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 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 GCMemoryManager _memory_manager; 164 GCMemoryManager _full_gc_memory_manager; 165 166 MemoryPool* _eden_pool; 167 MemoryPool* _survivor_pool; 168 MemoryPool* _old_pool; 169 170 static size_t _humongous_object_threshold_in_words; 171 172 // It keeps track of the old regions. 173 HeapRegionSet _old_set; 174 175 // It keeps track of the humongous regions. 176 HeapRegionSet _humongous_set; 177 178 virtual void initialize_serviceability(); 179 180 void eagerly_reclaim_humongous_regions(); 181 // Start a new incremental collection set for the next pause. 182 void start_new_collection_set(); 183 184 // The number of regions we could create by expansion. 185 uint _expansion_regions; 186 187 // The block offset table for the G1 heap. 188 G1BlockOffsetTable* _bot; 189 190 // Tears down the region sets / lists so that they are empty and the 191 // regions on the heap do not belong to a region set / list. The 192 // only exception is the humongous set which we leave unaltered. If 193 // free_list_only is true, it will only tear down the master free 194 // list. It is called before a Full GC (free_list_only == false) or 195 // before heap shrinking (free_list_only == true). 196 void tear_down_region_sets(bool free_list_only); 197 198 // Rebuilds the region sets / lists so that they are repopulated to 199 // reflect the contents of the heap. The only exception is the 200 // humongous set which was not torn down in the first place. If 201 // free_list_only is true, it will only rebuild the master free 202 // list. It is called after a Full GC (free_list_only == false) or 203 // after heap shrinking (free_list_only == true). 204 void rebuild_region_sets(bool free_list_only); 205 206 // Callback for region mapping changed events. 207 G1RegionMappingChangedListener _listener; 208 209 // The sequence of all heap regions in the heap. 210 HeapRegionManager _hrm; 211 212 // Manages all allocations with regions except humongous object allocations. 213 G1Allocator* _allocator; 214 215 // Manages all heap verification. 216 G1HeapVerifier* _verifier; 217 218 // Outside of GC pauses, the number of bytes used in all regions other 219 // than the current allocation region(s). 220 size_t _summary_bytes_used; 221 222 void increase_used(size_t bytes); 223 void decrease_used(size_t bytes); 224 225 void set_used(size_t bytes); 226 227 // Class that handles archive allocation ranges. 228 G1ArchiveAllocator* _archive_allocator; 229 230 // GC allocation statistics policy for survivors. 231 G1EvacStats _survivor_evac_stats; 232 233 // GC allocation statistics policy for tenured objects. 234 G1EvacStats _old_evac_stats; 235 236 // It specifies whether we should attempt to expand the heap after a 237 // region allocation failure. If heap expansion fails we set this to 238 // false so that we don't re-attempt the heap expansion (it's likely 239 // that subsequent expansion attempts will also fail if one fails). 240 // Currently, it is only consulted during GC and it's reset at the 241 // start of each GC. 242 bool _expand_heap_after_alloc_failure; 243 244 // Helper for monitoring and management support. 245 G1MonitoringSupport* _g1mm; 246 247 // Records whether the region at the given index is (still) a 248 // candidate for eager reclaim. Only valid for humongous start 249 // regions; other regions have unspecified values. Humongous start 250 // regions are initialized at start of collection pause, with 251 // candidates removed from the set as they are found reachable from 252 // roots or the young generation. 253 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 254 protected: 255 bool default_value() const { return false; } 256 public: 257 void clear() { G1BiasedMappedArray<bool>::clear(); } 258 void set_candidate(uint region, bool value) { 259 set_by_index(region, value); 260 } 261 bool is_candidate(uint region) { 262 return get_by_index(region); 263 } 264 }; 265 266 HumongousReclaimCandidates _humongous_reclaim_candidates; 267 // Stores whether during humongous object registration we found candidate regions. 268 // If not, we can skip a few steps. 269 bool _has_humongous_reclaim_candidates; 270 271 G1HRPrinter _hr_printer; 272 273 // It decides whether an explicit GC should start a concurrent cycle 274 // instead of doing a STW GC. Currently, a concurrent cycle is 275 // explicitly started if: 276 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 277 // (b) cause == _g1_humongous_allocation 278 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 279 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 280 // (e) cause == _wb_conc_mark 281 bool should_do_concurrent_full_gc(GCCause::Cause cause); 282 283 // indicates whether we are in young or mixed GC mode 284 G1CollectorState _collector_state; 285 286 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 287 // concurrent cycles) we have started. 288 volatile uint _old_marking_cycles_started; 289 290 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 291 // concurrent cycles) we have completed. 292 volatile uint _old_marking_cycles_completed; 293 294 // This is a non-product method that is helpful for testing. It is 295 // called at the end of a GC and artificially expands the heap by 296 // allocating a number of dead regions. This way we can induce very 297 // frequent marking cycles and stress the cleanup / concurrent 298 // cleanup code more (as all the regions that will be allocated by 299 // this method will be found dead by the marking cycle). 300 void allocate_dummy_regions() PRODUCT_RETURN; 301 302 // If the HR printer is active, dump the state of the regions in the 303 // heap after a compaction. 304 void print_hrm_post_compaction(); 305 306 // Create a memory mapper for auxiliary data structures of the given size and 307 // translation factor. 