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/g1AllocationContext.hpp" 30 #include "gc/g1/g1BiasedArray.hpp" 31 #include "gc/g1/g1CollectionSet.hpp" 32 #include "gc/g1/g1CollectorState.hpp" 33 #include "gc/g1/g1ConcurrentMark.hpp" 34 #include "gc/g1/g1EdenRegions.hpp" 35 #include "gc/g1/g1EvacFailure.hpp" 36 #include "gc/g1/g1EvacStats.hpp" 37 #include "gc/g1/g1HeapTransition.hpp" 38 #include "gc/g1/g1HeapVerifier.hpp" 39 #include "gc/g1/g1HRPrinter.hpp" 40 #include "gc/g1/g1InCSetState.hpp" 41 #include "gc/g1/g1MonitoringSupport.hpp" 42 #include "gc/g1/g1SATBCardTableModRefBS.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 ConcurrentMarkThread; 83 class G1ConcurrentRefine; 84 class GenerationCounters; 85 class STWGCTimer; 86 class G1NewTracer; 87 class EvacuationFailedInfo; 88 class nmethod; 89 class Ticks; 90 class WorkGang; 91 class G1Allocator; 92 class G1ArchiveAllocator; 93 class G1FullGCScope; 94 class G1HeapVerifier; 95 class G1HeapSizingPolicy; 96 class G1HeapSummary; 97 class G1EvacSummary; 98 99 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 100 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 101 102 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 103 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 104 105 // The G1 STW is alive closure. 106 // An instance is embedded into the G1CH and used as the 107 // (optional) _is_alive_non_header closure in the STW 108 // reference processor. It is also extensively used during 109 // reference processing during STW evacuation pauses. 110 class G1STWIsAliveClosure: public BoolObjectClosure { 111 G1CollectedHeap* _g1; 112 public: 113 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 114 bool do_object_b(oop p); 115 }; 116 117 class G1RegionMappingChangedListener : public G1MappingChangedListener { 118 private: 119 void reset_from_card_cache(uint start_idx, size_t num_regions); 120 public: 121 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 122 }; 123 124 class G1CollectedHeap : public CollectedHeap { 125 friend class G1FreeCollectionSetTask; 126 friend class VM_CollectForMetadataAllocation; 127 friend class VM_G1CollectForAllocation; 128 friend class VM_G1CollectFull; 129 friend class VMStructs; 130 friend class MutatorAllocRegion; 131 friend class G1FullCollector; 132 friend class G1GCAllocRegion; 133 friend class G1HeapVerifier; 134 135 // Closures used in implementation. 136 friend class G1ParScanThreadState; 137 friend class G1ParScanThreadStateSet; 138 friend class G1ParTask; 139 friend class G1PLABAllocator; 140 friend class G1PrepareCompactClosure; 141 142 // Other related classes. 143 friend class HeapRegionClaimer; 144 145 // Testing classes. 146 friend class G1CheckCSetFastTableClosure; 147 148 private: 149 G1YoungRemSetSamplingThread* _young_gen_sampling_thread; 150 151 WorkGang* _workers; 152 G1CollectorPolicy* _collector_policy; 153 154 SoftRefPolicy _soft_ref_policy; 155 156 GCMemoryManager _memory_manager; 157 GCMemoryManager _full_gc_memory_manager; 158 159 MemoryPool* _eden_pool; 160 MemoryPool* _survivor_pool; 161 MemoryPool* _old_pool; 162 163 static size_t _humongous_object_threshold_in_words; 164 165 // The secondary free list which contains regions that have been 166 // freed up during the cleanup process. This will be appended to 167 // the master free list when appropriate. 168 FreeRegionList _secondary_free_list; 169 170 // It keeps track of the old regions. 171 HeapRegionSet _old_set; 172 173 // It keeps track of the humongous regions. 174 HeapRegionSet _humongous_set; 175 176 virtual void initialize_serviceability(); 177 178 void eagerly_reclaim_humongous_regions(); 179 // Start a new incremental collection set for the next pause. 180 void start_new_collection_set(); 181 182 // The number of regions we could create by expansion. 183 uint _expansion_regions; 184 185 // The block offset table for the G1 heap. 186 G1BlockOffsetTable* _bot; 187 188 // Tears down the region sets / lists so that they are empty and the 189 // regions on the heap do not belong to a region set / list. The 190 // only exception is the humongous set which we leave unaltered. If 191 // free_list_only is true, it will only tear down the master free 192 // list. It is called before a Full GC (free_list_only == false) or 193 // before heap shrinking (free_list_only == true). 194 void tear_down_region_sets(bool free_list_only); 195 196 // Rebuilds the region sets / lists so that they are repopulated to 197 // reflect the contents of the heap. The only exception is the 198 // humongous set which was not torn down in the first place. If 199 // free_list_only is true, it will only rebuild the master free 200 // list. It is called after a Full GC (free_list_only == false) or 201 // after heap shrinking (free_list_only == true). 202 void rebuild_region_sets(bool free_list_only); 203 204 // Callback for region mapping changed events. 205 G1RegionMappingChangedListener _listener; 206 207 // The sequence of all heap regions in the heap. 208 HeapRegionManager _hrm; 209 210 // Manages all allocations with regions except humongous object allocations. 211 G1Allocator* _allocator; 212 213 // Manages all heap verification. 214 G1HeapVerifier* _verifier; 215 216 // Outside of GC pauses, the number of bytes used in all regions other 217 // than the current allocation region(s). 218 size_t _summary_bytes_used; 219 220 void increase_used(size_t bytes); 221 void decrease_used(size_t bytes); 222 223 void set_used(size_t bytes); 224 225 // Class that handles archive allocation ranges. 226 G1ArchiveAllocator* _archive_allocator; 227 228 // GC allocation statistics policy for survivors. 229 G1EvacStats _survivor_evac_stats; 230 231 // GC allocation statistics policy for tenured objects. 232 G1EvacStats _old_evac_stats; 233 234 // It specifies whether we should attempt to expand the heap after a 235 // region allocation failure. If heap expansion fails we set this to 236 // false so that we don't re-attempt the heap expansion (it's likely 237 // that subsequent expansion attempts will also fail if one fails). 238 // Currently, it is only consulted during GC and it's reset at the 239 // start of each GC. 240 bool _expand_heap_after_alloc_failure; 241 242 // Helper for monitoring and management support. 243 G1MonitoringSupport* _g1mm; 244 245 // Records whether the region at the given index is (still) a 246 // candidate for eager reclaim. Only valid for humongous start 247 // regions; other regions have unspecified values. Humongous start 248 // regions are initialized at start of collection pause, with 249 // candidates removed from the set as they are found reachable from 250 // roots or the young generation. 251 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 252 protected: 253 bool default_value() const { return false; } 254 public: 255 void clear() { G1BiasedMappedArray<bool>::clear(); } 256 void set_candidate(uint region, bool value) { 257 set_by_index(region, value); 258 } 259 bool is_candidate(uint region) { 260 return get_by_index(region); 261 } 262 }; 263 264 HumongousReclaimCandidates _humongous_reclaim_candidates; 265 // Stores whether during humongous object registration we found candidate regions. 266 // If not, we can skip a few steps. 267 bool _has_humongous_reclaim_candidates; 268 269 volatile uint _gc_time_stamp; 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 // Clear RSets after a compaction. It also resets the GC time stamps. 303 void clear_rsets_post_compaction(); 304 305 // If the HR printer is active, dump the state of the regions in the 306 // heap after a compaction. 307 void print_hrm_post_compaction(); 308 309 // Create a memory mapper for auxiliary data structures of the given size and 310 // translation factor. 311 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 312 size_t size, 313 size_t translation_factor); 314 315 static G1Policy* create_g1_policy(STWGCTimer* gc_timer); 316 317 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 318 319 // These are macros so that, if the assert fires, we get the correct 320 // line number, file, etc. 321 322 #define heap_locking_asserts_params(_extra_message_) \ 323 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 324 (_extra_message_), \ 325 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 326 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 327 BOOL_TO_STR(Thread::current()->is_VM_thread()) 328 329 #define assert_heap_locked() \ 330 do { \ 331 assert(Heap_lock->owned_by_self(), \ 332 heap_locking_asserts_params("should be holding the Heap_lock")); \ 333 } while (0) 334 335 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 336 do { \ 337 assert(Heap_lock->owned_by_self() || \ 338 (SafepointSynchronize::is_at_safepoint() && \ 339 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 340 heap_locking_asserts_params("should be holding the Heap_lock or " \ 341 "should be at a safepoint")); \ 342 } while (0) 343 344 #define assert_heap_locked_and_not_at_safepoint() \ 345 do { \ 346 assert(Heap_lock->owned_by_self() && \ 347 !SafepointSynchronize::is_at_safepoint(), \ 348 heap_locking_asserts_params("should be holding the Heap_lock and " \ 349 "should not be at a safepoint")); \ 350 } while (0) 351 352 #define assert_heap_not_locked() \ 353 do { \ 354 assert(!Heap_lock->owned_by_self(), \ 355 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 356 } while (0) 357 358 #define assert_heap_not_locked_and_not_at_safepoint() \ 359 do { \ 360 assert(!Heap_lock->owned_by_self() && \ 361 !SafepointSynchronize::is_at_safepoint(), \ 362 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 363 "should not be at a safepoint")); \ 364 } while (0) 365 366 #define assert_at_safepoint(_should_be_vm_thread_) \ 367 do { \ 368 assert(SafepointSynchronize::is_at_safepoint() && \ 369 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 370 heap_locking_asserts_params("should be at a safepoint")); \ 371 } while (0) 372 373 #define assert_not_at_safepoint() \ 374 do { \ 375 assert(!SafepointSynchronize::is_at_safepoint(), \ 376 heap_locking_asserts_params("should not be at a safepoint")); \ 377 } while (0) 378 379 protected: 380 381 // The young region list. 382 G1EdenRegions _eden; 383 G1SurvivorRegions _survivor; 384 385 STWGCTimer* _gc_timer_stw; 386 387 G1NewTracer* _gc_tracer_stw; 388 389 // The current policy object for the collector. 390 G1Policy* _g1_policy; 391 G1HeapSizingPolicy* _heap_sizing_policy; 392 393 G1CollectionSet _collection_set; 394 395 // This is the second level of trying to allocate a new region. If 396 // new_region() didn't find a region on the free_list, this call will 397 // check whether there's anything available on the 398 // secondary_free_list and/or wait for more regions to appear on 399 // that list, if _free_regions_coming is set. 400 HeapRegion* new_region_try_secondary_free_list(bool is_old); 401 402 // Try to allocate a single non-humongous HeapRegion sufficient for 403 // an allocation of the given word_size. If do_expand is true, 404 // attempt to expand the heap if necessary to satisfy the allocation 405 // request. If the region is to be used as an old region or for a 406 // humongous object, set is_old to true. If not, to false. 407 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 408 409 // Initialize a contiguous set of free regions of length num_regions 410 // and starting at index first so that they appear as a single 411 // humongous region. 412 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 413 uint num_regions, 414 size_t word_size, 415 AllocationContext_t context); 416 417 // Attempt to allocate a humongous object of the given size. Return 418 // NULL if unsuccessful. 419 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 420 421 // The following two methods, allocate_new_tlab() and 422 // mem_allocate(), are the two main entry points from the runtime 423 // into the G1's allocation routines. They have the following 424 // assumptions: 425 // 426 // * They should both be called outside safepoints. 427 // 428 // * They should both be called without holding the Heap_lock. 429 // 430 // * All allocation requests for new TLABs should go to 431 // allocate_new_tlab(). 432 // 433 // * All non-TLAB allocation requests should go to mem_allocate(). 434 // 435 // * If either call cannot satisfy the allocation request using the 436 // current allocating region, they will try to get a new one. If 437 // this fails, they will attempt to do an evacuation pause and 438 // retry the allocation. 439 // 440 // * If all allocation attempts fail, even after trying to schedule 441 // an evacuation pause, allocate_new_tlab() will return NULL, 442 // whereas mem_allocate() will attempt a heap expansion and/or 443 // schedule a Full GC. 444 // 445 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 446 // should never be called with word_size being humongous. All 447 // humongous allocation requests should go to mem_allocate() which 448 // will satisfy them with a special path. 449 450 virtual HeapWord* allocate_new_tlab(size_t word_size); 451 452 virtual HeapWord* mem_allocate(size_t word_size, 453 bool* gc_overhead_limit_was_exceeded); 454 455 // First-level mutator allocation attempt: try to allocate out of 456 // the mutator alloc region without taking the Heap_lock. This 457 // should only be used for non-humongous allocations. 458 inline HeapWord* attempt_allocation(size_t word_size); 459 460 // Second-level mutator allocation attempt: take the Heap_lock and 461 // retry the allocation attempt, potentially scheduling a GC 462 // pause. This should only be used for non-humongous allocations. 463 HeapWord* attempt_allocation_slow(size_t word_size, 464 AllocationContext_t context); 465 466 // Takes the Heap_lock and attempts a humongous allocation. It can 467 // potentially schedule a GC pause. 468 HeapWord* attempt_allocation_humongous(size_t word_size); 469 470 // Allocation attempt that should be called during safepoints (e.g., 471 // at the end of a successful GC). expect_null_mutator_alloc_region 472 // specifies whether the mutator alloc region is expected to be NULL 473 // or not. 474 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 475 AllocationContext_t context, 476 bool expect_null_mutator_alloc_region); 477 478 // These methods are the "callbacks" from the G1AllocRegion class. 479 480 // For mutator alloc regions. 481 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 482 void retire_mutator_alloc_region(HeapRegion* alloc_region, 483 size_t allocated_bytes); 484 485 // For GC alloc regions. 486 bool has_more_regions(InCSetState dest); 487 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest); 488 void retire_gc_alloc_region(HeapRegion* alloc_region, 489 size_t allocated_bytes, InCSetState dest); 490 491 // - if explicit_gc is true, the GC is for a System.gc() etc, 492 // otherwise it's for a failed allocation. 493 // - if clear_all_soft_refs is true, all soft references should be 494 // cleared during the GC. 495 // - it returns false if it is unable to do the collection due to the 496 // GC locker being active, true otherwise. 497 bool do_full_collection(bool explicit_gc, 498 bool clear_all_soft_refs); 499 500 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 501 virtual void do_full_collection(bool clear_all_soft_refs); 502 503 // Resize the heap if necessary after a full collection. 504 void resize_if_necessary_after_full_collection(); 505 506 // Callback from VM_G1CollectForAllocation operation. 507 // This function does everything necessary/possible to satisfy a 508 // failed allocation request (including collection, expansion, etc.) 509 HeapWord* satisfy_failed_allocation(size_t word_size, 510 AllocationContext_t context, 511 bool* succeeded); 512 private: 513 // Internal helpers used during full GC to split it up to 514 // increase readability. 515 void abort_concurrent_cycle(); 516 void verify_before_full_collection(bool explicit_gc); 517 void prepare_heap_for_full_collection(); 518 void prepare_heap_for_mutators(); 519 void abort_refinement(); 520 void verify_after_full_collection(); 521 void print_heap_after_full_collection(G1HeapTransition* heap_transition); 522 523 // Helper method for satisfy_failed_allocation() 524 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 525 AllocationContext_t context, 526 bool do_gc, 527 bool clear_all_soft_refs, 528 bool expect_null_mutator_alloc_region, 529 bool* gc_succeeded); 530 531 protected: 532 // Attempting to expand the heap sufficiently 533 // to support an allocation of the given "word_size". If 534 // successful, perform the allocation and return the address of the 535 // allocated block, or else "NULL". 536 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 537 538 // Preserve any referents discovered by concurrent marking that have not yet been 539 // copied by the STW pause. 540 void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states); 541 // Process any reference objects discovered during 542 // an incremental evacuation pause. 543 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 544 545 // Enqueue any remaining discovered references 546 // after processing. 547 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states); 548 549 // Merges the information gathered on a per-thread basis for all worker threads 550 // during GC into global variables. 551 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states); 552 public: 553 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; } 554 555 WorkGang* workers() const { return _workers; } 556 557 G1Allocator* allocator() { 558 return _allocator; 559 } 560 561 G1HeapVerifier* verifier() { 562 return _verifier; 563 } 564 565 G1MonitoringSupport* g1mm() { 566 assert(_g1mm != NULL, "should have been initialized"); 567 return _g1mm; 568 } 569 570 // Expand the garbage-first heap by at least the given size (in bytes!). 571 // Returns true if the heap was expanded by the requested amount; 572 // false otherwise. 573 // (Rounds up to a HeapRegion boundary.) 574 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL); 575 576 // Returns the PLAB statistics for a given destination. 577 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 578 579 // Determines PLAB size for a given destination. 580 inline size_t desired_plab_sz(InCSetState dest); 581 582 // Do anything common to GC's. 583 void gc_prologue(bool full); 584 void gc_epilogue(bool full); 585 586 // Modify the reclaim candidate set and test for presence. 587 // These are only valid for starts_humongous regions. 588 inline void set_humongous_reclaim_candidate(uint region, bool value); 589 inline bool is_humongous_reclaim_candidate(uint region); 590 591 // Remove from the reclaim candidate set. Also remove from the 592 // collection set so that later encounters avoid the slow path. 593 inline void set_humongous_is_live(oop obj); 594 595 // Register the given region to be part of the collection set. 596 inline void register_humongous_region_with_cset(uint index); 597 // Register regions with humongous objects (actually on the start region) in 598 // the in_cset_fast_test table. 599 void register_humongous_regions_with_cset(); 600 // We register a region with the fast "in collection set" test. We 601 // simply set to true the array slot corresponding to this region. 602 void register_young_region_with_cset(HeapRegion* r) { 603 _in_cset_fast_test.set_in_young(r->hrm_index()); 604 } 605 void register_old_region_with_cset(HeapRegion* r) { 606 _in_cset_fast_test.set_in_old(r->hrm_index()); 607 } 608 inline void register_ext_region_with_cset(HeapRegion* r) { 609 _in_cset_fast_test.set_ext(r->hrm_index()); 610 } 611 void clear_in_cset(const HeapRegion* hr) { 612 _in_cset_fast_test.clear(hr); 613 } 614 615 void clear_cset_fast_test() { 616 _in_cset_fast_test.clear(); 617 } 618 619 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 620 621 // This is called at the start of either a concurrent cycle or a Full 622 // GC to update the number of old marking cycles started. 623 void increment_old_marking_cycles_started(); 624 625 // This is called at the end of either a concurrent cycle or a Full 626 // GC to update the number of old marking cycles completed. Those two 627 // can happen in a nested fashion, i.e., we start a concurrent 628 // cycle, a Full GC happens half-way through it which ends first, 629 // and then the cycle notices that a Full GC happened and ends 630 // too. The concurrent parameter is a boolean to help us do a bit 631 // tighter consistency checking in the method. If concurrent is 632 // false, the caller is the inner caller in the nesting (i.e., the 633 // Full GC). If concurrent is true, the caller is the outer caller 634 // in this nesting (i.e., the concurrent cycle). Further nesting is 635 // not currently supported. The end of this call also notifies 636 // the FullGCCount_lock in case a Java thread is waiting for a full 637 // GC to happen (e.g., it called System.gc() with 638 // +ExplicitGCInvokesConcurrent). 639 void increment_old_marking_cycles_completed(bool concurrent); 640 641 uint old_marking_cycles_completed() { 642 return _old_marking_cycles_completed; 643 } 644 645 G1HRPrinter* hr_printer() { return &_hr_printer; } 646 647 // Allocates a new heap region instance. 648 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 649 650 // Allocate the highest free region in the reserved heap. This will commit 651 // regions as necessary. 652 HeapRegion* alloc_highest_free_region(); 653 654 // Frees a non-humongous region by initializing its contents and 655 // adding it to the free list that's passed as a parameter (this is 656 // usually a local list which will be appended to the master free 657 // list later). The used bytes of freed regions are accumulated in 658 // pre_used. If skip_remset is true, the region's RSet will not be freed 659 // up. If skip_hot_card_cache is true, the region's hot card cache will not 660 // be freed up. The assumption is that this will be done later. 661 // The locked parameter indicates if the caller has already taken 662 // care of proper synchronization. This may allow some optimizations. 663 void free_region(HeapRegion* hr, 664 FreeRegionList* free_list, 665 bool skip_remset, 666 bool skip_hot_card_cache = false, 667 bool locked = false); 668 669 // It dirties the cards that cover the block so that the post 670 // write barrier never queues anything when updating objects on this 671 // block. It is assumed (and in fact we assert) that the block 672 // belongs to a young region. 673 inline void dirty_young_block(HeapWord* start, size_t word_size); 674 675 // Frees a humongous region by collapsing it into individual regions 676 // and calling free_region() for each of them. The freed regions 677 // will be added to the free list that's passed as a parameter (this 678 // is usually a local list which will be appended to the master free 679 // list later). The used bytes of freed regions are accumulated in 680 // pre_used. If skip_remset is true, the region's RSet will not be freed 681 // up. The assumption is that this will be done later. 682 void free_humongous_region(HeapRegion* hr, 683 FreeRegionList* free_list, 684 bool skip_remset); 685 686 // Facility for allocating in 'archive' regions in high heap memory and 687 // recording the allocated ranges. These should all be called from the 688 // VM thread at safepoints, without the heap lock held. They can be used 689 // to create and archive a set of heap regions which can be mapped at the 690 // same fixed addresses in a subsequent JVM invocation. 691 void begin_archive_alloc_range(bool open = false); 692 693 // Check if the requested size would be too large for an archive allocation. 694 bool is_archive_alloc_too_large(size_t word_size); 695 696 // Allocate memory of the requested size from the archive region. This will 697 // return NULL if the size is too large or if no memory is available. It 698 // does not trigger a garbage collection. 699 HeapWord* archive_mem_allocate(size_t word_size); 700 701 // Optionally aligns the end address and returns the allocated ranges in 702 // an array of MemRegions in order of ascending addresses. 703 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 704 size_t end_alignment_in_bytes = 0); 705 706 // Facility for allocating a fixed range within the heap and marking 707 // the containing regions as 'archive'. For use at JVM init time, when the 708 // caller may mmap archived heap data at the specified range(s). 709 // Verify that the MemRegions specified in the argument array are within the 710 // reserved heap. 711 bool check_archive_addresses(MemRegion* range, size_t count); 712 713 // Commit the appropriate G1 regions containing the specified MemRegions 714 // and mark them as 'archive' regions. The regions in the array must be 715 // non-overlapping and in order of ascending address. 716 bool alloc_archive_regions(MemRegion* range, size_t count, bool open); 717 718 // Insert any required filler objects in the G1 regions around the specified 719 // ranges to make the regions parseable. This must be called after 720 // alloc_archive_regions, and after class loading has occurred. 721 void fill_archive_regions(MemRegion* range, size_t count); 722 723 // For each of the specified MemRegions, uncommit the containing G1 regions 724 // which had been allocated by alloc_archive_regions. This should be called 725 // rather than fill_archive_regions at JVM init time if the archive file 726 // mapping failed, with the same non-overlapping and sorted MemRegion array. 727 void dealloc_archive_regions(MemRegion* range, size_t count); 728 729 protected: 730 731 // Shrink the garbage-first heap by at most the given size (in bytes!). 732 // (Rounds down to a HeapRegion boundary.) 733 virtual void shrink(size_t expand_bytes); 734 void shrink_helper(size_t expand_bytes); 735 736 #if TASKQUEUE_STATS 737 static void print_taskqueue_stats_hdr(outputStream* const st); 738 void print_taskqueue_stats() const; 739 void reset_taskqueue_stats(); 740 #endif // TASKQUEUE_STATS 741 742 // Schedule the VM operation that will do an evacuation pause to 743 // satisfy an allocation request of word_size. *succeeded will 744 // return whether the VM operation was successful (it did do an 745 // evacuation pause) or not (another thread beat us to it or the GC 746 // locker was active). Given that we should not be holding the 747 // Heap_lock when we enter this method, we will pass the 748 // gc_count_before (i.e., total_collections()) as a parameter since 749 // it has to be read while holding the Heap_lock. Currently, both 750 // methods that call do_collection_pause() release the Heap_lock 751 // before the call, so it's easy to read gc_count_before just before. 752 HeapWord* do_collection_pause(size_t word_size, 753 uint gc_count_before, 754 bool* succeeded, 755 GCCause::Cause gc_cause); 756 757 void wait_for_root_region_scanning(); 758 759 // The guts of the incremental collection pause, executed by the vm 760 // thread. It returns false if it is unable to do the collection due 761 // to the GC locker being active, true otherwise 762 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 763 764 // Actually do the work of evacuating the collection set. 765 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states); 766 767 void pre_evacuate_collection_set(); 768 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 769 770 // Print the header for the per-thread termination statistics. 771 static void print_termination_stats_hdr(); 772 // Print actual per-thread termination statistics. 773 void print_termination_stats(uint worker_id, 774 double elapsed_ms, 775 double strong_roots_ms, 776 double term_ms, 777 size_t term_attempts, 778 size_t alloc_buffer_waste, 779 size_t undo_waste) const; 780 // Update object copying statistics. 781 void record_obj_copy_mem_stats(); 782 783 // The hot card cache for remembered set insertion optimization. 784 G1HotCardCache* _hot_card_cache; 785 786 // The g1 remembered set of the heap. 787 G1RemSet* _g1_rem_set; 788 789 // A set of cards that cover the objects for which the Rsets should be updated 790 // concurrently after the collection. 791 DirtyCardQueueSet _dirty_card_queue_set; 792 793 // After a collection pause, convert the regions in the collection set into free 794 // regions. 795 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 796 797 // Abandon the current collection set without recording policy 798 // statistics or updating free lists. 799 void abandon_collection_set(G1CollectionSet* collection_set); 800 801 // The concurrent marker (and the thread it runs in.) 802 G1ConcurrentMark* _cm; 803 ConcurrentMarkThread* _cmThread; 804 805 // The concurrent refiner. 806 G1ConcurrentRefine* _cr; 807 808 // The parallel task queues 809 RefToScanQueueSet *_task_queues; 810 811 // True iff a evacuation has failed in the current collection. 812 bool _evacuation_failed; 813 814 EvacuationFailedInfo* _evacuation_failed_info_array; 815 816 // Failed evacuations cause some logical from-space objects to have 817 // forwarding pointers to themselves. Reset them. 818 void remove_self_forwarding_pointers(); 819 820 // Restore the objects in the regions in the collection set after an 821 // evacuation failure. 822 void restore_after_evac_failure(); 823 824 PreservedMarksSet _preserved_marks_set; 825 826 // Preserve the mark of "obj", if necessary, in preparation for its mark 827 // word being overwritten with a self-forwarding-pointer. 828 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 829 830 #ifndef PRODUCT 831 // Support for forcing evacuation failures. Analogous to 832 // PromotionFailureALot for the other collectors. 833 834 // Records whether G1EvacuationFailureALot should be in effect 835 // for the current GC 836 bool _evacuation_failure_alot_for_current_gc; 837 838 // Used to record the GC number for interval checking when 839 // determining whether G1EvaucationFailureALot is in effect 840 // for the current GC. 841 size_t _evacuation_failure_alot_gc_number; 842 843 // Count of the number of evacuations between failures. 844 volatile size_t _evacuation_failure_alot_count; 845 846 // Set whether G1EvacuationFailureALot should be in effect 847 // for the current GC (based upon the type of GC and which 848 // command line flags are set); 849 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 850 bool during_initial_mark, 851 bool during_marking); 852 853 inline void set_evacuation_failure_alot_for_current_gc(); 854 855 // Return true if it's time to cause an evacuation failure. 856 inline bool evacuation_should_fail(); 857 858 // Reset the G1EvacuationFailureALot counters. Should be called at 859 // the end of an evacuation pause in which an evacuation failure occurred. 860 inline void reset_evacuation_should_fail(); 861 #endif // !PRODUCT 862 863 // ("Weak") Reference processing support. 864 // 865 // G1 has 2 instances of the reference processor class. One 866 // (_ref_processor_cm) handles reference object discovery 867 // and subsequent processing during concurrent marking cycles. 868 // 869 // The other (_ref_processor_stw) handles reference object 870 // discovery and processing during full GCs and incremental 871 // evacuation pauses. 872 // 873 // During an incremental pause, reference discovery will be 874 // temporarily disabled for _ref_processor_cm and will be 875 // enabled for _ref_processor_stw. At the end of the evacuation 876 // pause references discovered by _ref_processor_stw will be 877 // processed and discovery will be disabled. The previous 878 // setting for reference object discovery for _ref_processor_cm 879 // will be re-instated. 880 // 881 // At the start of marking: 882 // * Discovery by the CM ref processor is verified to be inactive 883 // and it's discovered lists are empty. 884 // * Discovery by the CM ref processor is then enabled. 885 // 886 // At the end of marking: 887 // * Any references on the CM ref processor's discovered 888 // lists are processed (possibly MT). 889 // 890 // At the start of full GC we: 891 // * Disable discovery by the CM ref processor and 892 // empty CM ref processor's discovered lists 893 // (without processing any entries). 894 // * Verify that the STW ref processor is inactive and it's 895 // discovered lists are empty. 896 // * Temporarily set STW ref processor discovery as single threaded. 897 // * Temporarily clear the STW ref processor's _is_alive_non_header 898 // field. 899 // * Finally enable discovery by the STW ref processor. 900 // 901 // The STW ref processor is used to record any discovered 902 // references during the full GC. 903 // 904 // At the end of a full GC we: 905 // * Enqueue any reference objects discovered by the STW ref processor 906 // that have non-live referents. This has the side-effect of 907 // making the STW ref processor inactive by disabling discovery. 908 // * Verify that the CM ref processor is still inactive 909 // and no references have been placed on it's discovered 910 // lists (also checked as a precondition during initial marking). 911 912 // The (stw) reference processor... 913 ReferenceProcessor* _ref_processor_stw; 914 915 // During reference object discovery, the _is_alive_non_header 916 // closure (if non-null) is applied to the referent object to 917 // determine whether the referent is live. If so then the 918 // reference object does not need to be 'discovered' and can 919 // be treated as a regular oop. This has the benefit of reducing 920 // the number of 'discovered' reference objects that need to 921 // be processed. 922 // 923 // Instance of the is_alive closure for embedding into the 924 // STW reference processor as the _is_alive_non_header field. 925 // Supplying a value for the _is_alive_non_header field is 926 // optional but doing so prevents unnecessary additions to 927 // the discovered lists during reference discovery. 928 G1STWIsAliveClosure _is_alive_closure_stw; 929 930 // The (concurrent marking) reference processor... 931 ReferenceProcessor* _ref_processor_cm; 932 933 // Instance of the concurrent mark is_alive closure for embedding 934 // into the Concurrent Marking reference processor as the 935 // _is_alive_non_header field. Supplying a value for the 936 // _is_alive_non_header field is optional but doing so prevents 937 // unnecessary additions to the discovered lists during reference 938 // discovery. 939 G1CMIsAliveClosure _is_alive_closure_cm; 940 941 volatile bool _free_regions_coming; 942 943 public: 944 945 RefToScanQueue *task_queue(uint i) const; 946 947 uint num_task_queues() const; 948 949 // A set of cards where updates happened during the GC 950 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 951 952 // Create a G1CollectedHeap with the specified policy. 953 // Must call the initialize method afterwards. 954 // May not return if something goes wrong. 955 G1CollectedHeap(G1CollectorPolicy* policy); 956 957 private: 958 jint initialize_concurrent_refinement(); 959 jint initialize_young_gen_sampling_thread(); 960 public: 961 // Initialize the G1CollectedHeap to have the initial and 962 // maximum sizes and remembered and barrier sets 963 // specified by the policy object. 964 jint initialize(); 965 966 virtual void stop(); 967 virtual void safepoint_synchronize_begin(); 968 virtual void safepoint_synchronize_end(); 969 970 // Return the (conservative) maximum heap alignment for any G1 heap 971 static size_t conservative_max_heap_alignment(); 972 973 // Does operations required after initialization has been done. 974 void post_initialize(); 975 976 // Initialize weak reference processing. 977 void ref_processing_init(); 978 979 virtual Name kind() const { 980 return CollectedHeap::G1CollectedHeap; 981 } 982 983 virtual const char* name() const { 984 return "G1"; 985 } 986 987 const G1CollectorState* collector_state() const { return &_collector_state; } 988 G1CollectorState* collector_state() { return &_collector_state; } 989 990 // The current policy object for the collector. 991 G1Policy* g1_policy() const { return _g1_policy; } 992 993 const G1CollectionSet* collection_set() const { return &_collection_set; } 994 G1CollectionSet* collection_set() { return &_collection_set; } 995 996 virtual CollectorPolicy* collector_policy() const; 997 998 virtual SoftRefPolicy* soft_ref_policy(); 999 1000 virtual GrowableArray<GCMemoryManager*> memory_managers(); 1001 virtual GrowableArray<MemoryPool*> memory_pools(); 1002 1003 // The rem set and barrier set. 1004 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1005 1006 // Try to minimize the remembered set. 1007 void scrub_rem_set(); 1008 1009 uint get_gc_time_stamp() { 1010 return _gc_time_stamp; 1011 } 1012 1013 inline void reset_gc_time_stamp(); 1014 1015 void check_gc_time_stamps() PRODUCT_RETURN; 1016 1017 inline void increment_gc_time_stamp(); 1018 1019 // Reset the given region's GC timestamp. If it's starts humongous, 1020 // also reset the GC timestamp of its corresponding 1021 // continues humongous regions too. 1022 void reset_gc_time_stamps(HeapRegion* hr); 1023 1024 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 1025 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i); 1026 1027 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. 1028 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i); 1029 1030 // The shared block offset table array. 1031 G1BlockOffsetTable* bot() const { return _bot; } 1032 1033 // Reference Processing accessors 1034 1035 // The STW reference processor.... 1036 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1037 1038 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1039 1040 // The Concurrent Marking reference processor... 1041 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1042 1043 size_t unused_committed_regions_in_bytes() const; 1044 virtual size_t capacity() const; 1045 virtual size_t used() const; 1046 // This should be called when we're not holding the heap lock. The 1047 // result might be a bit inaccurate. 1048 size_t used_unlocked() const; 1049 size_t recalculate_used() const; 1050 1051 // These virtual functions do the actual allocation. 1052 // Some heaps may offer a contiguous region for shared non-blocking 1053 // allocation, via inlined code (by exporting the address of the top and 1054 // end fields defining the extent of the contiguous allocation region.) 1055 // But G1CollectedHeap doesn't yet support this. 1056 1057 virtual bool is_maximal_no_gc() const { 1058 return _hrm.available() == 0; 1059 } 1060 1061 // Returns whether there are any regions left in the heap for allocation. 1062 bool has_regions_left_for_allocation() const { 1063 return !is_maximal_no_gc() || num_free_regions() != 0; 1064 } 1065 1066 // The current number of regions in the heap. 1067 uint num_regions() const { return _hrm.length(); } 1068 1069 // The max number of regions in the heap. 1070 uint max_regions() const { return _hrm.max_length(); } 1071 1072 // The number of regions that are completely free. 1073 uint num_free_regions() const { return _hrm.num_free_regions(); } 1074 1075 MemoryUsage get_auxiliary_data_memory_usage() const { 1076 return _hrm.get_auxiliary_data_memory_usage(); 1077 } 1078 1079 // The number of regions that are not completely free. 1080 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1081 1082 #ifdef ASSERT 1083 bool is_on_master_free_list(HeapRegion* hr) { 1084 return _hrm.is_free(hr); 1085 } 1086 #endif // ASSERT 1087 1088 // Wrapper for the region list operations that can be called from 1089 // methods outside this class. 1090 1091 void secondary_free_list_add(FreeRegionList* list) { 1092 _secondary_free_list.add_ordered(list); 1093 } 1094 1095 void append_secondary_free_list() { 1096 _hrm.insert_list_into_free_list(&_secondary_free_list); 1097 } 1098 1099 void append_secondary_free_list_if_not_empty_with_lock() { 1100 // If the secondary free list looks empty there's no reason to 1101 // take the lock and then try to append it. 1102 if (!_secondary_free_list.is_empty()) { 1103 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1104 append_secondary_free_list(); 1105 } 1106 } 1107 1108 inline void old_set_add(HeapRegion* hr); 1109 inline void old_set_remove(HeapRegion* hr); 1110 1111 size_t non_young_capacity_bytes() { 1112 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes; 1113 } 1114 1115 void set_free_regions_coming(); 1116 void reset_free_regions_coming(); 1117 bool free_regions_coming() { return _free_regions_coming; } 1118 void wait_while_free_regions_coming(); 1119 1120 // Determine whether the given region is one that we are using as an 1121 // old GC alloc region. 1122 bool is_old_gc_alloc_region(HeapRegion* hr); 1123 1124 // Perform a collection of the heap; intended for use in implementing 1125 // "System.gc". This probably implies as full a collection as the 1126 // "CollectedHeap" supports. 1127 virtual void collect(GCCause::Cause cause); 1128 1129 // True iff an evacuation has failed in the most-recent collection. 1130 bool evacuation_failed() { return _evacuation_failed; } 1131 1132 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed); 1133 void prepend_to_freelist(FreeRegionList* list); 1134 void decrement_summary_bytes(size_t bytes); 1135 1136 virtual bool is_in(const void* p) const; 1137 #ifdef ASSERT 1138 // Returns whether p is in one of the available areas of the heap. Slow but 1139 // extensive version. 1140 bool is_in_exact(const void* p) const; 1141 #endif 1142 1143 // Return "TRUE" iff the given object address is within the collection 1144 // set. Assumes that the reference points into the heap. 1145 inline bool is_in_cset(const HeapRegion *hr); 1146 inline bool is_in_cset(oop obj); 1147 inline bool is_in_cset(HeapWord* addr); 1148 1149 inline bool is_in_cset_or_humongous(const oop obj); 1150 1151 private: 1152 // This array is used for a quick test on whether a reference points into 1153 // the collection set or not. Each of the array's elements denotes whether the 1154 // corresponding region is in the collection set or not. 1155 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1156 1157 public: 1158 1159 inline InCSetState in_cset_state(const oop obj); 1160 1161 // Return "TRUE" iff the given object address is in the reserved 1162 // region of g1. 1163 bool is_in_g1_reserved(const void* p) const { 1164 return _hrm.reserved().contains(p); 1165 } 1166 1167 // Returns a MemRegion that corresponds to the space that has been 1168 // reserved for the heap 1169 MemRegion g1_reserved() const { 1170 return _hrm.reserved(); 1171 } 1172 1173 virtual bool is_in_closed_subset(const void* p) const; 1174 1175 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1176 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set()); 1177 } 1178 1179 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; } 1180 1181 // Iteration functions. 1182 1183 // Iterate over all objects, calling "cl.do_object" on each. 1184 virtual void object_iterate(ObjectClosure* cl); 1185 1186 virtual void safe_object_iterate(ObjectClosure* cl) { 1187 object_iterate(cl); 1188 } 1189 1190 // Iterate over heap regions, in address order, terminating the 1191 // iteration early if the "do_heap_region" method returns "true". 1192 void heap_region_iterate(HeapRegionClosure* blk) const; 1193 1194 // Return the region with the given index. It assumes the index is valid. 1195 inline HeapRegion* region_at(uint index) const; 1196 1197 // Return the next region (by index) that is part of the same 1198 // humongous object that hr is part of. 1199 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1200 1201 // Calculate the region index of the given address. Given address must be 1202 // within the heap. 1203 inline uint addr_to_region(HeapWord* addr) const; 1204 1205 inline HeapWord* bottom_addr_for_region(uint index) const; 1206 1207 // Two functions to iterate over the heap regions in parallel. Threads 1208 // compete using the HeapRegionClaimer to claim the regions before 1209 // applying the closure on them. 1210 // The _from_worker_offset version uses the HeapRegionClaimer and 1211 // the worker id to calculate a start offset to prevent all workers to 1212 // start from the point. 1213 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 1214 HeapRegionClaimer* hrclaimer, 1215 uint worker_id) const; 1216 1217 void heap_region_par_iterate_from_start(HeapRegionClosure* cl, 1218 HeapRegionClaimer* hrclaimer) const; 1219 1220 // Iterate over the regions (if any) in the current collection set. 1221 void collection_set_iterate(HeapRegionClosure* blk); 1222 1223 // Iterate over the regions (if any) in the current collection set. Starts the 1224 // iteration over the entire collection set so that the start regions of a given 1225 // worker id over the set active_workers are evenly spread across the set of 1226 // collection set regions. 1227 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id); 1228 1229 // Returns the HeapRegion that contains addr. addr must not be NULL. 1230 template <class T> 1231 inline HeapRegion* heap_region_containing(const T addr) const; 1232 1233 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1234 // each address in the (reserved) heap is a member of exactly 1235 // one block. The defining characteristic of a block is that it is 1236 // possible to find its size, and thus to progress forward to the next 1237 // block. (Blocks may be of different sizes.) Thus, blocks may 1238 // represent Java objects, or they might be free blocks in a 1239 // free-list-based heap (or subheap), as long as the two kinds are 1240 // distinguishable and the size of each is determinable. 1241 1242 // Returns the address of the start of the "block" that contains the 1243 // address "addr". We say "blocks" instead of "object" since some heaps 1244 // may not pack objects densely; a chunk may either be an object or a 1245 // non-object. 1246 virtual HeapWord* block_start(const void* addr) const; 1247 1248 // Requires "addr" to be the start of a chunk, and returns its size. 1249 // "addr + size" is required to be the start of a new chunk, or the end 1250 // of the active area of the heap. 1251 virtual size_t block_size(const HeapWord* addr) const; 1252 1253 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1254 // the block is an object. 1255 virtual bool block_is_obj(const HeapWord* addr) const; 1256 1257 // Section on thread-local allocation buffers (TLABs) 1258 // See CollectedHeap for semantics. 1259 1260 bool supports_tlab_allocation() const; 1261 size_t tlab_capacity(Thread* ignored) const; 1262 size_t tlab_used(Thread* ignored) const; 1263 size_t max_tlab_size() const; 1264 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1265 1266 inline bool is_in_young(const oop obj); 1267 1268 // Returns "true" iff the given word_size is "very large". 1269 static bool is_humongous(size_t word_size) { 1270 // Note this has to be strictly greater-than as the TLABs 1271 // are capped at the humongous threshold and we want to 1272 // ensure that we don't try to allocate a TLAB as 1273 // humongous and that we don't allocate a humongous 1274 // object in a TLAB. 1275 return word_size > _humongous_object_threshold_in_words; 1276 } 1277 1278 // Returns the humongous threshold for a specific region size 1279 static size_t humongous_threshold_for(size_t region_size) { 1280 return (region_size / 2); 1281 } 1282 1283 // Returns the number of regions the humongous object of the given word size 1284 // requires. 1285 static size_t humongous_obj_size_in_regions(size_t word_size); 1286 1287 // Print the maximum heap capacity. 1288 virtual size_t max_capacity() const; 1289 1290 virtual jlong millis_since_last_gc(); 1291 1292 1293 // Convenience function to be used in situations where the heap type can be 1294 // asserted to be this type. 1295 static G1CollectedHeap* heap(); 1296 1297 void set_region_short_lived_locked(HeapRegion* hr); 1298 // add appropriate methods for any other surv rate groups 1299 1300 const G1SurvivorRegions* survivor() const { return &_survivor; } 1301 1302 uint survivor_regions_count() const { 1303 return _survivor.length(); 1304 } 1305 1306 uint eden_regions_count() const { 1307 return _eden.length(); 1308 } 1309 1310 uint young_regions_count() const { 1311 return _eden.length() + _survivor.length(); 1312 } 1313 1314 uint old_regions_count() const { return _old_set.length(); } 1315 1316 uint humongous_regions_count() const { return _humongous_set.length(); } 1317 1318 #ifdef ASSERT 1319 bool check_young_list_empty(); 1320 #endif 1321 1322 // *** Stuff related to concurrent marking. It's not clear to me that so 1323 // many of these need to be public. 1324 1325 // The functions below are helper functions that a subclass of 1326 // "CollectedHeap" can use in the implementation of its virtual 1327 // functions. 1328 // This performs a concurrent marking of the live objects in a 1329 // bitmap off to the side. 1330 void doConcurrentMark(); 1331 1332 bool isMarkedNext(oop obj) const; 1333 1334 // Determine if an object is dead, given the object and also 1335 // the region to which the object belongs. An object is dead 1336 // iff a) it was not allocated since the last mark, b) it 1337 // is not marked, and c) it is not in an archive region. 1338 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1339 return 1340 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) && 1341 !hr->is_archive(); 1342 } 1343 1344 // This function returns true when an object has been 1345 // around since the previous marking and hasn't yet 1346 // been marked during this marking, and is not in an archive region. 1347 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1348 return 1349 !hr->obj_allocated_since_next_marking(obj) && 1350 !isMarkedNext(obj) && 1351 !hr->is_archive(); 1352 } 1353 1354 // Determine if an object is dead, given only the object itself. 1355 // This will find the region to which the object belongs and 1356 // then call the region version of the same function. 1357 1358 // Added if it is NULL it isn't dead. 1359 1360 inline bool is_obj_dead(const oop obj) const; 1361 1362 inline bool is_obj_ill(const oop obj) const; 1363 1364 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const; 1365 inline bool is_obj_dead_full(const oop obj) const; 1366 1367 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1368 1369 // Refinement 1370 1371 G1ConcurrentRefine* concurrent_refine() const { return _cr; } 1372 1373 // Optimized nmethod scanning support routines 1374 1375 // Is an oop scavengeable 1376 virtual bool is_scavengable(oop obj); 1377 1378 // Register the given nmethod with the G1 heap. 1379 virtual void register_nmethod(nmethod* nm); 1380 1381 // Unregister the given nmethod from the G1 heap. 1382 virtual void unregister_nmethod(nmethod* nm); 1383 1384 // Free up superfluous code root memory. 1385 void purge_code_root_memory(); 1386 1387 // Rebuild the strong code root lists for each region 1388 // after a full GC. 1389 void rebuild_strong_code_roots(); 1390 1391 // Partial cleaning used when class unloading is disabled. 1392 // Let the caller choose what structures to clean out: 1393 // - StringTable 1394 // - SymbolTable 1395 // - StringDeduplication structures 1396 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup); 1397 1398 // Complete cleaning used when class unloading is enabled. 1399 // Cleans out all structures handled by partial_cleaning and also the CodeCache. 1400 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); 1401 1402 // Redirty logged cards in the refinement queue. 1403 void redirty_logged_cards(); 1404 // Verification 1405 1406 // Perform any cleanup actions necessary before allowing a verification. 1407 virtual void prepare_for_verify(); 1408 1409 // Perform verification. 1410 1411 // vo == UsePrevMarking -> use "prev" marking information, 1412 // vo == UseNextMarking -> use "next" marking information 1413 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS 1414 // 1415 // NOTE: Only the "prev" marking information is guaranteed to be 1416 // consistent most of the time, so most calls to this should use 1417 // vo == UsePrevMarking. 1418 // Currently, there is only one case where this is called with 1419 // vo == UseNextMarking, which is to verify the "next" marking 1420 // information at the end of remark. 1421 // Currently there is only one place where this is called with 1422 // vo == UseFullMarking, which is to verify the marking during a 1423 // full GC. 1424 void verify(VerifyOption vo); 1425 1426 // WhiteBox testing support. 1427 virtual bool supports_concurrent_phase_control() const; 1428 virtual const char* const* concurrent_phases() const; 1429 virtual bool request_concurrent_phase(const char* phase); 1430 1431 // The methods below are here for convenience and dispatch the 1432 // appropriate method depending on value of the given VerifyOption 1433 // parameter. The values for that parameter, and their meanings, 1434 // are the same as those above. 1435 1436 bool is_obj_dead_cond(const oop obj, 1437 const HeapRegion* hr, 1438 const VerifyOption vo) const; 1439 1440 bool is_obj_dead_cond(const oop obj, 1441 const VerifyOption vo) const; 1442 1443 G1HeapSummary create_g1_heap_summary(); 1444 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1445 1446 // Printing 1447 private: 1448 void print_heap_regions() const; 1449 void print_regions_on(outputStream* st) const; 1450 1451 public: 1452 virtual void print_on(outputStream* st) const; 1453 virtual void print_extended_on(outputStream* st) const; 1454 virtual void print_on_error(outputStream* st) const; 1455 1456 virtual void print_gc_threads_on(outputStream* st) const; 1457 virtual void gc_threads_do(ThreadClosure* tc) const; 1458 1459 // Override 1460 void print_tracing_info() const; 1461 1462 // The following two methods are helpful for debugging RSet issues. 1463 void print_cset_rsets() PRODUCT_RETURN; 1464 void print_all_rsets() PRODUCT_RETURN; 1465 1466 public: 1467 size_t pending_card_num(); 1468 1469 protected: 1470 size_t _max_heap_capacity; 1471 }; 1472 1473 class G1ParEvacuateFollowersClosure : public VoidClosure { 1474 private: 1475 double _start_term; 1476 double _term_time; 1477 size_t _term_attempts; 1478 1479 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 1480 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 1481 protected: 1482 G1CollectedHeap* _g1h; 1483 G1ParScanThreadState* _par_scan_state; 1484 RefToScanQueueSet* _queues; 1485 ParallelTaskTerminator* _terminator; 1486 1487 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 1488 RefToScanQueueSet* queues() { return _queues; } 1489 ParallelTaskTerminator* terminator() { return _terminator; } 1490 1491 public: 1492 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 1493 G1ParScanThreadState* par_scan_state, 1494 RefToScanQueueSet* queues, 1495 ParallelTaskTerminator* terminator) 1496 : _g1h(g1h), _par_scan_state(par_scan_state), 1497 _queues(queues), _terminator(terminator), 1498 _start_term(0.0), _term_time(0.0), _term_attempts(0) {} 1499 1500 void do_void(); 1501 1502 double term_time() const { return _term_time; } 1503 size_t term_attempts() const { return _term_attempts; } 1504 1505 private: 1506 inline bool offer_termination(); 1507 }; 1508 1509 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP