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