308 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 309 size_t size, 310 size_t translation_factor); 311 312 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 313 314 // These are macros so that, if the assert fires, we get the correct 315 // line number, file, etc. 316 317 #define heap_locking_asserts_params(_extra_message_) \ 318 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 319 (_extra_message_), \ 320 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 321 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 322 BOOL_TO_STR(Thread::current()->is_VM_thread()) 323 324 #define assert_heap_locked() \ 325 do { \ 326 assert(Heap_lock->owned_by_self(), \ 327 heap_locking_asserts_params("should be holding the Heap_lock")); \ 328 } while (0) 329 330 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 331 do { \ 332 assert(Heap_lock->owned_by_self() || \ 333 (SafepointSynchronize::is_at_safepoint() && \ 334 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 335 heap_locking_asserts_params("should be holding the Heap_lock or " \ 336 "should be at a safepoint")); \ 337 } while (0) 338 339 #define assert_heap_locked_and_not_at_safepoint() \ 340 do { \ 341 assert(Heap_lock->owned_by_self() && \ 342 !SafepointSynchronize::is_at_safepoint(), \ 343 heap_locking_asserts_params("should be holding the Heap_lock and " \ 344 "should not be at a safepoint")); \ 345 } while (0) 346 347 #define assert_heap_not_locked() \ 348 do { \ 349 assert(!Heap_lock->owned_by_self(), \ 350 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 351 } while (0) 352 353 #define assert_heap_not_locked_and_not_at_safepoint() \ 354 do { \ 355 assert(!Heap_lock->owned_by_self() && \ 356 !SafepointSynchronize::is_at_safepoint(), \ 357 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 358 "should not be at a safepoint")); \ 359 } while (0) 360 361 #define assert_at_safepoint_on_vm_thread() \ 362 do { \ 363 assert_at_safepoint(); \ 364 assert(Thread::current_or_null() != NULL, "no current thread"); \ 365 assert(Thread::current()->is_VM_thread(), "current thread is not VM thread"); \ 366 } while (0) 367 368 // The young region list. 369 G1EdenRegions _eden; 370 G1SurvivorRegions _survivor; 371 372 STWGCTimer* _gc_timer_stw; 373 374 G1NewTracer* _gc_tracer_stw; 375 376 // The current policy object for the collector. 377 G1Policy* _g1_policy; 378 G1HeapSizingPolicy* _heap_sizing_policy; 379 380 G1CollectionSet _collection_set; 381 382 // Try to allocate a single non-humongous HeapRegion sufficient for 383 // an allocation of the given word_size. If do_expand is true, 384 // attempt to expand the heap if necessary to satisfy the allocation 385 // request. If the region is to be used as an old region or for a 386 // humongous object, set is_old to true. If not, to false. 387 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 388 389 // Initialize a contiguous set of free regions of length num_regions 390 // and starting at index first so that they appear as a single 391 // humongous region. 392 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 393 uint num_regions, 394 size_t word_size); 395 396 // Attempt to allocate a humongous object of the given size. Return 397 // NULL if unsuccessful. 398 HeapWord* humongous_obj_allocate(size_t word_size); 399 400 // The following two methods, allocate_new_tlab() and 401 // mem_allocate(), are the two main entry points from the runtime 402 // into the G1's allocation routines. They have the following 403 // assumptions: 404 // 405 // * They should both be called outside safepoints. 406 // 407 // * They should both be called without holding the Heap_lock. 408 // 409 // * All allocation requests for new TLABs should go to 410 // allocate_new_tlab(). 411 // 412 // * All non-TLAB allocation requests should go to mem_allocate(). 413 // 414 // * If either call cannot satisfy the allocation request using the 415 // current allocating region, they will try to get a new one. If 416 // this fails, they will attempt to do an evacuation pause and 417 // retry the allocation. 418 // 419 // * If all allocation attempts fail, even after trying to schedule 420 // an evacuation pause, allocate_new_tlab() will return NULL, 421 // whereas mem_allocate() will attempt a heap expansion and/or 422 // schedule a Full GC. 423 // 424 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 425 // should never be called with word_size being humongous. All 426 // humongous allocation requests should go to mem_allocate() which 427 // will satisfy them with a special path. 428 429 virtual HeapWord* allocate_new_tlab(size_t min_size, 430 size_t requested_size, 431 size_t* actual_size); 432 433 virtual HeapWord* mem_allocate(size_t word_size, 434 bool* gc_overhead_limit_was_exceeded); 435 436 // First-level mutator allocation attempt: try to allocate out of 437 // the mutator alloc region without taking the Heap_lock. This 438 // should only be used for non-humongous allocations. 439 inline HeapWord* attempt_allocation(size_t min_word_size, 440 size_t desired_word_size, 441 size_t* actual_word_size); 442 443 // Second-level mutator allocation attempt: take the Heap_lock and 444 // retry the allocation attempt, potentially scheduling a GC 445 // pause. This should only be used for non-humongous allocations. 446 HeapWord* attempt_allocation_slow(size_t word_size); 447 448 // Takes the Heap_lock and attempts a humongous allocation. It can 449 // potentially schedule a GC pause. 450 HeapWord* attempt_allocation_humongous(size_t word_size); 451 452 // Allocation attempt that should be called during safepoints (e.g., 453 // at the end of a successful GC). expect_null_mutator_alloc_region 454 // specifies whether the mutator alloc region is expected to be NULL 455 // or not. 456 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 457 bool expect_null_mutator_alloc_region); 458 459 // These methods are the "callbacks" from the G1AllocRegion class. 460 461 // For mutator alloc regions. 462 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 463 void retire_mutator_alloc_region(HeapRegion* alloc_region, 464 size_t allocated_bytes); 465 466 // For GC alloc regions. 467 bool has_more_regions(InCSetState dest); 468 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest); 469 void retire_gc_alloc_region(HeapRegion* alloc_region, 470 size_t allocated_bytes, InCSetState dest); 471 472 // - if explicit_gc is true, the GC is for a System.gc() etc, 473 // otherwise it's for a failed allocation. 474 // - if clear_all_soft_refs is true, all soft references should be 475 // cleared during the GC. 476 // - it returns false if it is unable to do the collection due to the 477 // GC locker being active, true otherwise. 478 bool do_full_collection(bool explicit_gc, 479 bool clear_all_soft_refs); 480 481 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 482 virtual void do_full_collection(bool clear_all_soft_refs); 483 484 // Resize the heap if necessary after a full collection. 485 void resize_if_necessary_after_full_collection(); 486 487 // Callback from VM_G1CollectForAllocation operation. 488 // This function does everything necessary/possible to satisfy a 489 // failed allocation request (including collection, expansion, etc.) 490 HeapWord* satisfy_failed_allocation(size_t word_size, 491 bool* succeeded); 492 // Internal helpers used during full GC to split it up to 493 // increase readability. 494 void abort_concurrent_cycle(); 495 void verify_before_full_collection(bool explicit_gc); 496 void prepare_heap_for_full_collection(); 497 void prepare_heap_for_mutators(); 498 void abort_refinement(); 499 void verify_after_full_collection(); 500 void print_heap_after_full_collection(G1HeapTransition* heap_transition); 501 502 // Helper method for satisfy_failed_allocation() 503 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 504 bool do_gc, 505 bool clear_all_soft_refs, 506 bool expect_null_mutator_alloc_region, 507 bool* gc_succeeded); 508 509 // Attempting to expand the heap sufficiently 510 // to support an allocation of the given "word_size". If 511 // successful, perform the allocation and return the address of the 512 // allocated block, or else "NULL". 513 HeapWord* expand_and_allocate(size_t word_size); 514 515 // Process any reference objects discovered. 516 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 517 518 // If during an initial mark pause we may install a pending list head which is not 519 // otherwise reachable ensure that it is marked in the bitmap for concurrent marking 520 // to discover. 521 void make_pending_list_reachable(); 522 523 // Merges the information gathered on a per-thread basis for all worker threads 524 // during GC into global variables. 525 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states); 526 public: 527 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; } 528 529 WorkGang* workers() const { return _workers; } 530 531 G1Allocator* allocator() { 532 return _allocator; 533 } 534 535 G1HeapVerifier* verifier() { 536 return _verifier; 537 } 538 539 G1MonitoringSupport* g1mm() { 540 assert(_g1mm != NULL, "should have been initialized"); 541 return _g1mm; 542 } 543 544 // Expand the garbage-first heap by at least the given size (in bytes!). 545 // Returns true if the heap was expanded by the requested amount; 546 // false otherwise. 547 // (Rounds up to a HeapRegion boundary.) 548 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL); 549 550 // Returns the PLAB statistics for a given destination. 551 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 552 553 // Determines PLAB size for a given destination. 554 inline size_t desired_plab_sz(InCSetState dest); 555 556 // Do anything common to GC's. 557 void gc_prologue(bool full); 558 void gc_epilogue(bool full); 559 560 // Does the given region fulfill remembered set based eager reclaim candidate requirements? 561 bool is_potential_eager_reclaim_candidate(HeapRegion* r) const; 562 563 // Modify the reclaim candidate set and test for presence. 564 // These are only valid for starts_humongous regions. 565 inline void set_humongous_reclaim_candidate(uint region, bool value); 566 inline bool is_humongous_reclaim_candidate(uint region); 567 568 // Remove from the reclaim candidate set. Also remove from the 569 // collection set so that later encounters avoid the slow path. 570 inline void set_humongous_is_live(oop obj); 571 572 // Register the given region to be part of the collection set. 573 inline void register_humongous_region_with_cset(uint index); 574 // Register regions with humongous objects (actually on the start region) in 575 // the in_cset_fast_test table. 576 void register_humongous_regions_with_cset(); 577 // We register a region with the fast "in collection set" test. We 578 // simply set to true the array slot corresponding to this region. 579 void register_young_region_with_cset(HeapRegion* r) { 580 _in_cset_fast_test.set_in_young(r->hrm_index()); 581 } 582 void register_old_region_with_cset(HeapRegion* r) { 583 _in_cset_fast_test.set_in_old(r->hrm_index()); 584 } 585 void clear_in_cset(const HeapRegion* hr) { 586 _in_cset_fast_test.clear(hr); 587 } 588 589 void clear_cset_fast_test() { 590 _in_cset_fast_test.clear(); 591 } 592 593 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 594 595 // This is called at the start of either a concurrent cycle or a Full 596 // GC to update the number of old marking cycles started. 597 void increment_old_marking_cycles_started(); 598 599 // This is called at the end of either a concurrent cycle or a Full 600 // GC to update the number of old marking cycles completed. Those two 601 // can happen in a nested fashion, i.e., we start a concurrent 602 // cycle, a Full GC happens half-way through it which ends first, 603 // and then the cycle notices that a Full GC happened and ends 604 // too. The concurrent parameter is a boolean to help us do a bit 605 // tighter consistency checking in the method. If concurrent is 606 // false, the caller is the inner caller in the nesting (i.e., the 607 // Full GC). If concurrent is true, the caller is the outer caller 608 // in this nesting (i.e., the concurrent cycle). Further nesting is 609 // not currently supported. The end of this call also notifies 610 // the FullGCCount_lock in case a Java thread is waiting for a full 611 // GC to happen (e.g., it called System.gc() with 612 // +ExplicitGCInvokesConcurrent). 613 void increment_old_marking_cycles_completed(bool concurrent); 614 615 uint old_marking_cycles_completed() { 616 return _old_marking_cycles_completed; 617 } 618 619 G1HRPrinter* hr_printer() { return &_hr_printer; } 620 621 // Allocates a new heap region instance. 622 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 623 624 // Allocate the highest free region in the reserved heap. This will commit 625 // regions as necessary. 626 HeapRegion* alloc_highest_free_region(); 627 628 // Frees a non-humongous region by initializing its contents and 629 // adding it to the free list that's passed as a parameter (this is 630 // usually a local list which will be appended to the master free 631 // list later). The used bytes of freed regions are accumulated in 632 // pre_used. If skip_remset is true, the region's RSet will not be freed 633 // up. If skip_hot_card_cache is true, the region's hot card cache will not 634 // be freed up. The assumption is that this will be done later. 635 // The locked parameter indicates if the caller has already taken 636 // care of proper synchronization. This may allow some optimizations. 637 void free_region(HeapRegion* hr, 638 FreeRegionList* free_list, 639 bool skip_remset, 640 bool skip_hot_card_cache = false, 641 bool locked = false); 642 643 // It dirties the cards that cover the block so that the post 644 // write barrier never queues anything when updating objects on this 645 // block. It is assumed (and in fact we assert) that the block 646 // belongs to a young region. 647 inline void dirty_young_block(HeapWord* start, size_t word_size); 648 649 // Frees a humongous region by collapsing it into individual regions 650 // and calling free_region() for each of them. The freed regions 651 // will be added to the free list that's passed as a parameter (this 652 // is usually a local list which will be appended to the master free 653 // list later). 654 // The method assumes that only a single thread is ever calling 655 // this for a particular region at once. 656 void free_humongous_region(HeapRegion* hr, 657 FreeRegionList* free_list); 658 659 // Facility for allocating in 'archive' regions in high heap memory and 660 // recording the allocated ranges. These should all be called from the 661 // VM thread at safepoints, without the heap lock held. They can be used 662 // to create and archive a set of heap regions which can be mapped at the 663 // same fixed addresses in a subsequent JVM invocation. 664 void begin_archive_alloc_range(bool open = false); 665 666 // Check if the requested size would be too large for an archive allocation. 667 bool is_archive_alloc_too_large(size_t word_size); 668 669 // Allocate memory of the requested size from the archive region. This will 670 // return NULL if the size is too large or if no memory is available. It 671 // does not trigger a garbage collection. 672 HeapWord* archive_mem_allocate(size_t word_size); 673 674 // Optionally aligns the end address and returns the allocated ranges in 675 // an array of MemRegions in order of ascending addresses. 676 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 677 size_t end_alignment_in_bytes = 0); 678 679 // Facility for allocating a fixed range within the heap and marking 680 // the containing regions as 'archive'. For use at JVM init time, when the 681 // caller may mmap archived heap data at the specified range(s). 682 // Verify that the MemRegions specified in the argument array are within the 683 // reserved heap. 684 bool check_archive_addresses(MemRegion* range, size_t count); 685 686 // Commit the appropriate G1 regions containing the specified MemRegions 687 // and mark them as 'archive' regions. The regions in the array must be 688 // non-overlapping and in order of ascending address. 689 bool alloc_archive_regions(MemRegion* range, size_t count, bool open); 690 691 // Insert any required filler objects in the G1 regions around the specified 692 // ranges to make the regions parseable. This must be called after 693 // alloc_archive_regions, and after class loading has occurred. 694 void fill_archive_regions(MemRegion* range, size_t count); 695 696 // For each of the specified MemRegions, uncommit the containing G1 regions 697 // which had been allocated by alloc_archive_regions. This should be called 698 // rather than fill_archive_regions at JVM init time if the archive file 699 // mapping failed, with the same non-overlapping and sorted MemRegion array. 700 void dealloc_archive_regions(MemRegion* range, size_t count, bool is_open); 701 702 oop materialize_archived_object(oop obj); 703 704 private: 705 706 // Shrink the garbage-first heap by at most the given size (in bytes!). 707 // (Rounds down to a HeapRegion boundary.) 708 void shrink(size_t expand_bytes); 709 void shrink_helper(size_t expand_bytes); 710 711 #if TASKQUEUE_STATS 712 static void print_taskqueue_stats_hdr(outputStream* const st); 713 void print_taskqueue_stats() const; 714 void reset_taskqueue_stats(); 715 #endif // TASKQUEUE_STATS 716 717 // Schedule the VM operation that will do an evacuation pause to 718 // satisfy an allocation request of word_size. *succeeded will 719 // return whether the VM operation was successful (it did do an 720 // evacuation pause) or not (another thread beat us to it or the GC 721 // locker was active). Given that we should not be holding the 722 // Heap_lock when we enter this method, we will pass the 723 // gc_count_before (i.e., total_collections()) as a parameter since 724 // it has to be read while holding the Heap_lock. Currently, both 725 // methods that call do_collection_pause() release the Heap_lock 726 // before the call, so it's easy to read gc_count_before just before. 727 HeapWord* do_collection_pause(size_t word_size, 728 uint gc_count_before, 729 bool* succeeded, 730 GCCause::Cause gc_cause); 731 732 void wait_for_root_region_scanning(); 733 734 // The guts of the incremental collection pause, executed by the vm 735 // thread. It returns false if it is unable to do the collection due 736 // to the GC locker being active, true otherwise 737 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 738 739 // Actually do the work of evacuating the collection set. 740 void evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states); 741 742 void pre_evacuate_collection_set(); 743 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 744 745 // Print the header for the per-thread termination statistics. 746 static void print_termination_stats_hdr(); 747 // Print actual per-thread termination statistics. 748 void print_termination_stats(uint worker_id, 749 double elapsed_ms, 750 double strong_roots_ms, 751 double term_ms, 752 size_t term_attempts, 753 size_t alloc_buffer_waste, 754 size_t undo_waste) const; 755 // Update object copying statistics. 756 void record_obj_copy_mem_stats(); 757 758 // The hot card cache for remembered set insertion optimization. 759 G1HotCardCache* _hot_card_cache; 760 761 // The g1 remembered set of the heap. 762 G1RemSet* _g1_rem_set; 763 764 // A set of cards that cover the objects for which the Rsets should be updated 765 // concurrently after the collection. 766 DirtyCardQueueSet _dirty_card_queue_set; 767 768 // After a collection pause, convert the regions in the collection set into free 769 // regions. 770 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 771 772 // Abandon the current collection set without recording policy 773 // statistics or updating free lists. 774 void abandon_collection_set(G1CollectionSet* collection_set); 775 776 // The concurrent marker (and the thread it runs in.) 777 G1ConcurrentMark* _cm; 778 G1ConcurrentMarkThread* _cm_thread; 779 780 // The concurrent refiner. 781 G1ConcurrentRefine* _cr; 782 783 // The parallel task queues 784 RefToScanQueueSet *_task_queues; 785 786 // True iff a evacuation has failed in the current collection. 787 bool _evacuation_failed; 788 789 EvacuationFailedInfo* _evacuation_failed_info_array; 790 791 // Failed evacuations cause some logical from-space objects to have 792 // forwarding pointers to themselves. Reset them. 793 void remove_self_forwarding_pointers(); 794 795 // Restore the objects in the regions in the collection set after an 796 // evacuation failure. 797 void restore_after_evac_failure(); 798 799 PreservedMarksSet _preserved_marks_set; 800 801 // Preserve the mark of "obj", if necessary, in preparation for its mark 802 // word being overwritten with a self-forwarding-pointer. 803 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 804 805 #ifndef PRODUCT 806 // Support for forcing evacuation failures. Analogous to 807 // PromotionFailureALot for the other collectors. 808 809 // Records whether G1EvacuationFailureALot should be in effect 810 // for the current GC 811 bool _evacuation_failure_alot_for_current_gc; 812 813 // Used to record the GC number for interval checking when 814 // determining whether G1EvaucationFailureALot is in effect 815 // for the current GC. 816 size_t _evacuation_failure_alot_gc_number; 817 818 // Count of the number of evacuations between failures. 819 volatile size_t _evacuation_failure_alot_count; 820 821 // Set whether G1EvacuationFailureALot should be in effect 822 // for the current GC (based upon the type of GC and which 823 // command line flags are set); 824 inline bool evacuation_failure_alot_for_gc_type(bool for_young_gc, 825 bool during_initial_mark, 826 bool mark_or_rebuild_in_progress); 827 828 inline void set_evacuation_failure_alot_for_current_gc(); 829 830 // Return true if it's time to cause an evacuation failure. 831 inline bool evacuation_should_fail(); 832 833 // Reset the G1EvacuationFailureALot counters. Should be called at 834 // the end of an evacuation pause in which an evacuation failure occurred. 835 inline void reset_evacuation_should_fail(); 836 #endif // !PRODUCT 837 838 // ("Weak") Reference processing support. 839 // 840 // G1 has 2 instances of the reference processor class. One 841 // (_ref_processor_cm) handles reference object discovery 842 // and subsequent processing during concurrent marking cycles. 843 // 844 // The other (_ref_processor_stw) handles reference object 845 // discovery and processing during full GCs and incremental 846 // evacuation pauses. 847 // 848 // During an incremental pause, reference discovery will be 849 // temporarily disabled for _ref_processor_cm and will be 850 // enabled for _ref_processor_stw. At the end of the evacuation 851 // pause references discovered by _ref_processor_stw will be 852 // processed and discovery will be disabled. The previous 853 // setting for reference object discovery for _ref_processor_cm 854 // will be re-instated. 855 // 856 // At the start of marking: 857 // * Discovery by the CM ref processor is verified to be inactive 858 // and it's discovered lists are empty. 859 // * Discovery by the CM ref processor is then enabled. 860 // 861 // At the end of marking: 862 // * Any references on the CM ref processor's discovered 863 // lists are processed (possibly MT). 864 // 865 // At the start of full GC we: 866 // * Disable discovery by the CM ref processor and 867 // empty CM ref processor's discovered lists 868 // (without processing any entries). 869 // * Verify that the STW ref processor is inactive and it's 870 // discovered lists are empty. 871 // * Temporarily set STW ref processor discovery as single threaded. 872 // * Temporarily clear the STW ref processor's _is_alive_non_header 873 // field. 874 // * Finally enable discovery by the STW ref processor. 875 // 876 // The STW ref processor is used to record any discovered 877 // references during the full GC. 878 // 879 // At the end of a full GC we: 880 // * Enqueue any reference objects discovered by the STW ref processor 881 // that have non-live referents. This has the side-effect of 882 // making the STW ref processor inactive by disabling discovery. 883 // * Verify that the CM ref processor is still inactive 884 // and no references have been placed on it's discovered 885 // lists (also checked as a precondition during initial marking). 886 887 // The (stw) reference processor... 888 ReferenceProcessor* _ref_processor_stw; 889 890 // During reference object discovery, the _is_alive_non_header 891 // closure (if non-null) is applied to the referent object to 892 // determine whether the referent is live. If so then the 893 // reference object does not need to be 'discovered' and can 894 // be treated as a regular oop. This has the benefit of reducing 895 // the number of 'discovered' reference objects that need to 896 // be processed. 897 // 898 // Instance of the is_alive closure for embedding into the 899 // STW reference processor as the _is_alive_non_header field. 900 // Supplying a value for the _is_alive_non_header field is 901 // optional but doing so prevents unnecessary additions to 902 // the discovered lists during reference discovery. 903 G1STWIsAliveClosure _is_alive_closure_stw; 904 905 G1STWSubjectToDiscoveryClosure _is_subject_to_discovery_stw; 906 907 // The (concurrent marking) reference processor... 908 ReferenceProcessor* _ref_processor_cm; 909 910 // Instance of the concurrent mark is_alive closure for embedding 911 // into the Concurrent Marking reference processor as the 912 // _is_alive_non_header field. Supplying a value for the 913 // _is_alive_non_header field is optional but doing so prevents 914 // unnecessary additions to the discovered lists during reference 915 // discovery. 916 G1CMIsAliveClosure _is_alive_closure_cm; 917 918 G1CMSubjectToDiscoveryClosure _is_subject_to_discovery_cm; 919 public: 920 921 RefToScanQueue *task_queue(uint i) const; 922 923 uint num_task_queues() const; 924 925 // A set of cards where updates happened during the GC 926 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 927 928 // Create a G1CollectedHeap with the specified policy. 929 // Must call the initialize method afterwards. 930 // May not return if something goes wrong. 931 G1CollectedHeap(G1CollectorPolicy* policy); 932 933 private: 934 jint initialize_concurrent_refinement(); 935 jint initialize_young_gen_sampling_thread(); 936 public: 937 // Initialize the G1CollectedHeap to have the initial and 938 // maximum sizes and remembered and barrier sets 939 // specified by the policy object. 940 jint initialize(); 941 942 virtual void stop(); 943 virtual void safepoint_synchronize_begin(); 944 virtual void safepoint_synchronize_end(); 945 946 // Return the (conservative) maximum heap alignment for any G1 heap 947 static size_t conservative_max_heap_alignment(); 948 949 // Does operations required after initialization has been done. 950 void post_initialize(); 951 952 // Initialize weak reference processing. 953 void ref_processing_init(); 954 955 virtual Name kind() const { 956 return CollectedHeap::G1; 957 } 958 959 virtual const char* name() const { 960 return "G1"; 961 } 962 963 const G1CollectorState* collector_state() const { return &_collector_state; } 964 G1CollectorState* collector_state() { return &_collector_state; } 965 966 // The current policy object for the collector. 967 G1Policy* g1_policy() const { return _g1_policy; } 968 969 const G1CollectionSet* collection_set() const { return &_collection_set; } 970 G1CollectionSet* collection_set() { return &_collection_set; } 971 972 virtual CollectorPolicy* collector_policy() const; 973 974 virtual SoftRefPolicy* soft_ref_policy(); 975 976 virtual GrowableArray<GCMemoryManager*> memory_managers(); 977 virtual GrowableArray<MemoryPool*> memory_pools(); 978 979 // The rem set and barrier set. 980 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 981 982 // Try to minimize the remembered set. 983 void scrub_rem_set(); 984 985 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 986 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i); 987 988 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. 989 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i); 990 991 // The shared block offset table array. 992 G1BlockOffsetTable* bot() const { return _bot; } 993 994 // Reference Processing accessors 995 996 // The STW reference processor.... 997 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 998 999 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1000 1001 // The Concurrent Marking reference processor... 1002 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1003 1004 size_t unused_committed_regions_in_bytes() const; 1005 virtual size_t capacity() const; 1006 virtual size_t used() const; 1007 // This should be called when we're not holding the heap lock. The 1008 // result might be a bit inaccurate. 1009 size_t used_unlocked() const; 1010 size_t recalculate_used() const; 1011 1012 // These virtual functions do the actual allocation. 1013 // Some heaps may offer a contiguous region for shared non-blocking 1014 // allocation, via inlined code (by exporting the address of the top and 1015 // end fields defining the extent of the contiguous allocation region.) 1016 // But G1CollectedHeap doesn't yet support this. 1017 1018 virtual bool is_maximal_no_gc() const { 1019 return _hrm.available() == 0; 1020 } 1021 1022 // Returns whether there are any regions left in the heap for allocation. 1023 bool has_regions_left_for_allocation() const { 1024 return !is_maximal_no_gc() || num_free_regions() != 0; 1025 } 1026 1027 // The current number of regions in the heap. 1028 uint num_regions() const { return _hrm.length(); } 1029 1030 // The max number of regions in the heap. 1031 uint max_regions() const { return _hrm.max_length(); } 1032 1033 // The number of regions that are completely free. 1034 uint num_free_regions() const { return _hrm.num_free_regions(); } 1035 1036 MemoryUsage get_auxiliary_data_memory_usage() const { 1037 return _hrm.get_auxiliary_data_memory_usage(); 1038 } 1039 1040 // The number of regions that are not completely free. 1041 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1042 1043 #ifdef ASSERT 1044 bool is_on_master_free_list(HeapRegion* hr) { 1045 return _hrm.is_free(hr); 1046 } 1047 #endif // ASSERT 1048 1049 inline void old_set_add(HeapRegion* hr); 1050 inline void old_set_remove(HeapRegion* hr); 1051 1052 size_t non_young_capacity_bytes() { 1053 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes; 1054 } 1055 1056 // Determine whether the given region is one that we are using as an 1057 // old GC alloc region. 1058 bool is_old_gc_alloc_region(HeapRegion* hr); 1059 1060 // Perform a collection of the heap; intended for use in implementing 1061 // "System.gc". This probably implies as full a collection as the 1062 // "CollectedHeap" supports. 1063 virtual void collect(GCCause::Cause cause); 1064 1065 // True iff an evacuation has failed in the most-recent collection. 1066 bool evacuation_failed() { return _evacuation_failed; } 1067 1068 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed); 1069 void prepend_to_freelist(FreeRegionList* list); 1070 void decrement_summary_bytes(size_t bytes); 1071 1072 virtual bool is_in(const void* p) const; 1073 #ifdef ASSERT 1074 // Returns whether p is in one of the available areas of the heap. Slow but 1075 // extensive version. 1076 bool is_in_exact(const void* p) const; 1077 #endif 1078 1079 // Return "TRUE" iff the given object address is within the collection 1080 // set. Assumes that the reference points into the heap. 1081 inline bool is_in_cset(const HeapRegion *hr); 1082 inline bool is_in_cset(oop obj); 1083 inline bool is_in_cset(HeapWord* addr); 1084 1085 inline bool is_in_cset_or_humongous(const oop obj); 1086 1087 private: 1088 // This array is used for a quick test on whether a reference points into 1089 // the collection set or not. Each of the array's elements denotes whether the 1090 // corresponding region is in the collection set or not. 1091 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1092 1093 public: 1094 1095 inline InCSetState in_cset_state(const oop obj); 1096 1097 // Return "TRUE" iff the given object address is in the reserved 1098 // region of g1. 1099 bool is_in_g1_reserved(const void* p) const { 1100 return _hrm.reserved().contains(p); 1101 } 1102 1103 // Returns a MemRegion that corresponds to the space that has been 1104 // reserved for the heap 1105 MemRegion g1_reserved() const { 1106 return _hrm.reserved(); 1107 } 1108 1109 virtual bool is_in_closed_subset(const void* p) const; 1110 1111 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; } 1112 1113 G1CardTable* card_table() const { 1114 return _card_table; 1115 } 1116 1117 // Iteration functions. 1118 1119 // Iterate over all objects, calling "cl.do_object" on each. 1120 virtual void object_iterate(ObjectClosure* cl); 1121 1122 virtual void safe_object_iterate(ObjectClosure* cl) { 1123 object_iterate(cl); 1124 } 1125 1126 // Iterate over heap regions, in address order, terminating the 1127 // iteration early if the "do_heap_region" method returns "true". 1128 void heap_region_iterate(HeapRegionClosure* blk) const; 1129 1130 // Return the region with the given index. It assumes the index is valid. 1131 inline HeapRegion* region_at(uint index) const; 1132 1133 // Return the next region (by index) that is part of the same 1134 // humongous object that hr is part of. 1135 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1136 1137 // Calculate the region index of the given address. Given address must be 1138 // within the heap. 1139 inline uint addr_to_region(HeapWord* addr) const; 1140 1141 inline HeapWord* bottom_addr_for_region(uint index) const; 1142 1143 // Two functions to iterate over the heap regions in parallel. Threads 1144 // compete using the HeapRegionClaimer to claim the regions before 1145 // applying the closure on them. 1146 // The _from_worker_offset version uses the HeapRegionClaimer and 1147 // the worker id to calculate a start offset to prevent all workers to 1148 // start from the point. 1149 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 1150 HeapRegionClaimer* hrclaimer, 1151 uint worker_id) const; 1152 1153 void heap_region_par_iterate_from_start(HeapRegionClosure* cl, 1154 HeapRegionClaimer* hrclaimer) const; 1155 1156 // Iterate over the regions (if any) in the current collection set. 1157 void collection_set_iterate(HeapRegionClosure* blk); 1158 1159 // Iterate over the regions (if any) in the current collection set. Starts the 1160 // iteration over the entire collection set so that the start regions of a given 1161 // worker id over the set active_workers are evenly spread across the set of 1162 // collection set regions. 1163 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id); 1164 1165 // Returns the HeapRegion that contains addr. addr must not be NULL. 1166 template <class T> 1167 inline HeapRegion* heap_region_containing(const T addr) const; 1168 1169 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1170 // each address in the (reserved) heap is a member of exactly 1171 // one block. The defining characteristic of a block is that it is 1172 // possible to find its size, and thus to progress forward to the next 1173 // block. (Blocks may be of different sizes.) Thus, blocks may 1174 // represent Java objects, or they might be free blocks in a 1175 // free-list-based heap (or subheap), as long as the two kinds are 1176 // distinguishable and the size of each is determinable. 1177 1178 // Returns the address of the start of the "block" that contains the 1179 // address "addr". We say "blocks" instead of "object" since some heaps 1180 // may not pack objects densely; a chunk may either be an object or a 1181 // non-object. 1182 virtual HeapWord* block_start(const void* addr) const; 1183 1184 // Requires "addr" to be the start of a chunk, and returns its size. 1185 // "addr + size" is required to be the start of a new chunk, or the end 1186 // of the active area of the heap. 1187 virtual size_t block_size(const HeapWord* addr) const; 1188 1189 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1190 // the block is an object. 1191 virtual bool block_is_obj(const HeapWord* addr) const; 1192 1193 // Section on thread-local allocation buffers (TLABs) 1194 // See CollectedHeap for semantics. 1195 1196 bool supports_tlab_allocation() const; 1197 size_t tlab_capacity(Thread* ignored) const; 1198 size_t tlab_used(Thread* ignored) const; 1199 size_t max_tlab_size() const; 1200 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1201 1202 inline bool is_in_young(const oop obj); 1203 1204 // Returns "true" iff the given word_size is "very large". 1205 static bool is_humongous(size_t word_size) { 1206 // Note this has to be strictly greater-than as the TLABs 1207 // are capped at the humongous threshold and we want to 1208 // ensure that we don't try to allocate a TLAB as 1209 // humongous and that we don't allocate a humongous 1210 // object in a TLAB. 1211 return word_size > _humongous_object_threshold_in_words; 1212 } 1213 1214 // Returns the humongous threshold for a specific region size 1215 static size_t humongous_threshold_for(size_t region_size) { 1216 return (region_size / 2); 1217 } 1218 1219 // Returns the number of regions the humongous object of the given word size 1220 // requires. 1221 static size_t humongous_obj_size_in_regions(size_t word_size); 1222 1223 // Print the maximum heap capacity. 1224 virtual size_t max_capacity() const; 1225 1226 virtual jlong millis_since_last_gc(); 1227 1228 1229 // Convenience function to be used in situations where the heap type can be 1230 // asserted to be this type. 1231 static G1CollectedHeap* heap(); 1232 1233 void set_region_short_lived_locked(HeapRegion* hr); 1234 // add appropriate methods for any other surv rate groups 1235 1236 const G1SurvivorRegions* survivor() const { return &_survivor; } 1237 1238 uint survivor_regions_count() const { 1239 return _survivor.length(); 1240 } 1241 1242 uint eden_regions_count() const { 1243 return _eden.length(); 1244 } 1245 1246 uint young_regions_count() const { 1247 return _eden.length() + _survivor.length(); 1248 } 1249 1250 uint old_regions_count() const { return _old_set.length(); } 1251 1252 uint humongous_regions_count() const { return _humongous_set.length(); } 1253 1254 #ifdef ASSERT 1255 bool check_young_list_empty(); 1256 #endif 1257 1258 // *** Stuff related to concurrent marking. It's not clear to me that so 1259 // many of these need to be public. 1260 1261 // The functions below are helper functions that a subclass of 1262 // "CollectedHeap" can use in the implementation of its virtual 1263 // functions. 1264 // This performs a concurrent marking of the live objects in a 1265 // bitmap off to the side. 1266 void do_concurrent_mark(); 1267 1268 bool is_marked_next(oop obj) const; 1269 1270 // Determine if an object is dead, given the object and also 1271 // the region to which the object belongs. An object is dead 1272 // iff a) it was not allocated since the last mark, b) it 1273 // is not marked, and c) it is not in an archive region. 1274 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1275 return 1276 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) && 1277 !hr->is_archive(); 1278 } 1279 1280 // This function returns true when an object has been 1281 // around since the previous marking and hasn't yet 1282 // been marked during this marking, and is not in an archive region. 1283 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1284 return 1285 !hr->obj_allocated_since_next_marking(obj) && 1286 !is_marked_next(obj) && 1287 !hr->is_archive(); 1288 } 1289 1290 // Determine if an object is dead, given only the object itself. 1291 // This will find the region to which the object belongs and 1292 // then call the region version of the same function. 1293 1294 // Added if it is NULL it isn't dead. 1295 1296 inline bool is_obj_dead(const oop obj) const; 1297 1298 inline bool is_obj_ill(const oop obj) const; 1299 1300 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const; 1301 inline bool is_obj_dead_full(const oop obj) const; 1302 1303 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1304 1305 // Refinement 1306 1307 G1ConcurrentRefine* concurrent_refine() const { return _cr; } 1308 1309 // Optimized nmethod scanning support routines 1310 1311 // Is an oop scavengeable 1312 virtual bool is_scavengable(oop obj); 1313 1314 // Register the given nmethod with the G1 heap. 1315 virtual void register_nmethod(nmethod* nm); 1316 1317 // Unregister the given nmethod from the G1 heap. 1318 virtual void unregister_nmethod(nmethod* nm); 1319 1320 // Free up superfluous code root memory. 1321 void purge_code_root_memory(); 1322 1323 // Rebuild the strong code root lists for each region 1324 // after a full GC. 1325 void rebuild_strong_code_roots(); 1326 1327 // Partial cleaning used when class unloading is disabled. 1328 // Let the caller choose what structures to clean out: 1329 // - StringTable 1330 // - SymbolTable 1331 // - StringDeduplication structures 1332 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup); 1333 1334 // Complete cleaning used when class unloading is enabled. 1335 // Cleans out all structures handled by partial_cleaning and also the CodeCache. 1336 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); 1337 1338 // Redirty logged cards in the refinement queue. 1339 void redirty_logged_cards(); 1340 // Verification 1341 1342 // Deduplicate the string 1343 virtual void deduplicate_string(oop str); 1344 1345 // Perform any cleanup actions necessary before allowing a verification. 1346 virtual void prepare_for_verify(); 1347 1348 // Perform verification. 1349 1350 // vo == UsePrevMarking -> use "prev" marking information, 1351 // vo == UseNextMarking -> use "next" marking information 1352 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS 1353 // 1354 // NOTE: Only the "prev" marking information is guaranteed to be 1355 // consistent most of the time, so most calls to this should use 1356 // vo == UsePrevMarking. 1357 // Currently, there is only one case where this is called with 1358 // vo == UseNextMarking, which is to verify the "next" marking 1359 // information at the end of remark. 1360 // Currently there is only one place where this is called with 1361 // vo == UseFullMarking, which is to verify the marking during a 1362 // full GC. 1363 void verify(VerifyOption vo); 1364 1365 // WhiteBox testing support. 1366 virtual bool supports_concurrent_phase_control() const; 1367 virtual const char* const* concurrent_phases() const; 1368 virtual bool request_concurrent_phase(const char* phase); 1369 1370 virtual WorkGang* get_safepoint_workers() { return _workers; } 1371 1372 // The methods below are here for convenience and dispatch the 1373 // appropriate method depending on value of the given VerifyOption 1374 // parameter. The values for that parameter, and their meanings, 1375 // are the same as those above. 1376 1377 bool is_obj_dead_cond(const oop obj, 1378 const HeapRegion* hr, 1379 const VerifyOption vo) const; 1380 1381 bool is_obj_dead_cond(const oop obj, 1382 const VerifyOption vo) const; 1383 1384 G1HeapSummary create_g1_heap_summary(); 1385 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1386 1387 // Printing 1388 private: 1389 void print_heap_regions() const; 1390 void print_regions_on(outputStream* st) const; 1391 1392 public: 1393 virtual void print_on(outputStream* st) const; 1394 virtual void print_extended_on(outputStream* st) const; 1395 virtual void print_on_error(outputStream* st) const; 1396 1397 virtual void print_gc_threads_on(outputStream* st) const; 1398 virtual void gc_threads_do(ThreadClosure* tc) const; 1399 1400 // Override 1401 void print_tracing_info() const; 1402 1403 // The following two methods are helpful for debugging RSet issues. 1404 void print_cset_rsets() PRODUCT_RETURN; 1405 void print_all_rsets() PRODUCT_RETURN; 1406 1407 public: 1408 size_t pending_card_num(); 1409 1410 private: 1411 size_t _max_heap_capacity; 1412 }; 1413 1414 class G1ParEvacuateFollowersClosure : public VoidClosure { 1415 private: 1416 double _start_term; 1417 double _term_time; 1418 size_t _term_attempts; 1419 1420 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 1421 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 1422 protected: 1423 G1CollectedHeap* _g1h; 1424 G1ParScanThreadState* _par_scan_state; 1425 RefToScanQueueSet* _queues; 1426 ParallelTaskTerminator* _terminator; 1427 1428 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 1429 RefToScanQueueSet* queues() { return _queues; } 1430 ParallelTaskTerminator* terminator() { return _terminator; } 1431 1432 public: 1433 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 1434 G1ParScanThreadState* par_scan_state, 1435 RefToScanQueueSet* queues, 1436 ParallelTaskTerminator* terminator) 1437 : _g1h(g1h), _par_scan_state(par_scan_state), 1438 _queues(queues), _terminator(terminator), 1439 _start_term(0.0), _term_time(0.0), _term_attempts(0) {} 1440 1441 void do_void(); 1442 1443 double term_time() const { return _term_time; } 1444 size_t term_attempts() const { return _term_attempts; } 1445 1446 private: 1447 inline bool offer_termination(); 1448 }; 1449 1450 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP