lists so that they are empty and the 178 // regions on the heap do not belong to a region set / list. The 179 // only exception is the humongous set which we leave unaltered. If 180 // free_list_only is true, it will only tear down the master free 181 // list. It is called before a Full GC (free_list_only == false) or 182 // before heap shrinking (free_list_only == true). 183 void tear_down_region_sets(bool free_list_only); 184 185 // Rebuilds the region sets / lists so that they are repopulated to 186 // reflect the contents of the heap. The only exception is the 187 // humongous set which was not torn down in the first place. If 188 // free_list_only is true, it will only rebuild the master free 189 // list. It is called after a Full GC (free_list_only == false) or 190 // after heap shrinking (free_list_only == true). 191 void rebuild_region_sets(bool free_list_only); 192 193 // Callback for region mapping changed events. 194 G1RegionMappingChangedListener _listener; 195 196 // The sequence of all heap regions in the heap. 197 HeapRegionManager _hrm; 198 199 // Manages all allocations with regions except humongous object allocations. 200 G1Allocator* _allocator; 201 202 // Manages all heap verification. 203 G1HeapVerifier* _verifier; 204 205 // Outside of GC pauses, the number of bytes used in all regions other 206 // than the current allocation region(s). 207 size_t _summary_bytes_used; 208 209 void increase_used(size_t bytes); 210 void decrease_used(size_t bytes); 211 212 void set_used(size_t bytes); 213 214 // Class that handles archive allocation ranges. 215 G1ArchiveAllocator* _archive_allocator; 216 217 // GC allocation statistics policy for survivors. 218 G1EvacStats _survivor_evac_stats; 219 220 // GC allocation statistics policy for tenured objects. 221 G1EvacStats _old_evac_stats; 222 223 // It specifies whether we should attempt to expand the heap after a 224 // region allocation failure. If heap expansion fails we set this to 225 // false so that we don't re-attempt the heap expansion (it's likely 226 // that subsequent expansion attempts will also fail if one fails). 227 // Currently, it is only consulted during GC and it's reset at the 228 // start of each GC. 229 bool _expand_heap_after_alloc_failure; 230 231 // Helper for monitoring and management support. 232 G1MonitoringSupport* _g1mm; 233 234 // Records whether the region at the given index is (still) a 235 // candidate for eager reclaim. Only valid for humongous start 236 // regions; other regions have unspecified values. Humongous start 237 // regions are initialized at start of collection pause, with 238 // candidates removed from the set as they are found reachable from 239 // roots or the young generation. 240 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 241 protected: 242 bool default_value() const { return false; } 243 public: 244 void clear() { G1BiasedMappedArray<bool>::clear(); } 245 void set_candidate(uint region, bool value) { 246 set_by_index(region, value); 247 } 248 bool is_candidate(uint region) { 249 return get_by_index(region); 250 } 251 }; 252 253 HumongousReclaimCandidates _humongous_reclaim_candidates; 254 // Stores whether during humongous object registration we found candidate regions. 255 // If not, we can skip a few steps. 256 bool _has_humongous_reclaim_candidates; 257 258 G1HRPrinter _hr_printer; 259 260 // It decides whether an explicit GC should start a concurrent cycle 261 // instead of doing a STW GC. Currently, a concurrent cycle is 262 // explicitly started if: 263 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 264 // (b) cause == _g1_humongous_allocation 265 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 266 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 267 // (e) cause == _wb_conc_mark 268 bool should_do_concurrent_full_gc(GCCause::Cause cause); 269 270 // indicates whether we are in young or mixed GC mode 271 G1CollectorState _collector_state; 272 273 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 274 // concurrent cycles) we have started. 275 volatile uint _old_marking_cycles_started; 276 277 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 278 // concurrent cycles) we have completed. 279 volatile uint _old_marking_cycles_completed; 280 281 // This is a non-product method that is helpful for testing. It is 282 // called at the end of a GC and artificially expands the heap by 283 // allocating a number of dead regions. This way we can induce very 284 // frequent marking cycles and stress the cleanup / concurrent 285 // cleanup code more (as all the regions that will be allocated by 286 // this method will be found dead by the marking cycle). 287 void allocate_dummy_regions() PRODUCT_RETURN; 288 289 // If the HR printer is active, dump the state of the regions in the 290 // heap after a compaction. 291 void print_hrm_post_compaction(); 292 293 // Create a memory mapper for auxiliary data structures of the given size and 294 // translation factor. 295 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 296 size_t size, 297 size_t translation_factor); 298 299 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 300 301 // These are macros so that, if the assert fires, we get the correct 302 // line number, file, etc. 303 304 #define heap_locking_asserts_params(_extra_message_) \ 305 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 306 (_extra_message_), \ 307 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 308 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 309 BOOL_TO_STR(Thread::current()->is_VM_thread()) 310 311 #define assert_heap_locked() \ 312 do { \ 313 assert(Heap_lock->owned_by_self(), \ 314 heap_locking_asserts_params("should be holding the Heap_lock")); \ 315 } while (0) 316 317 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 318 do { \ 319 assert(Heap_lock->owned_by_self() || \ 320 (SafepointSynchronize::is_at_safepoint() && \ 321 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 322 heap_locking_asserts_params("should be holding the Heap_lock or " \ 323 "should be at a safepoint")); \ 324 } while (0) 325 326 #define assert_heap_locked_and_not_at_safepoint() \ 327 do { \ 328 assert(Heap_lock->owned_by_self() && \ 329 !SafepointSynchronize::is_at_safepoint(), \ 330 heap_locking_asserts_params("should be holding the Heap_lock and " \ 331 "should not be at a safepoint")); \ 332 } while (0) 333 334 #define assert_heap_not_locked() \ 335 do { \ 336 assert(!Heap_lock->owned_by_self(), \ 337 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 338 } while (0) 339 340 #define assert_heap_not_locked_and_not_at_safepoint() \ 341 do { \ 342 assert(!Heap_lock->owned_by_self() && \ 343 !SafepointSynchronize::is_at_safepoint(), \ 344 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 345 "should not be at a safepoint")); \ 346 } while (0) 347 348 #define assert_at_safepoint_on_vm_thread() \ 349 do { \ 350 assert_at_safepoint(); \ 351 assert(Thread::current_or_null() != NULL, "no current thread"); \ 352 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \ 353 } while (0) 354 355 // The young region list. 356 G1EdenRegions _eden; 357 G1SurvivorRegions _survivor; 358 359 STWGCTimer* _gc_timer_stw; 360 361 G1NewTracer* _gc_tracer_stw; 362 363 // The current policy object for the collector. 364 G1Policy* _g1_policy; 365 G1HeapSizingPolicy* _heap_sizing_policy; 366 367 G1CollectionSet _collection_set; 368 369 // Try to allocate a single non-humongous HeapRegion sufficient for 370 // an allocation of the given word_size. If do_expand is true, 371 // attempt to expand the heap if necessary to satisfy the allocation 372 // request. If the region is to be used as an old region or for a 373 // humongous object, set is_old to true. If not, to false. 374 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 375 376 // Initialize a contiguous set of free regions of length num_regions 377 // and starting at index first so that they appear as a single 378 // humongous region. 379 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 380 uint num_regions, 381 size_t word_size); 382 383 // Attempt to allocate a humongous object of the given size. Return 384 // NULL if unsuccessful. 385 HeapWord* humongous_obj_allocate(size_t word_size); 386 387 // The following two methods, allocate_new_tlab() and 388 // mem_allocate(), are the two main entry points from the runtime 389 // into the G1's allocation routines. They have the following 390 // assumptions: 391 // 392 // * They should both be called outside safepoints. 393 // 394 // * They should both be called without holding the Heap_lock. 395 // 396 // * All allocation requests for new TLABs should go to 397 // allocate_new_tlab(). 398 // 399 // * All non-TLAB allocation requests should go to mem_allocate(). 400 // 401 // * If either call cannot satisfy the allocation request using the 402 // current allocating region, they will try to get a new one. If 403 // this fails, they will attempt to do an evacuation pause and 404 // retry the allocation. 405 // 406 // * If all allocation attempts fail, even after trying to schedule 407 // an evacuation pause, allocate_new_tlab() will return NULL, 408 // whereas mem_allocate() will attempt a heap expansion and/or 409 // schedule a Full GC. 410 // 411 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 412 // should never be called with word_size being humongous. All 413 // humongous allocation requests should go to mem_allocate() which 414 // will satisfy them with a special path. 415 416 virtual HeapWord* allocate_new_tlab(size_t min_size, 417 size_t requested_size, 418 size_t* actual_size); 419 420 virtual HeapWord* mem_allocate(size_t word_size, 421 bool* gc_overhead_limit_was_exceeded); 422 423 // First-level mutator allocation attempt: try to allocate out of 424 // the mutator alloc region without taking the Heap_lock. This 425 // should only be used for non-humongous allocations. 426 inline HeapWord* attempt_allocation(size_t min_word_size, 427 size_t desired_word_size, 428 size_t* actual_word_size); 429 430 // Second-level mutator allocation attempt: take the Heap_lock and 431 // retry the allocation attempt, potentially scheduling a GC 432 // pause. This should only be used for non-humongous allocations. 433 HeapWord* attempt_allocation_slow(size_t word_size); 434 435 // Takes the Heap_lock and attempts a humongous allocation. It can 436 // potentially schedule a GC pause. 437 HeapWord* attempt_allocation_humongous(size_t word_size); 438 439 // Allocation attempt that should be called during safepoints (e.g., 440 // at the end of a successful GC). expect_null_mutator_alloc_region 441 // specifies whether the mutator alloc region is expected to be NULL 442 // or not. 443 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 444 bool expect_null_mutator_alloc_region); 445 446 // These methods are the "callbacks" from the G1AllocRegion class. 447 448 // For mutator alloc regions. 449 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 450 void retire_mutator_alloc_region(HeapRegion* alloc_region, 451 size_t allocated_bytes); 452 453 // For GC alloc regions. 454 bool has_more_regions(InCSetState dest); 455 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest); 456 void retire_gc_alloc_region(HeapRegion* alloc_region, 457 size_t allocated_bytes, InCSetState dest); 458 459 // - if explicit_gc is true, the GC is for a System.gc() etc, 460 // otherwise it's for a failed allocation. 461 // - if clear_all_soft_refs is true, all soft references should be 462 // cleared during the GC. 463 // - it returns false if it is unable to do the collection due to the 464 // GC locker being active, true otherwise. 465 bool do_full_collection(bool explicit_gc, 466 bool clear_all_soft_refs); 467 468 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 469 virtual void do_full_collection(bool clear_all_soft_refs); 470 471 // Resize the heap if necessary after a full collection. 472 void resize_if_necessary_after_full_collection(); 473 474 // Callback from VM_G1CollectForAllocation operation. 475 // This function does everything necessary/possible to satisfy a 476 // failed allocation request (including collection, expansion, etc.) 477 HeapWord* satisfy_failed_allocation(size_t word_size, 478 bool* succeeded); 479 // Internal helpers used during full GC to split it up to 480 // increase readability. 481 void abort_concurrent_cycle(); 482 void verify_before_full_collection(bool explicit_gc); 483 void prepare_heap_for_full_collection(); 484 void prepare_heap_for_mutators(); 485 void abort_refinement(); 486 void verify_after_full_collection(); 487 void print_heap_after_full_collection(G1HeapTransition* heap_transition); 488 489 // Helper method for satisfy_failed_allocation() 490 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 491 bool do_gc, 492 bool clear_all_soft_refs, 493 bool expect_null_mutator_alloc_region, 494 bool* gc_succeeded); 495 496 // Attempting to expand the heap sufficiently 497 // to support an allocation of the given "word_size". If 498 // successful, perform the allocation and return the address of the 499 // allocated block, or else "NULL". 500 HeapWord* expand_and_allocate(size_t word_size); 501 502 // Process any reference objects discovered. 503 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 504 505 // If during an initial mark pause we may install a pending list head which is not 506 // otherwise reachable ensure that it is marked in the bitmap for concurrent marking 507 // to discover. 508 void make_pending_list_reachable(); 509 510 // Merges the information gathered on a per-thread basis for all worker threads 511 // during GC into global variables. 512 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states); 513 public: 514 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; } 515 516 WorkGang* workers() const { return _workers; } 517 518 G1Allocator* allocator() { 519 return _allocator; 520 } 521 522 G1HeapVerifier* verifier() { 523 return _verifier; 524 } 525 526 G1MonitoringSupport* g1mm() { 527 assert(_g1mm != NULL, "should have been initialized"); 528 return _g1mm; 529 } 530 531 // Expand the garbage-first heap by at least the given size (in bytes!). 532 // Returns true if the heap was expanded by the requested amount; 533 // false otherwise. 534 // (Rounds up to a HeapRegion boundary.) 535 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL); 536 537 // Returns the PLAB statistics for a given destination. 538 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 539 540 // Determines PLAB size for a given destination. 541 inline size_t desired_plab_sz(InCSetState dest); 542 543 // Do anything common to GC's. 544 void gc_prologue(bool full); 545 void gc_epilogue(bool full); 546 547 // Does the given region fulfill remembered set based eager reclaim candidate requirements? 548 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const; 549 550 // Modify the reclaim candidate set and test for presence. 551 // These are only valid for starts_humongous regions. 552 inline void set_humongous_reclaim_candidate(uint region, bool value); 553 inline bool is_humongous_reclaim_candidate(uint region); 554 555 // Remove from the reclaim candidate set. Also remove from the 556 // collection set so that later encounters avoid the slow path. 557 inline void set_humongous_is_live(oop obj); 558 559 // Register the given region to be part of the collection set. 560 inline void register_humongous_region_with_cset(uint index); 561 // Register regions with humongous objects (actually on the start region) in 562 // the in_cset_fast_test table. 563 void register_humongous_regions_with_cset(); 564 // We register a region with the fast "in collection set" test. We 565 // simply set to true the array slot corresponding to this region. 566 void register_young_region_with_cset(HeapRegion* r) { 567 _in_cset_fast_test.set_in_young(r->hrm_index()); 568 } 569 void register_old_region_with_cset(HeapRegion* r) { 570 _in_cset_fast_test.set_in_old(r->hrm_index()); 571 } 572 void clear_in_cset(const HeapRegion* hr) { 573 _in_cset_fast_test.clear(hr); 574 } 575 576 void clear_cset_fast_test() { 577 _in_cset_fast_test.clear(); 578 } 579 580 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 581 582 // This is called at the start of either a concurrent cycle or a Full 583 // GC to update the number of old marking cycles started. 584 void increment_old_marking_cycles_started(); 585 586 // This is called at the end of either a concurrent cycle or a Full 587 // GC to update the number of old marking cycles completed. Those two 588 // can happen in a nested fashion, i.e., we start a concurrent 589 // cycle, a Full GC happens half-way through it which ends first, 590 // and then the cycle notices that a Full GC happened and ends 591 // too. The concurrent parameter is a boolean to help us do a bit 592 // tighter consistency checking in the method. If concurrent is 593 // false, the caller is the inner caller in the nesting (i.e., the 594 // Full GC). If concurrent is true, the caller is the outer caller 595 // in this nesting (i.e., the concurrent cycle). Further nesting is 596 // not currently supported. The end of this call also notifies 597 // the FullGCCount_lock in case a Java thread is waiting for a full 598 // GC to happen (e.g., it called System.gc() with 599 // +ExplicitGCInvokesConcurrent). 600 void increment_old_marking_cycles_completed(bool concurrent); 601 602 uint old_marking_cycles_completed() { 603 return _old_marking_cycles_completed; 604 } 605 606 G1HRPrinter* hr_printer() { return &_hr_printer; } 607 608 // Allocates a new heap region instance. 609 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 610 611 // Allocate the highest free region in the reserved heap. This will commit 612 // regions as necessary. 613 HeapRegion* alloc_highest_free_region(); 614 615 // Frees a non-humongous region by initializing its contents and 616 // adding it to the free list that's passed as a parameter (this is 617 // usually a local list which will be appended to the master free 618 // list later). The used bytes of freed regions are accumulated in 619 // pre_used. If skip_remset is true, the region's RSet will not be freed 620 // up. If skip_hot_card_cache is true, the region's hot card cache will not 621 // be freed up. The assumption is that this will be done later. 622 // The locked parameter indicates if the caller has already taken 623 // care of proper synchronization. This may allow some optimizations. 624 void free_region(HeapRegion* hr, 625 FreeRegionList* free_list, 626 bool skip_remset, 627 bool skip_hot_card_cache = false, 628 bool locked = false); 629 630 // It dirties the cards that cover the block so that the post 631 // write barrier never queues anything when updating objects on this 632 // block. It is assumed (and in fact we assert) that the block 633 // belongs to a young region. 634 inline void dirty_young_block(HeapWord* start, size_t word_size); 635 636 // Frees a humongous region by collapsing it into individual regions 637 // and calling free_region() for each of them. The freed regions 638 // will be added to the free list that's passed as a parameter (this 639 // is usually a local list which will be appended to the master free 640 // list later). 641 // The method assumes that only a single thread is ever calling 642 // this for a particular region at once. 643 void free_humongous_region(HeapRegion* hr, 644 FreeRegionList* free_list); 645 646 // Facility for allocating in 'archive' regions in high heap memory and 647 // recording the allocated ranges. These should all be called from the 648 // VM thread at safepoints, without the heap lock held. They can be used 649 // to create and archive a set of heap regions which can be mapped at the 650 // same fixed addresses in a subsequent JVM invocation. 651 void begin_archive_alloc_range(bool open = false); 652 653 // Check if the requested size would be too large for an archive allocation. 654 bool is_archive_alloc_too_large(size_t word_size); 655 656 // Allocate memory of the requested size from the archive region. This will 657 // return NULL if the size is too large or if no memory is available. It 658 // does not trigger a garbage collection. 659 HeapWord* archive_mem_allocate(size_t word_size); 660 661 // Optionally aligns the end address and returns the allocated ranges in 662 // an array of MemRegions in order of ascending addresses. 663 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 664 size_t end_alignment_in_bytes = 0); 665 666 // Facility for allocating a fixed range within the heap and marking 667 // the containing regions as 'archive'. For use at JVM init time, when the 668 // caller may mmap archived heap data at the specified range(s). 669 // Verify that the MemRegions specified in the argument array are within the 670 // reserved heap. 671 bool check_archive_addresses(MemRegion* range, size_t count); 672 673 // Commit the appropriate G1 regions containing the specified MemRegions 674 // and mark them as 'archive' regions. The regions in the array must be 675 // non-overlapping and in order of ascending address. 676 bool alloc_archive_regions(MemRegion* range, size_t count, bool open); 677 678 // Insert any required filler objects in the G1 regions around the specified 679 // ranges to make the regions parseable. This must be called after 680 // alloc_archive_regions, and after class loading has occurred. 681 void fill_archive_regions(MemRegion* range, size_t count); 682 683 // For each of the specified MemRegions, uncommit the containing G1 regions 684 // which had been allocated by alloc_archive_regions. This should be called 685 // rather than fill_archive_regions at JVM init time if the archive file 686 // mapping failed, with the same non-overlapping and sorted MemRegion array. 687 void dealloc_archive_regions(MemRegion* range, size_t count); 688 689 oop materialize_archived_object(oop obj); 690 691 private: 692 693 // Shrink the garbage-first heap by at most the given size (in bytes!). 694 // (Rounds down to a HeapRegion boundary.) 695 void shrink(size_t expand_bytes); 696 void shrink_helper(size_t expand_bytes); 697 698 #if TASKQUEUE_STATS 699 static void print_taskqueue_stats_hdr(outputStream* const st); 700 void print_taskqueue_stats() const; 701 void reset_taskqueue_stats(); 702 #endif // TASKQUEUE_STATS 703 704 // Schedule the VM operation that will do an evacuation pause to 705 // satisfy an allocation request of word_size. *succeeded will 706 // return whether the VM operation was successful (it did do an 707 // evacuation pause) or not (another thread beat us to it or the GC 708 // locker was active). Given that we should not be holding the 709 // Heap_lock when we enter this method, we will pass the 710 // gc_count_before (i.e., total_collections()) as a parameter since 711 // it has to be read while holding the Heap_lock. Currently, both 712 // methods that call do_collection_pause() release the Heap_lock 713 // before the call, so it's easy to read gc_count_before just before. 714 HeapWord* do_collection_pause(size_t word_size, 715 uint gc_count_before, 716 bool* succeeded, 717 GCCause::Cause gc_cause); 718 719 void wait_for_root_region_scanning(); 720 721 // The guts of the incremental collection pause, executed by the vm 722 // thread. It returns false if it is unable to do the collection due 723 // to the GC locker being active, true otherwise 724 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 725 726 // Actually do the work of evacuating the collection set. 727 void evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states); 728 729 void pre_evacuate_collection_set(); 730 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 731 732 // Print the header for the per-thread termination statistics. 733 static void print_termination_stats_hdr(); 734 // Print actual per-thread termination statistics. 735 void print_termination_stats(uint worker_id, 736 double elapsed_ms, 737 double strong_roots_ms, 738 double term_ms, 739 size_t term_attempts, 740 size_t alloc_buffer_waste, 741 size_t undo_waste) const; 742 // Update object copying statistics. 743 void record_obj_copy_mem_stats(); 744 745 // The hot card cache for remembered set insertion optimization. 746 G1HotCardCache* _hot_card_cache; 747 748 // The g1 remembered set of the heap. 749 G1RemSet* _g1_rem_set; 750 751 // A set of cards that cover the objects for which the Rsets should be updated 752 // concurrently after the collection. 753 DirtyCardQueueSet _dirty_card_queue_set; 754 755 // After a collection pause, convert the regions in the collection set into free 756 // regions. 757 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 758 759 // Abandon the current collection set without recording policy 760 // statistics or updating free lists. 761 void abandon_collection_set(G1CollectionSet* collection_set); 762 763 // The concurrent marker (and the thread it runs in.) 764 G1ConcurrentMark* _cm; 765 G1ConcurrentMarkThread* _cm_thread; 766 767 // The concurrent refiner. 768 G1ConcurrentRefine* _cr; 769 770 // The parallel task queues 771 RefToScanQueueSet *_task_queues; 772 773 // True iff a evacuation has failed in the current collection. 774 bool _evacuation_failed; 775 776 EvacuationFailedInfo* _evacuation_failed_info_array; 777 778 // Failed evacuations cause some logical from-space objects to have 779 // forwarding pointers to themselves. Reset them. 780 void remove_self_forwarding_pointers(); 781 782 // Restore the objects in the regions in the collection set after an 783 // evacuation failure. 784 void restore_after_evac_failure(); 785 786 PreservedMarksSet _preserved_marks_set; 787 788 // Preserve the mark of "obj", if necessary, in preparation for its mark 789 // word being overwritten with a self-forwarding-pointer. 790 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 791 792 #ifndef PRODUCT 793 // Support for forcing evacuation failures. Analogous to 794 // PromotionFailureALot for the other collectors. 795 796 // Records whether G1EvacuationFailureALot should be in effect 797 // for the current GC 798 bool _evacuation_failure_alot_for_current_gc; 799 800 // Used to record the GC number for interval checking when 801 // determining whether G1EvaucationFailureALot is in effect 802 // for the current GC. 803 size_t _evacuation_failure_alot_gc_number; 804 805 // Count of the number of evacuations between failures. 806 volatile size_t _evacuation_failure_alot_count; 807 808 // Set whether G1EvacuationFailureALot should be in effect 809 // for the current GC (based upon the type of GC and which 810 // command line flags are set); 811 inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc, 812 bool during_initial_mark, 813 bool mark_or_rebuild_in_progress); 814 815 inline void set_evacuation_failure_alot_for_current_gc(); 816 817 // Return true if it's time to cause an evacuation failure. 818 inline bool evacuation_should_fail(); 819 820 // Reset the G1EvacuationFailureALot counters. Should be called at 821 // the end of an evacuation pause in which an evacuation failure occurred. 822 inline void reset_evacuation_should_fail(); 823 #endif // !PRODUCT 824 825 // ("Weak") Reference processing support. 826 // 827 // G1 has 2 instances of the reference processor class. One 828 // (_ref_processor_cm) handles reference object discovery 829 // and subsequent processing during concurrent marking cycles. 830 // 831 // The other (_ref_processor_stw) handles reference object 832 // discovery and processing during full GCs and incremental 833 // evacuation pauses. 834 // 835 // During an incremental pause, reference discovery will be 836 // temporarily disabled for _ref_processor_cm and will be 837 // enabled for _ref_processor_stw. At the end of the evacuation 838 // pause references discovered by _ref_processor_stw will be 839 // processed and discovery will be disabled. The previous 840 // setting for reference object discovery for _ref_processor_cm 841 // will be re-instated. 842 // 843 // At the start of marking: 844 // * Discovery by the CM ref processor is verified to be inactive 845 // and it's discovered lists are empty. 846 // * Discovery by the CM ref processor is then enabled. 847 // 848 // At the end of marking: 849 // * Any references on the CM ref processor's discovered 850 // lists are processed (possibly MT). 851 // 852 // At the start of full GC we: 853 // * Disable discovery by the CM ref processor and 854 // empty CM ref processor's discovered lists 855 // (without processing any entries). 856 // * Verify that the STW ref processor is inactive and it's 857 // discovered lists are empty. 858 // * Temporarily set STW ref processor discovery as single threaded. 859 // * Temporarily clear the STW ref processor's _is_alive_non_header 860 // field. 861 // * Finally enable discovery by the STW ref processor. 862 // 863 // The STW ref processor is used to record any discovered 864 // references during the full GC. 865 // 866 // At the end of a full GC we: 867 // * Enqueue any reference objects discovered by the STW ref processor 868 // that have non-live referents. This has the side-effect of 869 // making the STW ref processor inactive by disabling discovery. 870 // * Verify that the CM ref processor is still inactive 871 // and no references have been placed on it's discovered 872 // lists (also checked as a precondition during initial marking). 873 874 // The (stw) reference processor... 875 ReferenceProcessor* _ref_processor_stw; 876 877 // During reference object discovery, the _is_alive_non_header 878 // closure (if non-null) is applied to the referent object to 879 // determine whether the referent is live. If so then the 880 // reference object does not need to be 'discovered' and can 881 // be treated as a regular oop. This has the benefit of reducing 882 // the number of 'discovered' reference objects that need to 883 // be processed. 884 // 885 // Instance of the is_alive closure for embedding into the 886 // STW reference processor as the _is_alive_non_header field. 887 // Supplying a value for the _is_alive_non_header field is 888 // optional but doing so prevents unnecessary additions to 889 // the discovered lists during reference discovery. 890 G1STWIsAliveClosure _is_alive_closure_stw; 891 892 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw; 893 894 // The (concurrent marking) reference processor... 895 ReferenceProcessor* _ref_processor_cm; 896 897 // Instance of the concurrent mark is_alive closure for embedding 898 // into the Concurrent Marking reference processor as the 899 // _is_alive_non_header field. Supplying a value for the 900 // _is_alive_non_header field is optional but doing so prevents 901 // unnecessary additions to the discovered lists during reference 902 // discovery. 903 G1CMIsAliveClosure _is_alive_closure_cm; 904 905 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm; 906 public: 907 908 RefToScanQueue *task_queue(uint i) const; 909 910 uint num_task_queues() const; 911 912 // A set of cards where updates happened during the GC 913 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 914 915 // Create a G1CollectedHeap with the specified policy. 916 // Must call the initialize method afterwards. 917 // May not return if something goes wrong. 918 G1CollectedHeap(G1CollectorPolicy* policy); 919 920 private: 921 jint initialize_concurrent_refinement(); 922 jint initialize_young_gen_sampling_thread(); 923 public: 924 // Initialize the G1CollectedHeap to have the initial and 925 // maximum sizes and remembered and barrier sets 926 // specified by the policy object. 927 jint initialize(); 928 929 virtual void stop(); 930 virtual void safepoint_synchronize_begin(); 931 virtual void safepoint_synchronize_end(); 932 933 // Return the (conservative) maximum heap alignment for any G1 heap 934 static size_t conservative_max_heap_alignment(); 935 936 // Does operations required after initialization has been done. 937 void post_initialize(); 938 939 // Initialize weak reference processing. 940 void ref_processing_init(); 941 942 virtual Name kind() const { 943 return CollectedHeap::G1; 944 } 945 946 virtual const char* name() const { 947 return "G1"; 948 } 949 950 const G1CollectorState* collector_state() const { return &_collector_state; } 951 G1CollectorState* collector_state() { return &_collector_state; } 952 953 // The current policy object for the collector. 954 G1Policy* g1_policy() const { return _g1_policy; } 955 956 const G1CollectionSet* collection_set() const { return &_collection_set; } 957 G1CollectionSet* collection_set() { return &_collection_set; } 958 959 virtual CollectorPolicy* collector_policy() const; 960 961 virtual SoftRefPolicy* soft_ref_policy(); 962 963 virtual void initialize_serviceability(); 964 virtual MemoryUsage memory_usage(); 965 virtual GrowableArray<GCMemoryManager*> memory_managers(); 966 virtual GrowableArray<MemoryPool*> memory_pools(); 967 968 // The rem set and barrier set. 969 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 970 971 // Try to minimize the remembered set. 972 void scrub_rem_set(); 973 974 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 975 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i); 976 977 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. 978 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i); 979 980 // The shared block offset table array. 981 G1BlockOffsetTable* bot() const { return _bot; } 982 983 // Reference Processing accessors 984 985 // The STW reference processor.... 986 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 987 988 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 989 990 // The Concurrent Marking reference processor... 991 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 992 993 size_t unused_committed_regions_in_bytes() const; 994 virtual size_t capacity() const; 995 virtual size_t used() const; 996 // This should be called when we're not holding the heap lock. The 997 // result might be a bit inaccurate. 998 size_t used_unlocked() const; 999 size_t recalculate_used() const; 1000 1001 // These virtual functions do the actual allocation. 1002 // Some heaps may offer a contiguous region for shared non-blocking 1003 // allocation, via inlined code (by exporting the address of the top and 1004 // end fields defining the extent of the contiguous allocation region.) 1005 // But G1CollectedHeap doesn't yet support this. 1006 1007 virtual bool is_maximal_no_gc() const { 1008 return _hrm.available() == 0; 1009 } 1010 1011 // Returns whether there are any regions left in the heap for allocation. 1012 bool has_regions_left_for_allocation() const { 1013 return !is_maximal_no_gc() || num_free_regions() != 0; 1014 } 1015 1016 // The current number of regions in the heap. 1017 uint num_regions() const { return _hrm.length(); } 1018 1019 // The max number of regions in the heap. 1020 uint max_regions() const { return _hrm.max_length(); } 1021 1022 // The number of regions that are completely free. 1023 uint num_free_regions() const { return _hrm.num_free_regions(); } 1024 1025 MemoryUsage get_auxiliary_data_memory_usage() const { 1026 return _hrm.get_auxiliary_data_memory_usage(); 1027 } 1028 1029 // The number of regions that are not completely free. 1030 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1031 1032 #ifdef ASSERT 1033 bool is_on_master_free_list(HeapRegion* hr) { 1034 return _hrm.is_free(hr); 1035 } 1036 #endif // ASSERT 1037 1038 inline void old_set_add(HeapRegion* hr); 1039 inline void old_set_remove(HeapRegion* hr); 1040 1041 inline void archive_set_add(HeapRegion* hr); 1042 1043 size_t non_young_capacity_bytes() { 1044 return (old_regions_count() + _archive_set.length() + humongous_regions_count()) * HeapRegion::GrainBytes; 1045 } 1046 1047 // Determine whether the given region is one that we are using as an 1048 // old GC alloc region. 1049 bool is_old_gc_alloc_region(HeapRegion* hr); 1050 1051 // Perform a collection of the heap; intended for use in implementing 1052 // "System.gc". This probably implies as full a collection as the 1053 // "CollectedHeap" supports. 1054 virtual void collect(GCCause::Cause cause); 1055 1056 // True iff an evacuation has failed in the most-recent collection. 1057 bool evacuation_failed() { return _evacuation_failed; } 1058 1059 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed); 1060 void prepend_to_freelist(FreeRegionList* list); 1061 void decrement_summary_bytes(size_t bytes); 1062 1063 virtual bool is_in(const void* p) const; 1064 #ifdef ASSERT 1065 // Returns whether p is in one of the available areas of the heap. Slow but 1066 // extensive version. 1067 bool is_in_exact(const void* p) const; 1068 #endif 1069 1070 // Return "TRUE" iff the given object address is within the collection 1071 // set. Assumes that the reference points into the heap. 1072 inline bool is_in_cset(const HeapRegion *hr); 1073 inline bool is_in_cset(oop obj); 1074 inline bool is_in_cset(HeapWord* addr); 1075 1076 inline bool is_in_cset_or_humongous(const oop obj); 1077 1078 private: 1079 // This array is used for a quick test on whether a reference points into 1080 // the collection set or not. Each of the array's elements denotes whether the 1081 // corresponding region is in the collection set or not. 1082 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1083 1084 public: 1085 1086 inline InCSetState in_cset_state(const oop obj); 1087 1088 // Return "TRUE" iff the given object address is in the reserved 1089 // region of g1. 1090 bool is_in_g1_reserved(const void* p) const { 1091 return _hrm.reserved().contains(p); 1092 } 1093 1094 // Returns a MemRegion that corresponds to the space that has been 1095 // reserved for the heap 1096 MemRegion g1_reserved() const { 1097 return _hrm.reserved(); 1098 } 1099 1100 virtual bool is_in_closed_subset(const void* p) const; 1101 1102 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; } 1103 1104 G1CardTable* card_table() const { 1105 return _card_table; 1106 } 1107 1108 // Iteration functions. 1109 1110 // Iterate over all objects, calling "cl.do_object" on each. 1111 virtual void object_iterate(ObjectClosure* cl); 1112 1113 virtual void safe_object_iterate(ObjectClosure* cl) { 1114 object_iterate(cl); 1115 } 1116 1117 // Iterate over heap regions, in address order, terminating the 1118 // iteration early if the "do_heap_region" method returns "true". 1119 void heap_region_iterate(HeapRegionClosure* blk) const; 1120 1121 // Return the region with the given index. It assumes the index is valid. 1122 inline HeapRegion* region_at(uint index) const; 1123 inline HeapRegion* region_at_or_null(uint index) const; 1124 1125 // Return the next region (by index) that is part of the same 1126 // humongous object that hr is part of. 1127 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1128 1129 // Calculate the region index of the given address. Given address must be 1130 // within the heap. 1131 inline uint addr_to_region(HeapWord* addr) const; 1132 1133 inline HeapWord* bottom_addr_for_region(uint index) const; 1134 1135 // Two functions to iterate over the heap regions in parallel. Threads 1136 // compete using the HeapRegionClaimer to claim the regions before 1137 // applying the closure on them. 1138 // The _from_worker_offset version uses the HeapRegionClaimer and 1139 // the worker id to calculate a start offset to prevent all workers to 1140 // start from the point. 1141 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 1142 HeapRegionClaimer* hrclaimer, 1143 uint worker_id) const; 1144 1145 void heap_region_par_iterate_from_start(HeapRegionClosure* cl, 1146 HeapRegionClaimer* hrclaimer) const; 1147 1148 // Iterate over the regions (if any) in the current collection set. 1149 void collection_set_iterate(HeapRegionClosure* blk); 1150 1151 // Iterate over the regions (if any) in the current collection set. Starts the 1152 // iteration over the entire collection set so that the start regions of a given 1153 // worker id over the set active_workers are evenly spread across the set of 1154 // collection set regions. 1155 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id); 1156 1157 // Returns the HeapRegion that contains addr. addr must not be NULL. 1158 template <class T> 1159 inline HeapRegion* heap_region_containing(const T addr) const; 1160 1161 // Returns the HeapRegion that contains addr, or NULL if that is an uncommitted 1162 // region. addr must not be NULL. 1163 template <class T> 1164 inline HeapRegion* heap_region_containing_or_null(const T addr) const; 1165 1166 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1167 // each address in the (reserved) heap is a member of exactly 1168 // one block. The defining characteristic of a block is that it is 1169 // possible to find its size, and thus to progress forward to the next 1170 // block. (Blocks may be of different sizes.) Thus, blocks may 1171 // represent Java objects, or they might be free blocks in a 1172 // free-list-based heap (or subheap), as long as the two kinds are 1173 // distinguishable and the size of each is determinable. 1174 1175 // Returns the address of the start of the "block" that contains the 1176 // address "addr". We say "blocks" instead of "object" since some heaps 1177 // may not pack objects densely; a chunk may either be an object or a 1178 // non-object. 1179 virtual HeapWord* block_start(const void* addr) const; 1180 1181 // Requires "addr" to be the start of a chunk, and returns its size. 1182 // "addr + size" is required to be the start of a new chunk, or the end 1183 // of the active area of the heap. 1184 virtual size_t block_size(const HeapWord* addr) const; 1185 1186 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1187 // the block is an object. 1188 virtual bool block_is_obj(const HeapWord* addr) const; 1189 1190 // Section on thread-local allocation buffers (TLABs) 1191 // See CollectedHeap for semantics. 1192 1193 bool supports_tlab_allocation() const; 1194 size_t tlab_capacity(Thread* ignored) const; 1195 size_t tlab_used(Thread* ignored) const; 1196 size_t max_tlab_size() const; 1197 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1198 1199 inline bool is_in_young(const oop obj); 1200 1201 // Returns "true" iff the given word_size is "very large". 1202 static bool is_humongous(size_t word_size) { 1203 // Note this has to be strictly greater-than as the TLABs 1204 // are capped at the humongous threshold and we want to 1205 // ensure that we don't try to allocate a TLAB as 1206 // humongous and that we don't allocate a humongous 1207 // object in a TLAB. 1208 return word_size > _humongous_object_threshold_in_words; 1209 } 1210 1211 // Returns the humongous threshold for a specific region size 1212 static size_t humongous_threshold_for(size_t region_size) { 1213 return (region_size / 2); 1214 } 1215 1216 // Returns the number of regions the humongous object of the given word size 1217 // requires. 1218 static size_t humongous_obj_size_in_regions(size_t word_size); 1219 1220 // Print the maximum heap capacity. 1221 virtual size_t max_capacity() const; 1222 1223 virtual jlong millis_since_last_gc(); 1224 1225 1226 // Convenience function to be used in situations where the heap type can be 1227 // asserted to be this type. 1228 static G1CollectedHeap* heap(); 1229 1230 void set_region_short_lived_locked(HeapRegion* hr); 1231 // add appropriate methods for any other surv rate groups 1232 1233 const G1SurvivorRegions* survivor() const { return &_survivor; } 1234 1235 uint eden_regions_count() const { return _eden.length(); } 1236 uint survivor_regions_count() const { return _survivor.length(); } 1237 uint young_regions_count() const { return _eden.length() + _survivor.length(); } 1238 uint old_regions_count() const { return _old_set.length(); } 1239 uint archive_regions_count() const { return _archive_set.length(); } 1240 uint humongous_regions_count() const { return _humongous_set.length(); } 1241 1242 #ifdef ASSERT 1243 bool check_young_list_empty(); 1244 #endif 1245 1246 // *** Stuff related to concurrent marking. It's not clear to me that so 1247 // many of these need to be public. 1248 1249 // The functions below are helper functions that a subclass of 1250 // "CollectedHeap" can use in the implementation of its virtual 1251 // functions. 1252 // This performs a concurrent marking of the live objects in a 1253 // bitmap off to the side. 1254 void do_concurrent_mark(); 1255 1256 bool is_marked_next(oop obj) const; 1257 1258 // Determine if an object is dead, given the object and also 1259 // the region to which the object belongs. An object is dead 1260 // iff a) it was not allocated since the last mark, b) it 1261 // is not marked, and c) it is not in an archive region. 1262 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1263 return 1264 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) && 1265 !hr->is_archive(); 1266 } 1267 1268 // This function returns true when an object has been 1269 // around since the previous marking and hasn't yet 1270 // been marked during this marking, and is not in an archive region. 1271 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1272 return 1273 !hr->obj_allocated_since_next_marking(obj) && 1274 !is_marked_next(obj) && 1275 !hr->is_archive(); 1276 } 1277 1278 // Determine if an object is dead, given only the object itself. 1279 // This will find the region to which the object belongs and 1280 // then call the region version of the same function. 1281 1282 // Added if it is NULL it isn't dead. 1283 1284 inline bool is_obj_dead(const oop obj) const; 1285 1286 inline bool is_obj_ill(const oop obj) const; 1287 1288 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const; 1289 inline bool is_obj_dead_full(const oop obj) const; 1290 1291 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1292 1293 // Refinement 1294 1295 G1ConcurrentRefine* concurrent_refine() const { return _cr; } 1296 1297 // Optimized nmethod scanning support routines 1298 1299 // Is an oop scavengeable 1300 virtual bool is_scavengable(oop obj); 1301 1302 // Register the given nmethod with the G1 heap. 1303 virtual void register_nmethod(nmethod* nm); 1304 1305 // Unregister the given nmethod from the G1 heap. 1306 virtual void unregister_nmethod(nmethod* nm); 1307 1308 // Free up superfluous code root memory. 1309 void purge_code_root_memory(); 1310 1311 // Rebuild the strong code root lists for each region 1312 // after a full GC. 1313 void rebuild_strong_code_roots(); 1314 1315 // Partial cleaning used when class unloading is disabled. 1316 // Let the caller choose what structures to clean out: 1317 // - StringTable 1318 // - StringDeduplication structures 1319 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_string_dedup); 1320 1321 // Complete cleaning used when class unloading is enabled. 1322 // Cleans out all structures handled by partial_cleaning and also the CodeCache. 1323 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); 1324 1325 // Redirty logged cards in the refinement queue. 1326 void redirty_logged_cards(); 1327 // Verification 1328 1329 // Deduplicate the string 1330 virtual void deduplicate_string(oop str); 1331 1332 // Perform any cleanup actions necessary before allowing a verification. 1333 virtual void prepare_for_verify(); 1334 1335 // Perform verification. 1336 1337 // vo == UsePrevMarking -> use "prev" marking information, 1338 // vo == UseNextMarking -> use "next" marking information 1339 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS 1340 // 1341 // NOTE: Only the "prev" marking information is guaranteed to be 1342 // consistent most of the time, so most calls to this should use 1343 // vo == UsePrevMarking. 1344 // Currently, there is only one case where this is called with 1345 // vo == UseNextMarking, which is to verify the "next" marking 1346 // information at the end of remark. 1347 // Currently there is only one place where this is called with 1348 // vo == UseFullMarking, which is to verify the marking during a 1349 // full GC. 1350 void verify(VerifyOption vo); 1351 1352 // WhiteBox testing support. 1353 virtual bool supports_concurrent_phase_control() const; 1354 virtual const char* const* concurrent_phases() const; 1355 virtual bool request_concurrent_phase(const char* phase); 1356 1357 virtual WorkGang* get_safepoint_workers() { return _workers; } 1358 1359 // The methods below are here for convenience and dispatch the 1360 // appropriate method depending on value of the given VerifyOption 1361 // parameter. The values for that parameter, and their meanings, 1362 // are the same as those above. 1363 1364 bool is_obj_dead_cond(const oop obj, 1365 const HeapRegion* hr, 1366 const VerifyOption vo) const; 1367 1368 bool is_obj_dead_cond(const oop obj, 1369 const VerifyOption vo) const; 1370 1371 G1HeapSummary create_g1_heap_summary(); 1372 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1373 1374 // Printing 1375 private: 1376 void print_heap_regions() const; 1377 void print_regions_on(outputStream* st) const; 1378 1379 public: 1380 virtual void print_on(outputStream* st) const; 1381 virtual void print_extended_on(outputStream* st) const; 1382 virtual void print_on_error(outputStream* st) const; 1383 1384 virtual void print_gc_threads_on(outputStream* st) const; 1385 virtual void gc_threads_do(ThreadClosure* tc) const; 1386 1387 // Override 1388 void print_tracing_info() const; 1389 1390 // The following two methods are helpful for debugging RSet issues. 1391 void print_cset_rsets() PRODUCT_RETURN; 1392 void print_all_rsets() PRODUCT_RETURN; 1393 1394 size_t pending_card_num(); 1395 }; 1396 1397 class G1ParEvacuateFollowersClosure : public VoidClosure { 1398 private: 1399 double _start_term; 1400 double _term_time; 1401 size_t _term_attempts; 1402 1403 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 1404 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 1405 protected: 1406 G1CollectedHeap* _g1h; 1407 G1ParScanThreadState* _par_scan_state; 1408 RefToScanQueueSet* _queues; 1409 ParallelTaskTerminator* _terminator; 1410 1411 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 1412 RefToScanQueueSet* queues() { return _queues; } 1413 ParallelTaskTerminator* terminator() { return _terminator; } 1414 1415 public: 1416 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 1417 G1ParScanThreadState* par_scan_state, 1418 RefToScanQueueSet* queues, 1419 ParallelTaskTerminator* terminator) 1420 : _start_term(0.0), _term_time(0.0), _term_attempts(0), 1421 _g1h(g1h), _par_scan_state(par_scan_state), 1422 _queues(queues), _terminator(terminator) {} 1423 1424 void do_void(); 1425 1426 double term_time() const { return _term_time; } 1427 size_t term_attempts() const { return _term_attempts; } 1428 1429 private: 1430 inline bool offer_termination(); 1431 }; 1432 1433 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP