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 "services/memoryManager.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 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 Ticks; 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 GCMemoryManager _memory_manager; 165 GCMemoryManager _full_gc_memory_manager; 166 167 MemoryPool* _eden_pool; 168 MemoryPool* _survivor_pool; 169 MemoryPool* _old_pool; 170 171 static size_t _humongous_object_threshold_in_words; 172 173 // It keeps track of the old regions. 174 HeapRegionSet _old_set; 175 176 // It keeps track of the humongous regions. 177 HeapRegionSet _humongous_set; 178 179 virtual void initialize_serviceability(); 180 181 void eagerly_reclaim_humongous_regions(); 182 // Start a new incremental collection set for the next pause. 183 void start_new_collection_set(); 184 185 // The number of regions we could create by expansion. 186 uint _expansion_regions; 187 188 // The block offset table for the G1 heap. 189 G1BlockOffsetTable* _bot; 190 191 // Tears down the region sets / lists so that they are empty and the 192 // regions on the heap do not belong to a region set / list. The 193 // only exception is the humongous set which we leave unaltered. If 194 // free_list_only is true, it will only tear down the master free 195 // list. It is called before a Full GC (free_list_only == false) or 196 // before heap shrinking (free_list_only == true). 197 void tear_down_region_sets(bool free_list_only); 198 199 // Rebuilds the region sets / lists so that they are repopulated to 200 // reflect the contents of the heap. The only exception is the 201 // humongous set which was not torn down in the first place. If 202 // free_list_only is true, it will only rebuild the master free 203 // list. It is called after a Full GC (free_list_only == false) or 204 // after heap shrinking (free_list_only == true). 205 void rebuild_region_sets(bool free_list_only); 206 207 // Callback for region mapping changed events. 208 G1RegionMappingChangedListener _listener; 209 210 // The sequence of all heap regions in the heap. 211 HeapRegionManager _hrm; 212 213 // Manages all allocations with regions except humongous object allocations. 214 G1Allocator* _allocator; 215 216 // Manages all heap verification. 217 G1HeapVerifier* _verifier; 218 219 // Outside of GC pauses, the number of bytes used in all regions other 220 // than the current allocation region(s). 221 size_t _summary_bytes_used; 222 223 void increase_used(size_t bytes); 224 void decrease_used(size_t bytes); 225 226 void set_used(size_t bytes); 227 228 // Class that handles archive allocation ranges. 229 G1ArchiveAllocator* _archive_allocator; 230 231 // GC allocation statistics policy for survivors. 232 G1EvacStats _survivor_evac_stats; 233 234 // GC allocation statistics policy for tenured objects. 235 G1EvacStats _old_evac_stats; 236 237 // It specifies whether we should attempt to expand the heap after a 238 // region allocation failure. If heap expansion fails we set this to 239 // false so that we don't re-attempt the heap expansion (it's likely 240 // that subsequent expansion attempts will also fail if one fails). 241 // Currently, it is only consulted during GC and it's reset at the 242 // start of each GC. 243 bool _expand_heap_after_alloc_failure; 244 245 // Helper for monitoring and management support. 246 G1MonitoringSupport* _g1mm; 247 248 // Records whether the region at the given index is (still) a 249 // candidate for eager reclaim. Only valid for humongous start 250 // regions; other regions have unspecified values. Humongous start 251 // regions are initialized at start of collection pause, with 252 // candidates removed from the set as they are found reachable from 253 // roots or the young generation. 254 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 255 protected: 256 bool default_value() const { return false; } 257 public: 258 void clear() { G1BiasedMappedArray<bool>::clear(); } 259 void set_candidate(uint region, bool value) { 260 set_by_index(region, value); 261 } 262 bool is_candidate(uint region) { 263 return get_by_index(region); 264 } 265 }; 266 267 HumongousReclaimCandidates _humongous_reclaim_candidates; 268 // Stores whether during humongous object registration we found candidate regions. 269 // If not, we can skip a few steps. 270 bool _has_humongous_reclaim_candidates; 271 272 G1HRPrinter _hr_printer; 273 274 // It decides whether an explicit GC should start a concurrent cycle 275 // instead of doing a STW GC. Currently, a concurrent cycle is 276 // explicitly started if: 277 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 278 // (b) cause == _g1_humongous_allocation 279 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 280 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 281 // (e) cause == _wb_conc_mark 282 bool should_do_concurrent_full_gc(GCCause::Cause cause); 283 284 // indicates whether we are in young or mixed GC mode 285 G1CollectorState _collector_state; 286 287 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 288 // concurrent cycles) we have started. 289 volatile uint _old_marking_cycles_started; 290 291 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 292 // concurrent cycles) we have completed. 293 volatile uint _old_marking_cycles_completed; 294 295 // This is a non-product method that is helpful for testing. It is 296 // called at the end of a GC and artificially expands the heap by 297 // allocating a number of dead regions. This way we can induce very 298 // frequent marking cycles and stress the cleanup / concurrent 299 // cleanup code more (as all the regions that will be allocated by 300 // this method will be found dead by the marking cycle). 301 void allocate_dummy_regions() PRODUCT_RETURN; 302 303 // If the HR printer is active, dump the state of the regions in the 304 // heap after a compaction. 305 void print_hrm_post_compaction(); 306 307 // Create a memory mapper for auxiliary data structures of the given size and 308 // translation factor. 309 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 310 size_t size, 311 size_t translation_factor); 312 313 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 314 315 // These are macros so that, if the assert fires, we get the correct 316 // line number, file, etc. 317 318 #define heap_locking_asserts_params(_extra_message_) \ 319 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 320 (_extra_message_), \ 321 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 322 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 323 BOOL_TO_STR(Thread::current()->is_VM_thread()) 324 325 #define assert_heap_locked() \ 326 do { \ 327 assert(Heap_lock->owned_by_self(), \ 328 heap_locking_asserts_params("should be holding the Heap_lock")); \ 329 } while (0) 330 331 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 332 do { \ 333 assert(Heap_lock->owned_by_self() || \ 334 (SafepointSynchronize::is_at_safepoint() && \ 335 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 336 heap_locking_asserts_params("should be holding the Heap_lock or " \ 337 "should be at a safepoint")); \ 338 } while (0) 339 340 #define assert_heap_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 be holding the Heap_lock and " \ 345 "should not be at a safepoint")); \ 346 } while (0) 347 348 #define assert_heap_not_locked() \ 349 do { \ 350 assert(!Heap_lock->owned_by_self(), \ 351 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 352 } while (0) 353 354 #define assert_heap_not_locked_and_not_at_safepoint() \ 355 do { \ 356 assert(!Heap_lock->owned_by_self() && \ 357 !SafepointSynchronize::is_at_safepoint(), \ 358 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 359 "should not be at a safepoint")); \ 360 } while (0) 361 362 #define assert_at_safepoint_on_vm_thread() \ 363 do { \ 364 assert_at_safepoint(); \ 365 assert(Thread::current_or_null() != NULL, "no current thread"); \ 366 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \ 367 } while (0) 368 369 // The young region list. 370 G1EdenRegions _eden; 371 G1SurvivorRegions _survivor; 372 373 STWGCTimer* _gc_timer_stw; 374 375 G1NewTracer* _gc_tracer_stw; 376 377 // The current policy object for the collector. 378 G1Policy* _g1_policy; 379 G1HeapSizingPolicy* _heap_sizing_policy; 380 381 G1CollectionSet _collection_set; 382 383 // Try to allocate a single non-humongous HeapRegion sufficient for 384 // an allocation of the given word_size. If do_expand is true, 385 // attempt to expand the heap if necessary to satisfy the allocation 386 // request. If the region is to be used as an old region or for a 387 // humongous object, set is_old to true. If not, to false. 388 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 389 390 // Initialize a contiguous set of free regions of length num_regions 391 // and starting at index first so that they appear as a single 392 // humongous region. 393 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 394 uint num_regions, 395 size_t word_size); 396 397 // Attempt to allocate a humongous object of the given size. Return 398 // NULL if unsuccessful. 399 HeapWord* humongous_obj_allocate(size_t word_size); 400 401 // The following two methods, allocate_new_tlab() and 402 // mem_allocate(), are the two main entry points from the runtime 403 // into the G1's allocation routines. They have the following 404 // assumptions: 405 // 406 // * They should both be called outside safepoints. 407 // 408 // * They should both be called without holding the Heap_lock. 409 // 410 // * All allocation requests for new TLABs should go to 411 // allocate_new_tlab(). 412 // 413 // * All non-TLAB allocation requests should go to mem_allocate(). 414 // 415 // * If either call cannot satisfy the allocation request using the 416 // current allocating region, they will try to get a new one. If 417 // this fails, they will attempt to do an evacuation pause and 418 // retry the allocation. 419 // 420 // * If all allocation attempts fail, even after trying to schedule 421 // an evacuation pause, allocate_new_tlab() will return NULL, 422 // whereas mem_allocate() will attempt a heap expansion and/or 423 // schedule a Full GC. 424 // 425 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 426 // should never be called with word_size being humongous. All 427 // humongous allocation requests should go to mem_allocate() which 428 // will satisfy them with a special path. 429 430 virtual HeapWord* allocate_new_tlab(size_t word_size); 431 432 virtual HeapWord* mem_allocate(size_t word_size, 433 bool* gc_overhead_limit_was_exceeded); 434 435 // First-level mutator allocation attempt: try to allocate out of 436 // the mutator alloc region without taking the Heap_lock. This 437 // should only be used for non-humongous allocations. 438 inline HeapWord* attempt_allocation(size_t word_size); 439 440 // Second-level mutator allocation attempt: take the Heap_lock and 441 // retry the allocation attempt, potentially scheduling a GC 442 // pause. This should only be used for non-humongous allocations. 443 HeapWord* attempt_allocation_slow(size_t word_size); 444 445 // Takes the Heap_lock and attempts a humongous allocation. It can 446 // potentially schedule a GC pause. 447 HeapWord* attempt_allocation_humongous(size_t word_size); 448 449 // Allocation attempt that should be called during safepoints (e.g., 450 // at the end of a successful GC). expect_null_mutator_alloc_region 451 // specifies whether the mutator alloc region is expected to be NULL 452 // or not. 453 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 454 bool expect_null_mutator_alloc_region); 455 456 // These methods are the "callbacks" from the G1AllocRegion class. 457 458 // For mutator alloc regions. 459 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 460 void retire_mutator_alloc_region(HeapRegion* alloc_region, 461 size_t allocated_bytes); 462 463 // For GC alloc regions. 464 bool has_more_regions(InCSetState dest); 465 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest); 466 void retire_gc_alloc_region(HeapRegion* alloc_region, 467 size_t allocated_bytes, InCSetState dest); 468 469 // - if explicit_gc is true, the GC is for a System.gc() etc, 470 // otherwise it's for a failed allocation. 471 // - if clear_all_soft_refs is true, all soft references should be 472 // cleared during the GC. 473 // - it returns false if it is unable to do the collection due to the 474 // GC locker being active, true otherwise. 475 bool do_full_collection(bool explicit_gc, 476 bool clear_all_soft_refs); 477 478 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 479 virtual void do_full_collection(bool clear_all_soft_refs); 480 481 // Resize the heap if necessary after a full collection. 482 void resize_if_necessary_after_full_collection(); 483 484 // Callback from VM_G1CollectForAllocation operation. 485 // This function does everything necessary/possible to satisfy a 486 // failed allocation request (including collection, expansion, etc.) 487 HeapWord* satisfy_failed_allocation(size_t word_size, 488 bool* succeeded); 489 // Internal helpers used during full GC to split it up to 490 // increase readability. 491 void abort_concurrent_cycle(); 492 void verify_before_full_collection(bool explicit_gc); 493 void prepare_heap_for_full_collection(); 494 void prepare_heap_for_mutators(); 495 void abort_refinement(); 496 void verify_after_full_collection(); 497 void print_heap_after_full_collection(G1HeapTransition* heap_transition); 498 499 // Helper method for satisfy_failed_allocation() 500 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 501 bool do_gc, 502 bool clear_all_soft_refs, 503 bool expect_null_mutator_alloc_region, 504 bool* gc_succeeded); 505 506 // Attempting to expand the heap sufficiently 507 // to support an allocation of the given "word_size". If 508 // successful, perform the allocation and return the address of the 509 // allocated block, or else "NULL". 510 HeapWord* expand_and_allocate(size_t word_size); 511 512 // Process any reference objects discovered. 513 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 514 515 // If during an initial mark pause we install a pending list head which is not otherwise reachable 516 // ensure that it is marked in the bitmap for concurrent marking to discover. 517 void make_pending_list_reachable(); 518 519 // Merges the information gathered on a per-thread basis for all worker threads 520 // during GC into global variables. 521 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states); 522 public: 523 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; } 524 525 WorkGang* workers() const { return _workers; } 526 527 G1Allocator* allocator() { 528 return _allocator; 529 } 530 531 G1HeapVerifier* verifier() { 532 return _verifier; 533 } 534 535 G1MonitoringSupport* g1mm() { 536 assert(_g1mm != NULL, "should have been initialized"); 537 return _g1mm; 538 } 539 540 // Expand the garbage-first heap by at least the given size (in bytes!). 541 // Returns true if the heap was expanded by the requested amount; 542 // false otherwise. 543 // (Rounds up to a HeapRegion boundary.) 544 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL); 545 546 // Returns the PLAB statistics for a given destination. 547 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 548 549 // Determines PLAB size for a given destination. 550 inline size_t desired_plab_sz(InCSetState dest); 551 552 // Do anything common to GC's. 553 void gc_prologue(bool full); 554 void gc_epilogue(bool full); 555 556 // Does the given region fulfill remembered set based eager reclaim candidate requirements? 557 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const; 558 559 // Modify the reclaim candidate set and test for presence. 560 // These are only valid for starts_humongous regions. 561 inline void set_humongous_reclaim_candidate(uint region, bool value); 562 inline bool is_humongous_reclaim_candidate(uint region); 563 564 // Remove from the reclaim candidate set. Also remove from the 565 // collection set so that later encounters avoid the slow path. 566 inline void set_humongous_is_live(oop obj); 567 568 // Register the given region to be part of the collection set. 569 inline void register_humongous_region_with_cset(uint index); 570 // Register regions with humongous objects (actually on the start region) in 571 // the in_cset_fast_test table. 572 void register_humongous_regions_with_cset(); 573 // We register a region with the fast "in collection set" test. We 574 // simply set to true the array slot corresponding to this region. 575 void register_young_region_with_cset(HeapRegion* r) { 576 _in_cset_fast_test.set_in_young(r->hrm_index()); 577 } 578 void register_old_region_with_cset(HeapRegion* r) { 579 _in_cset_fast_test.set_in_old(r->hrm_index()); 580 } 581 void clear_in_cset(const HeapRegion* hr) { 582 _in_cset_fast_test.clear(hr); 583 } 584 585 void clear_cset_fast_test() { 586 _in_cset_fast_test.clear(); 587 } 588 589 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 590 591 // This is called at the start of either a concurrent cycle or a Full 592 // GC to update the number of old marking cycles started. 593 void increment_old_marking_cycles_started(); 594 595 // This is called at the end of either a concurrent cycle or a Full 596 // GC to update the number of old marking cycles completed. Those two 597 // can happen in a nested fashion, i.e., we start a concurrent 598 // cycle, a Full GC happens half-way through it which ends first, 599 // and then the cycle notices that a Full GC happened and ends 600 // too. The concurrent parameter is a boolean to help us do a bit 601 // tighter consistency checking in the method. If concurrent is 602 // false, the caller is the inner caller in the nesting (i.e., the 603 // Full GC). If concurrent is true, the caller is the outer caller 604 // in this nesting (i.e., the concurrent cycle). Further nesting is 605 // not currently supported. The end of this call also notifies 606 // the FullGCCount_lock in case a Java thread is waiting for a full 607 // GC to happen (e.g., it called System.gc() with 608 // +ExplicitGCInvokesConcurrent). 609 void increment_old_marking_cycles_completed(bool concurrent); 610 611 uint old_marking_cycles_completed() { 612 return _old_marking_cycles_completed; 613 } 614 615 G1HRPrinter* hr_printer() { return &_hr_printer; } 616 617 // Allocates a new heap region instance. 618 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 619 620 // Allocate the highest free region in the reserved heap. This will commit 621 // regions as necessary. 622 HeapRegion* alloc_highest_free_region(); 623 624 // Frees a non-humongous region by initializing its contents and 625 // adding it to the free list that's passed as a parameter (this is 626 // usually a local list which will be appended to the master free 627 // list later). The used bytes of freed regions are accumulated in 628 // pre_used. If skip_remset is true, the region's RSet will not be freed 629 // up. If skip_hot_card_cache is true, the region's hot card cache will not 630 // be freed up. The assumption is that this will be done later. 631 // The locked parameter indicates if the caller has already taken 632 // care of proper synchronization. This may allow some optimizations. 633 void free_region(HeapRegion* hr, 634 FreeRegionList* free_list, 635 bool skip_remset, 636 bool skip_hot_card_cache = false, 637 bool locked = false); 638 639 // It dirties the cards that cover the block so that the post 640 // write barrier never queues anything when updating objects on this 641 // block. It is assumed (and in fact we assert) that the block 642 // belongs to a young region. 643 inline void dirty_young_block(HeapWord* start, size_t word_size); 644 645 // Frees a humongous region by collapsing it into individual regions 646 // and calling free_region() for each of them. The freed regions 647 // will be added to the free list that's passed as a parameter (this 648 // is usually a local list which will be appended to the master free 649 // list later). 650 // The method assumes that only a single thread is ever calling 651 // this for a particular region at once. 652 void free_humongous_region(HeapRegion* hr, 653 FreeRegionList* free_list); 654 655 // Facility for allocating in 'archive' regions in high heap memory and 656 // recording the allocated ranges. These should all be called from the 657 // VM thread at safepoints, without the heap lock held. They can be used 658 // to create and archive a set of heap regions which can be mapped at the 659 // same fixed addresses in a subsequent JVM invocation. 660 void begin_archive_alloc_range(bool open = false); 661 662 // Check if the requested size would be too large for an archive allocation. 663 bool is_archive_alloc_too_large(size_t word_size); 664 665 // Allocate memory of the requested size from the archive region. This will 666 // return NULL if the size is too large or if no memory is available. It 667 // does not trigger a garbage collection. 668 HeapWord* archive_mem_allocate(size_t word_size); 669 670 // Optionally aligns the end address and returns the allocated ranges in 671 // an array of MemRegions in order of ascending addresses. 672 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 673 size_t end_alignment_in_bytes = 0); 674 675 // Facility for allocating a fixed range within the heap and marking 676 // the containing regions as 'archive'. For use at JVM init time, when the 677 // caller may mmap archived heap data at the specified range(s). 678 // Verify that the MemRegions specified in the argument array are within the 679 // reserved heap. 680 bool check_archive_addresses(MemRegion* range, size_t count); 681 682 // Commit the appropriate G1 regions containing the specified MemRegions 683 // and mark them as 'archive' regions. The regions in the array must be 684 // non-overlapping and in order of ascending address. 685 bool alloc_archive_regions(MemRegion* range, size_t count, bool open); 686 687 // Insert any required filler objects in the G1 regions around the specified 688 // ranges to make the regions parseable. This must be called after 689 // alloc_archive_regions, and after class loading has occurred. 690 void fill_archive_regions(MemRegion* range, size_t count); 691 692 // For each of the specified MemRegions, uncommit the containing G1 regions 693 // which had been allocated by alloc_archive_regions. This should be called 694 // rather than fill_archive_regions at JVM init time if the archive file 695 // mapping failed, with the same non-overlapping and sorted MemRegion array. 696 void dealloc_archive_regions(MemRegion* range, size_t count); 697 698 private: 699 700 // Shrink the garbage-first heap by at most the given size (in bytes!). 701 // (Rounds down to a HeapRegion boundary.) 702 void shrink(size_t expand_bytes); 703 void shrink_helper(size_t expand_bytes); 704 705 #if TASKQUEUE_STATS 706 static void print_taskqueue_stats_hdr(outputStream* const st); 707 void print_taskqueue_stats() const; 708 void reset_taskqueue_stats(); 709 #endif // TASKQUEUE_STATS 710 711 // Schedule the VM operation that will do an evacuation pause to 712 // satisfy an allocation request of word_size. *succeeded will 713 // return whether the VM operation was successful (it did do an 714 // evacuation pause) or not (another thread beat us to it or the GC 715 // locker was active). Given that we should not be holding the 716 // Heap_lock when we enter this method, we will pass the 717 // gc_count_before (i.e., total_collections()) as a parameter since 718 // it has to be read while holding the Heap_lock. Currently, both 719 // methods that call do_collection_pause() release the Heap_lock 720 // before the call, so it's easy to read gc_count_before just before. 721 HeapWord* do_collection_pause(size_t word_size, 722 uint gc_count_before, 723 bool* succeeded, 724 GCCause::Cause gc_cause); 725 726 void wait_for_root_region_scanning(); 727 728 // The guts of the incremental collection pause, executed by the vm 729 // thread. It returns false if it is unable to do the collection due 730 // to the GC locker being active, true otherwise 731 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 732 733 // Actually do the work of evacuating the collection set. 734 void evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states); 735 736 void pre_evacuate_collection_set(); 737 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 738 739 // Print the header for the per-thread termination statistics. 740 static void print_termination_stats_hdr(); 741 // Print actual per-thread termination statistics. 742 void print_termination_stats(uint worker_id, 743 double elapsed_ms, 744 double strong_roots_ms, 745 double term_ms, 746 size_t term_attempts, 747 size_t alloc_buffer_waste, 748 size_t undo_waste) const; 749 // Update object copying statistics. 750 void record_obj_copy_mem_stats(); 751 752 // The hot card cache for remembered set insertion optimization. 753 G1HotCardCache* _hot_card_cache; 754 755 // The g1 remembered set of the heap. 756 G1RemSet* _g1_rem_set; 757 758 // A set of cards that cover the objects for which the Rsets should be updated 759 // concurrently after the collection. 760 DirtyCardQueueSet _dirty_card_queue_set; 761 762 // After a collection pause, convert the regions in the collection set into free 763 // regions. 764 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 765 766 // Abandon the current collection set without recording policy 767 // statistics or updating free lists. 768 void abandon_collection_set(G1CollectionSet* collection_set); 769 770 // The concurrent marker (and the thread it runs in.) 771 G1ConcurrentMark* _cm; 772 G1ConcurrentMarkThread* _cm_thread; 773 774 // The concurrent refiner. 775 G1ConcurrentRefine* _cr; 776 777 // The parallel task queues 778 RefToScanQueueSet *_task_queues; 779 780 // True iff a evacuation has failed in the current collection. 781 bool _evacuation_failed; 782 783 EvacuationFailedInfo* _evacuation_failed_info_array; 784 785 // Failed evacuations cause some logical from-space objects to have 786 // forwarding pointers to themselves. Reset them. 787 void remove_self_forwarding_pointers(); 788 789 // Restore the objects in the regions in the collection set after an 790 // evacuation failure. 791 void restore_after_evac_failure(); 792 793 PreservedMarksSet _preserved_marks_set; 794 795 // Preserve the mark of "obj", if necessary, in preparation for its mark 796 // word being overwritten with a self-forwarding-pointer. 797 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 798 799 #ifndef PRODUCT 800 // Support for forcing evacuation failures. Analogous to 801 // PromotionFailureALot for the other collectors. 802 803 // Records whether G1EvacuationFailureALot should be in effect 804 // for the current GC 805 bool _evacuation_failure_alot_for_current_gc; 806 807 // Used to record the GC number for interval checking when 808 // determining whether G1EvaucationFailureALot is in effect 809 // for the current GC. 810 size_t _evacuation_failure_alot_gc_number; 811 812 // Count of the number of evacuations between failures. 813 volatile size_t _evacuation_failure_alot_count; 814 815 // Set whether G1EvacuationFailureALot should be in effect 816 // for the current GC (based upon the type of GC and which 817 // command line flags are set); 818 inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc, 819 bool during_initial_mark, 820 bool mark_or_rebuild_in_progress); 821 822 inline void set_evacuation_failure_alot_for_current_gc(); 823 824 // Return true if it's time to cause an evacuation failure. 825 inline bool evacuation_should_fail(); 826 827 // Reset the G1EvacuationFailureALot counters. Should be called at 828 // the end of an evacuation pause in which an evacuation failure occurred. 829 inline void reset_evacuation_should_fail(); 830 #endif // !PRODUCT 831 832 // ("Weak") Reference processing support. 833 // 834 // G1 has 2 instances of the reference processor class. One 835 // (_ref_processor_cm) handles reference object discovery 836 // and subsequent processing during concurrent marking cycles. 837 // 838 // The other (_ref_processor_stw) handles reference object 839 // discovery and processing during full GCs and incremental 840 // evacuation pauses. 841 // 842 // During an incremental pause, reference discovery will be 843 // temporarily disabled for _ref_processor_cm and will be 844 // enabled for _ref_processor_stw. At the end of the evacuation 845 // pause references discovered by _ref_processor_stw will be 846 // processed and discovery will be disabled. The previous 847 // setting for reference object discovery for _ref_processor_cm 848 // will be re-instated. 849 // 850 // At the start of marking: 851 // * Discovery by the CM ref processor is verified to be inactive 852 // and it's discovered lists are empty. 853 // * Discovery by the CM ref processor is then enabled. 854 // 855 // At the end of marking: 856 // * Any references on the CM ref processor's discovered 857 // lists are processed (possibly MT). 858 // 859 // At the start of full GC we: 860 // * Disable discovery by the CM ref processor and 861 // empty CM ref processor's discovered lists 862 // (without processing any entries). 863 // * Verify that the STW ref processor is inactive and it's 864 // discovered lists are empty. 865 // * Temporarily set STW ref processor discovery as single threaded. 866 // * Temporarily clear the STW ref processor's _is_alive_non_header 867 // field. 868 // * Finally enable discovery by the STW ref processor. 869 // 870 // The STW ref processor is used to record any discovered 871 // references during the full GC. 872 // 873 // At the end of a full GC we: 874 // * Enqueue any reference objects discovered by the STW ref processor 875 // that have non-live referents. This has the side-effect of 876 // making the STW ref processor inactive by disabling discovery. 877 // * Verify that the CM ref processor is still inactive 878 // and no references have been placed on it's discovered 879 // lists (also checked as a precondition during initial marking). 880 881 // The (stw) reference processor... 882 ReferenceProcessor* _ref_processor_stw; 883 884 // During reference object discovery, the _is_alive_non_header 885 // closure (if non-null) is applied to the referent object to 886 // determine whether the referent is live. If so then the 887 // reference object does not need to be 'discovered' and can 888 // be treated as a regular oop. This has the benefit of reducing 889 // the number of 'discovered' reference objects that need to 890 // be processed. 891 // 892 // Instance of the is_alive closure for embedding into the 893 // STW reference processor as the _is_alive_non_header field. 894 // Supplying a value for the _is_alive_non_header field is 895 // optional but doing so prevents unnecessary additions to 896 // the discovered lists during reference discovery. 897 G1STWIsAliveClosure _is_alive_closure_stw; 898 899 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw; 900 901 // The (concurrent marking) reference processor... 902 ReferenceProcessor* _ref_processor_cm; 903 904 // Instance of the concurrent mark is_alive closure for embedding 905 // into the Concurrent Marking reference processor as the 906 // _is_alive_non_header field. Supplying a value for the 907 // _is_alive_non_header field is optional but doing so prevents 908 // unnecessary additions to the discovered lists during reference 909 // discovery. 910 G1CMIsAliveClosure _is_alive_closure_cm; 911 912 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm; 913 public: 914 915 RefToScanQueue *task_queue(uint i) const; 916 917 uint num_task_queues() const; 918 919 // A set of cards where updates happened during the GC 920 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 921 922 // Create a G1CollectedHeap with the specified policy. 923 // Must call the initialize method afterwards. 924 // May not return if something goes wrong. 925 G1CollectedHeap(G1CollectorPolicy* policy); 926 927 private: 928 jint initialize_concurrent_refinement(); 929 jint initialize_young_gen_sampling_thread(); 930 public: 931 // Initialize the G1CollectedHeap to have the initial and 932 // maximum sizes and remembered and barrier sets 933 // specified by the policy object. 934 jint initialize(); 935 936 virtual void stop(); 937 virtual void safepoint_synchronize_begin(); 938 virtual void safepoint_synchronize_end(); 939 940 // Return the (conservative) maximum heap alignment for any G1 heap 941 static size_t conservative_max_heap_alignment(); 942 943 // Does operations required after initialization has been done. 944 void post_initialize(); 945 946 // Initialize weak reference processing. 947 void ref_processing_init(); 948 949 virtual Name kind() const { 950 return CollectedHeap::G1; 951 } 952 953 virtual const char* name() const { 954 return "G1"; 955 } 956 957 const G1CollectorState* collector_state() const { return &_collector_state; } 958 G1CollectorState* collector_state() { return &_collector_state; } 959 960 // The current policy object for the collector. 961 G1Policy* g1_policy() const { return _g1_policy; } 962 963 const G1CollectionSet* collection_set() const { return &_collection_set; } 964 G1CollectionSet* collection_set() { return &_collection_set; } 965 966 virtual CollectorPolicy* collector_policy() const; 967 968 virtual SoftRefPolicy* soft_ref_policy(); 969 970 virtual GrowableArray<GCMemoryManager*> memory_managers(); 971 virtual GrowableArray<MemoryPool*> memory_pools(); 972 973 // The rem set and barrier set. 974 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 975 976 // Try to minimize the remembered set. 977 void scrub_rem_set(); 978 979 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 980 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i); 981 982 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. 983 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i); 984 985 // The shared block offset table array. 986 G1BlockOffsetTable* bot() const { return _bot; } 987 988 // Reference Processing accessors 989 990 // The STW reference processor.... 991 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 992 993 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 994 995 // The Concurrent Marking reference processor... 996 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 997 998 size_t unused_committed_regions_in_bytes() const; 999 virtual size_t capacity() const; 1000 virtual size_t used() const; 1001 // This should be called when we're not holding the heap lock. The 1002 // result might be a bit inaccurate. 1003 size_t used_unlocked() const; 1004 size_t recalculate_used() const; 1005 1006 // These virtual functions do the actual allocation. 1007 // Some heaps may offer a contiguous region for shared non-blocking 1008 // allocation, via inlined code (by exporting the address of the top and 1009 // end fields defining the extent of the contiguous allocation region.) 1010 // But G1CollectedHeap doesn't yet support this. 1011 1012 virtual bool is_maximal_no_gc() const { 1013 return _hrm.available() == 0; 1014 } 1015 1016 // Returns whether there are any regions left in the heap for allocation. 1017 bool has_regions_left_for_allocation() const { 1018 return !is_maximal_no_gc() || num_free_regions() != 0; 1019 } 1020 1021 // The current number of regions in the heap. 1022 uint num_regions() const { return _hrm.length(); } 1023 1024 // The max number of regions in the heap. 1025 uint max_regions() const { return _hrm.max_length(); } 1026 1027 // The number of regions that are completely free. 1028 uint num_free_regions() const { return _hrm.num_free_regions(); } 1029 1030 MemoryUsage get_auxiliary_data_memory_usage() const { 1031 return _hrm.get_auxiliary_data_memory_usage(); 1032 } 1033 1034 // The number of regions that are not completely free. 1035 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1036 1037 #ifdef ASSERT 1038 bool is_on_master_free_list(HeapRegion* hr) { 1039 return _hrm.is_free(hr); 1040 } 1041 #endif // ASSERT 1042 1043 inline void old_set_add(HeapRegion* hr); 1044 inline void old_set_remove(HeapRegion* hr); 1045 1046 size_t non_young_capacity_bytes() { 1047 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes; 1048 } 1049 1050 // Determine whether the given region is one that we are using as an 1051 // old GC alloc region. 1052 bool is_old_gc_alloc_region(HeapRegion* hr); 1053 1054 // Perform a collection of the heap; intended for use in implementing 1055 // "System.gc". This probably implies as full a collection as the 1056 // "CollectedHeap" supports. 1057 virtual void collect(GCCause::Cause cause); 1058 1059 // True iff an evacuation has failed in the most-recent collection. 1060 bool evacuation_failed() { return _evacuation_failed; } 1061 1062 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed); 1063 void prepend_to_freelist(FreeRegionList* list); 1064 void decrement_summary_bytes(size_t bytes); 1065 1066 virtual bool is_in(const void* p) const; 1067 #ifdef ASSERT 1068 // Returns whether p is in one of the available areas of the heap. Slow but 1069 // extensive version. 1070 bool is_in_exact(const void* p) const; 1071 #endif 1072 1073 // Return "TRUE" iff the given object address is within the collection 1074 // set. Assumes that the reference points into the heap. 1075 inline bool is_in_cset(const HeapRegion *hr); 1076 inline bool is_in_cset(oop obj); 1077 inline bool is_in_cset(HeapWord* addr); 1078 1079 inline bool is_in_cset_or_humongous(const oop obj); 1080 1081 private: 1082 // This array is used for a quick test on whether a reference points into 1083 // the collection set or not. Each of the array's elements denotes whether the 1084 // corresponding region is in the collection set or not. 1085 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1086 1087 public: 1088 1089 inline InCSetState in_cset_state(const oop obj); 1090 1091 // Return "TRUE" iff the given object address is in the reserved 1092 // region of g1. 1093 bool is_in_g1_reserved(const void* p) const { 1094 return _hrm.reserved().contains(p); 1095 } 1096 1097 // Returns a MemRegion that corresponds to the space that has been 1098 // reserved for the heap 1099 MemRegion g1_reserved() const { 1100 return _hrm.reserved(); 1101 } 1102 1103 virtual bool is_in_closed_subset(const void* p) const; 1104 1105 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; } 1106 1107 G1CardTable* card_table() const { 1108 return _card_table; 1109 } 1110 1111 // Iteration functions. 1112 1113 // Iterate over all objects, calling "cl.do_object" on each. 1114 virtual void object_iterate(ObjectClosure* cl); 1115 1116 virtual void safe_object_iterate(ObjectClosure* cl) { 1117 object_iterate(cl); 1118 } 1119 1120 // Iterate over heap regions, in address order, terminating the 1121 // iteration early if the "do_heap_region" method returns "true". 1122 void heap_region_iterate(HeapRegionClosure* blk) const; 1123 1124 // Return the region with the given index. It assumes the index is valid. 1125 inline HeapRegion* region_at(uint index) const; 1126 1127 // Return the next region (by index) that is part of the same 1128 // humongous object that hr is part of. 1129 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1130 1131 // Calculate the region index of the given address. Given address must be 1132 // within the heap. 1133 inline uint addr_to_region(HeapWord* addr) const; 1134 1135 inline HeapWord* bottom_addr_for_region(uint index) const; 1136 1137 // Two functions to iterate over the heap regions in parallel. Threads 1138 // compete using the HeapRegionClaimer to claim the regions before 1139 // applying the closure on them. 1140 // The _from_worker_offset version uses the HeapRegionClaimer and 1141 // the worker id to calculate a start offset to prevent all workers to 1142 // start from the point. 1143 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 1144 HeapRegionClaimer* hrclaimer, 1145 uint worker_id) const; 1146 1147 void heap_region_par_iterate_from_start(HeapRegionClosure* cl, 1148 HeapRegionClaimer* hrclaimer) const; 1149 1150 // Iterate over the regions (if any) in the current collection set. 1151 void collection_set_iterate(HeapRegionClosure* blk); 1152 1153 // Iterate over the regions (if any) in the current collection set. Starts the 1154 // iteration over the entire collection set so that the start regions of a given 1155 // worker id over the set active_workers are evenly spread across the set of 1156 // collection set regions. 1157 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id); 1158 1159 // Returns the HeapRegion that contains addr. addr must not be NULL. 1160 template <class T> 1161 inline HeapRegion* heap_region_containing(const T addr) const; 1162 1163 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1164 // each address in the (reserved) heap is a member of exactly 1165 // one block. The defining characteristic of a block is that it is 1166 // possible to find its size, and thus to progress forward to the next 1167 // block. (Blocks may be of different sizes.) Thus, blocks may 1168 // represent Java objects, or they might be free blocks in a 1169 // free-list-based heap (or subheap), as long as the two kinds are 1170 // distinguishable and the size of each is determinable. 1171 1172 // Returns the address of the start of the "block" that contains the 1173 // address "addr". We say "blocks" instead of "object" since some heaps 1174 // may not pack objects densely; a chunk may either be an object or a 1175 // non-object. 1176 virtual HeapWord* block_start(const void* addr) const; 1177 1178 // Requires "addr" to be the start of a chunk, and returns its size. 1179 // "addr + size" is required to be the start of a new chunk, or the end 1180 // of the active area of the heap. 1181 virtual size_t block_size(const HeapWord* addr) const; 1182 1183 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1184 // the block is an object. 1185 virtual bool block_is_obj(const HeapWord* addr) const; 1186 1187 // Section on thread-local allocation buffers (TLABs) 1188 // See CollectedHeap for semantics. 1189 1190 bool supports_tlab_allocation() const; 1191 size_t tlab_capacity(Thread* ignored) const; 1192 size_t tlab_used(Thread* ignored) const; 1193 size_t max_tlab_size() const; 1194 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1195 1196 inline bool is_in_young(const oop obj); 1197 1198 // Returns "true" iff the given word_size is "very large". 1199 static bool is_humongous(size_t word_size) { 1200 // Note this has to be strictly greater-than as the TLABs 1201 // are capped at the humongous threshold and we want to 1202 // ensure that we don't try to allocate a TLAB as 1203 // humongous and that we don't allocate a humongous 1204 // object in a TLAB. 1205 return word_size > _humongous_object_threshold_in_words; 1206 } 1207 1208 // Returns the humongous threshold for a specific region size 1209 static size_t humongous_threshold_for(size_t region_size) { 1210 return (region_size / 2); 1211 } 1212 1213 // Returns the number of regions the humongous object of the given word size 1214 // requires. 1215 static size_t humongous_obj_size_in_regions(size_t word_size); 1216 1217 // Print the maximum heap capacity. 1218 virtual size_t max_capacity() const; 1219 1220 virtual jlong millis_since_last_gc(); 1221 1222 1223 // Convenience function to be used in situations where the heap type can be 1224 // asserted to be this type. 1225 static G1CollectedHeap* heap(); 1226 1227 void set_region_short_lived_locked(HeapRegion* hr); 1228 // add appropriate methods for any other surv rate groups 1229 1230 const G1SurvivorRegions* survivor() const { return &_survivor; } 1231 1232 uint survivor_regions_count() const { 1233 return _survivor.length(); 1234 } 1235 1236 uint eden_regions_count() const { 1237 return _eden.length(); 1238 } 1239 1240 uint young_regions_count() const { 1241 return _eden.length() + _survivor.length(); 1242 } 1243 1244 uint old_regions_count() const { return _old_set.length(); } 1245 1246 uint humongous_regions_count() const { return _humongous_set.length(); } 1247 1248 #ifdef ASSERT 1249 bool check_young_list_empty(); 1250 #endif 1251 1252 // *** Stuff related to concurrent marking. It's not clear to me that so 1253 // many of these need to be public. 1254 1255 // The functions below are helper functions that a subclass of 1256 // "CollectedHeap" can use in the implementation of its virtual 1257 // functions. 1258 // This performs a concurrent marking of the live objects in a 1259 // bitmap off to the side. 1260 void do_concurrent_mark(); 1261 1262 bool is_marked_next(oop obj) const; 1263 1264 // Determine if an object is dead, given the object and also 1265 // the region to which the object belongs. An object is dead 1266 // iff a) it was not allocated since the last mark, b) it 1267 // is not marked, and c) it is not in an archive region. 1268 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1269 return 1270 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) && 1271 !hr->is_archive(); 1272 } 1273 1274 // This function returns true when an object has been 1275 // around since the previous marking and hasn't yet 1276 // been marked during this marking, and is not in an archive region. 1277 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1278 return 1279 !hr->obj_allocated_since_next_marking(obj) && 1280 !is_marked_next(obj) && 1281 !hr->is_archive(); 1282 } 1283 1284 // Determine if an object is dead, given only the object itself. 1285 // This will find the region to which the object belongs and 1286 // then call the region version of the same function. 1287 1288 // Added if it is NULL it isn't dead. 1289 1290 inline bool is_obj_dead(const oop obj) const; 1291 1292 inline bool is_obj_ill(const oop obj) const; 1293 1294 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const; 1295 inline bool is_obj_dead_full(const oop obj) const; 1296 1297 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1298 1299 // Refinement 1300 1301 G1ConcurrentRefine* concurrent_refine() const { return _cr; } 1302 1303 // Optimized nmethod scanning support routines 1304 1305 // Is an oop scavengeable 1306 virtual bool is_scavengable(oop obj); 1307 1308 // Register the given nmethod with the G1 heap. 1309 virtual void register_nmethod(nmethod* nm); 1310 1311 // Unregister the given nmethod from the G1 heap. 1312 virtual void unregister_nmethod(nmethod* nm); 1313 1314 // Free up superfluous code root memory. 1315 void purge_code_root_memory(); 1316 1317 // Rebuild the strong code root lists for each region 1318 // after a full GC. 1319 void rebuild_strong_code_roots(); 1320 1321 // Partial cleaning used when class unloading is disabled. 1322 // Let the caller choose what structures to clean out: 1323 // - StringTable 1324 // - SymbolTable 1325 // - StringDeduplication structures 1326 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup); 1327 1328 // Complete cleaning used when class unloading is enabled. 1329 // Cleans out all structures handled by partial_cleaning and also the CodeCache. 1330 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); 1331 1332 // Redirty logged cards in the refinement queue. 1333 void redirty_logged_cards(); 1334 // Verification 1335 1336 // Perform any cleanup actions necessary before allowing a verification. 1337 virtual void prepare_for_verify(); 1338 1339 // Perform verification. 1340 1341 // vo == UsePrevMarking -> use "prev" marking information, 1342 // vo == UseNextMarking -> use "next" marking information 1343 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS 1344 // 1345 // NOTE: Only the "prev" marking information is guaranteed to be 1346 // consistent most of the time, so most calls to this should use 1347 // vo == UsePrevMarking. 1348 // Currently, there is only one case where this is called with 1349 // vo == UseNextMarking, which is to verify the "next" marking 1350 // information at the end of remark. 1351 // Currently there is only one place where this is called with 1352 // vo == UseFullMarking, which is to verify the marking during a 1353 // full GC. 1354 void verify(VerifyOption vo); 1355 1356 // WhiteBox testing support. 1357 virtual bool supports_concurrent_phase_control() const; 1358 virtual const char* const* concurrent_phases() const; 1359 virtual bool request_concurrent_phase(const char* phase); 1360 1361 // The methods below are here for convenience and dispatch the 1362 // appropriate method depending on value of the given VerifyOption 1363 // parameter. The values for that parameter, and their meanings, 1364 // are the same as those above. 1365 1366 bool is_obj_dead_cond(const oop obj, 1367 const HeapRegion* hr, 1368 const VerifyOption vo) const; 1369 1370 bool is_obj_dead_cond(const oop obj, 1371 const VerifyOption vo) const; 1372 1373 G1HeapSummary create_g1_heap_summary(); 1374 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1375 1376 // Printing 1377 private: 1378 void print_heap_regions() const; 1379 void print_regions_on(outputStream* st) const; 1380 1381 public: 1382 virtual void print_on(outputStream* st) const; 1383 virtual void print_extended_on(outputStream* st) const; 1384 virtual void print_on_error(outputStream* st) const; 1385 1386 virtual void print_gc_threads_on(outputStream* st) const; 1387 virtual void gc_threads_do(ThreadClosure* tc) const; 1388 1389 // Override 1390 void print_tracing_info() const; 1391 1392 // The following two methods are helpful for debugging RSet issues. 1393 void print_cset_rsets() PRODUCT_RETURN; 1394 void print_all_rsets() PRODUCT_RETURN; 1395 1396 public: 1397 size_t pending_card_num(); 1398 1399 private: 1400 size_t _max_heap_capacity; 1401 }; 1402 1403 class G1ParEvacuateFollowersClosure : public VoidClosure { 1404 private: 1405 double _start_term; 1406 double _term_time; 1407 size_t _term_attempts; 1408 1409 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 1410 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 1411 protected: 1412 G1CollectedHeap* _g1h; 1413 G1ParScanThreadState* _par_scan_state; 1414 RefToScanQueueSet* _queues; 1415 ParallelTaskTerminator* _terminator; 1416 1417 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 1418 RefToScanQueueSet* queues() { return _queues; } 1419 ParallelTaskTerminator* terminator() { return _terminator; } 1420 1421 public: 1422 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 1423 G1ParScanThreadState* par_scan_state, 1424 RefToScanQueueSet* queues, 1425 ParallelTaskTerminator* terminator) 1426 : _g1h(g1h), _par_scan_state(par_scan_state), 1427 _queues(queues), _terminator(terminator), 1428 _start_term(0.0), _term_time(0.0), _term_attempts(0) {} 1429 1430 void do_void(); 1431 1432 double term_time() const { return _term_time; } 1433 size_t term_attempts() const { return _term_attempts; } 1434 1435 private: 1436 inline bool offer_termination(); 1437 }; 1438 1439 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP