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 "memory/memRegion.hpp" 53 #include "services/memoryManager.hpp" 54 #include "utilities/stack.hpp" 55 56 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 57 // It uses the "Garbage First" heap organization and algorithm, which 58 // may combine concurrent marking with parallel, incremental compaction of 59 // heap subsets that will yield large amounts of garbage. 60 61 // Forward declarations 62 class HeapRegion; 63 class HRRSCleanupTask; 64 class GenerationSpec; 65 class G1ParScanThreadState; 66 class G1ParScanThreadStateSet; 67 class G1ParScanThreadState; 68 class MemoryPool; 69 class ObjectClosure; 70 class SpaceClosure; 71 class CompactibleSpaceClosure; 72 class Space; 73 class G1CollectionSet; 74 class G1CollectorPolicy; 75 class G1Policy; 76 class G1HotCardCache; 77 class G1RemSet; 78 class G1YoungRemSetSamplingThread; 79 class HeapRegionRemSetIterator; 80 class G1ConcurrentMark; 81 class ConcurrentMarkThread; 82 class G1ConcurrentRefine; 83 class GenerationCounters; 84 class STWGCTimer; 85 class G1NewTracer; 86 class EvacuationFailedInfo; 87 class nmethod; 88 class Ticks; 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* _g1; 111 public: 112 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 113 bool do_object_b(oop p); 114 }; 115 116 class G1RegionMappingChangedListener : public G1MappingChangedListener { 117 private: 118 void reset_from_card_cache(uint start_idx, size_t num_regions); 119 public: 120 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 121 }; 122 123 class G1CollectedHeap : public CollectedHeap { 124 friend class G1FreeCollectionSetTask; 125 friend class VM_CollectForMetadataAllocation; 126 friend class VM_G1CollectForAllocation; 127 friend class VM_G1CollectFull; 128 friend class VMStructs; 129 friend class MutatorAllocRegion; 130 friend class G1FullCollector; 131 friend class G1GCAllocRegion; 132 friend class G1HeapVerifier; 133 134 // Closures used in implementation. 135 friend class G1ParScanThreadState; 136 friend class G1ParScanThreadStateSet; 137 friend class G1ParTask; 138 friend class G1PLABAllocator; 139 friend class G1PrepareCompactClosure; 140 141 // Other related classes. 142 friend class HeapRegionClaimer; 143 144 // Testing classes. 145 friend class G1CheckCSetFastTableClosure; 146 147 private: 148 G1YoungRemSetSamplingThread* _young_gen_sampling_thread; 149 150 WorkGang* _workers; 151 G1CollectorPolicy* _collector_policy; 152 153 GCMemoryManager _memory_manager; 154 GCMemoryManager _full_gc_memory_manager; 155 156 MemoryPool* _eden_pool; 157 MemoryPool* _survivor_pool; 158 MemoryPool* _old_pool; 159 160 static size_t _humongous_object_threshold_in_words; 161 162 // The secondary free list which contains regions that have been 163 // freed up during the cleanup process. This will be appended to 164 // the master free list when appropriate. 165 FreeRegionList _secondary_free_list; 166 167 // It keeps track of the old regions. 168 HeapRegionSet _old_set; 169 170 // It keeps track of the humongous regions. 171 HeapRegionSet _humongous_set; 172 173 virtual void initialize_serviceability(); 174 175 void eagerly_reclaim_humongous_regions(); 176 // Start a new incremental collection set for the next pause. 177 void start_new_collection_set(); 178 179 // The number of regions we could create by expansion. 180 uint _expansion_regions; 181 182 // The block offset table for the G1 heap. 183 G1BlockOffsetTable* _bot; 184 185 // Tears down the region sets / lists so that they are empty and the 186 // regions on the heap do not belong to a region set / list. The 187 // only exception is the humongous set which we leave unaltered. If 188 // free_list_only is true, it will only tear down the master free 189 // list. It is called before a Full GC (free_list_only == false) or 190 // before heap shrinking (free_list_only == true). 191 void tear_down_region_sets(bool free_list_only); 192 193 // Rebuilds the region sets / lists so that they are repopulated to 194 // reflect the contents of the heap. The only exception is the 195 // humongous set which was not torn down in the first place. If 196 // free_list_only is true, it will only rebuild the master free 197 // list. It is called after a Full GC (free_list_only == false) or 198 // after heap shrinking (free_list_only == true). 199 void rebuild_region_sets(bool free_list_only); 200 201 // Callback for region mapping changed events. 202 G1RegionMappingChangedListener _listener; 203 204 // The sequence of all heap regions in the heap. 205 HeapRegionManager _hrm; 206 207 // Manages all allocations with regions except humongous object allocations. 208 G1Allocator* _allocator; 209 210 // Manages all heap verification. 211 G1HeapVerifier* _verifier; 212 213 // Outside of GC pauses, the number of bytes used in all regions other 214 // than the current allocation region(s). 215 size_t _summary_bytes_used; 216 217 void increase_used(size_t bytes); 218 void decrease_used(size_t bytes); 219 220 void set_used(size_t bytes); 221 222 // Class that handles archive allocation ranges. 223 G1ArchiveAllocator* _archive_allocator; 224 225 // GC allocation statistics policy for survivors. 226 G1EvacStats _survivor_evac_stats; 227 228 // GC allocation statistics policy for tenured objects. 229 G1EvacStats _old_evac_stats; 230 231 // It specifies whether we should attempt to expand the heap after a 232 // region allocation failure. If heap expansion fails we set this to 233 // false so that we don't re-attempt the heap expansion (it's likely 234 // that subsequent expansion attempts will also fail if one fails). 235 // Currently, it is only consulted during GC and it's reset at the 236 // start of each GC. 237 bool _expand_heap_after_alloc_failure; 238 239 // Helper for monitoring and management support. 240 G1MonitoringSupport* _g1mm; 241 242 // Records whether the region at the given index is (still) a 243 // candidate for eager reclaim. Only valid for humongous start 244 // regions; other regions have unspecified values. Humongous start 245 // regions are initialized at start of collection pause, with 246 // candidates removed from the set as they are found reachable from 247 // roots or the young generation. 248 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 249 protected: 250 bool default_value() const { return false; } 251 public: 252 void clear() { G1BiasedMappedArray<bool>::clear(); } 253 void set_candidate(uint region, bool value) { 254 set_by_index(region, value); 255 } 256 bool is_candidate(uint region) { 257 return get_by_index(region); 258 } 259 }; 260 261 HumongousReclaimCandidates _humongous_reclaim_candidates; 262 // Stores whether during humongous object registration we found candidate regions. 263 // If not, we can skip a few steps. 264 bool _has_humongous_reclaim_candidates; 265 266 volatile uint _gc_time_stamp; 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 // Clear RSets after a compaction. It also resets the GC time stamps. 300 void clear_rsets_post_compaction(); 301 302 // If the HR printer is active, dump the state of the regions in the 303 // heap after a compaction. 304 void print_hrm_post_compaction(); 305 306 // Create a memory mapper for auxiliary data structures of the given size and 307 // translation factor. 308 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 309 size_t size, 310 size_t translation_factor); 311 312 static G1Policy* create_g1_policy(STWGCTimer* gc_timer); 313 314 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 315 316 // These are macros so that, if the assert fires, we get the correct 317 // line number, file, etc. 318 319 #define heap_locking_asserts_params(_extra_message_) \ 320 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 321 (_extra_message_), \ 322 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 323 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 324 BOOL_TO_STR(Thread::current()->is_VM_thread()) 325 326 #define assert_heap_locked() \ 327 do { \ 328 assert(Heap_lock->owned_by_self(), \ 329 heap_locking_asserts_params("should be holding the Heap_lock")); \ 330 } while (0) 331 332 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 333 do { \ 334 assert(Heap_lock->owned_by_self() || \ 335 (SafepointSynchronize::is_at_safepoint() && \ 336 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 337 heap_locking_asserts_params("should be holding the Heap_lock or " \ 338 "should be at a safepoint")); \ 339 } while (0) 340 341 #define assert_heap_locked_and_not_at_safepoint() \ 342 do { \ 343 assert(Heap_lock->owned_by_self() && \ 344 !SafepointSynchronize::is_at_safepoint(), \ 345 heap_locking_asserts_params("should be holding the Heap_lock and " \ 346 "should not be at a safepoint")); \ 347 } while (0) 348 349 #define assert_heap_not_locked() \ 350 do { \ 351 assert(!Heap_lock->owned_by_self(), \ 352 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 353 } while (0) 354 355 #define assert_heap_not_locked_and_not_at_safepoint() \ 356 do { \ 357 assert(!Heap_lock->owned_by_self() && \ 358 !SafepointSynchronize::is_at_safepoint(), \ 359 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 360 "should not be at a safepoint")); \ 361 } while (0) 362 363 #define assert_at_safepoint(_should_be_vm_thread_) \ 364 do { \ 365 assert(SafepointSynchronize::is_at_safepoint() && \ 366 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 367 heap_locking_asserts_params("should be at a safepoint")); \ 368 } while (0) 369 370 #define assert_not_at_safepoint() \ 371 do { \ 372 assert(!SafepointSynchronize::is_at_safepoint(), \ 373 heap_locking_asserts_params("should not be at a safepoint")); \ 374 } while (0) 375 376 protected: 377 378 // The young region list. 379 G1EdenRegions _eden; 380 G1SurvivorRegions _survivor; 381 382 STWGCTimer* _gc_timer_stw; 383 384 G1NewTracer* _gc_tracer_stw; 385 386 // The current policy object for the collector. 387 G1Policy* _g1_policy; 388 G1HeapSizingPolicy* _heap_sizing_policy; 389 390 G1CollectionSet _collection_set; 391 392 // This is the second level of trying to allocate a new region. If 393 // new_region() didn't find a region on the free_list, this call will 394 // check whether there's anything available on the 395 // secondary_free_list and/or wait for more regions to appear on 396 // that list, if _free_regions_coming is set. 397 HeapRegion* new_region_try_secondary_free_list(bool is_old); 398 399 // Try to allocate a single non-humongous HeapRegion sufficient for 400 // an allocation of the given word_size. If do_expand is true, 401 // attempt to expand the heap if necessary to satisfy the allocation 402 // request. If the region is to be used as an old region or for a 403 // humongous object, set is_old to true. If not, to false. 404 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 405 406 // Initialize a contiguous set of free regions of length num_regions 407 // and starting at index first so that they appear as a single 408 // humongous region. 409 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 410 uint num_regions, 411 size_t word_size, 412 AllocationContext_t context); 413 414 // Attempt to allocate a humongous object of the given size. Return 415 // NULL if unsuccessful. 416 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 417 418 // The following two methods, allocate_new_tlab() and 419 // mem_allocate(), are the two main entry points from the runtime 420 // into the G1's allocation routines. They have the following 421 // assumptions: 422 // 423 // * They should both be called outside safepoints. 424 // 425 // * They should both be called without holding the Heap_lock. 426 // 427 // * All allocation requests for new TLABs should go to 428 // allocate_new_tlab(). 429 // 430 // * All non-TLAB allocation requests should go to mem_allocate(). 431 // 432 // * If either call cannot satisfy the allocation request using the 433 // current allocating region, they will try to get a new one. If 434 // this fails, they will attempt to do an evacuation pause and 435 // retry the allocation. 436 // 437 // * If all allocation attempts fail, even after trying to schedule 438 // an evacuation pause, allocate_new_tlab() will return NULL, 439 // whereas mem_allocate() will attempt a heap expansion and/or 440 // schedule a Full GC. 441 // 442 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 443 // should never be called with word_size being humongous. All 444 // humongous allocation requests should go to mem_allocate() which 445 // will satisfy them with a special path. 446 447 virtual HeapWord* allocate_new_tlab(size_t word_size); 448 449 virtual HeapWord* mem_allocate(size_t word_size, 450 bool* gc_overhead_limit_was_exceeded); 451 452 // First-level mutator allocation attempt: try to allocate out of 453 // the mutator alloc region without taking the Heap_lock. This 454 // should only be used for non-humongous allocations. 455 inline HeapWord* attempt_allocation(size_t word_size); 456 457 // Second-level mutator allocation attempt: take the Heap_lock and 458 // retry the allocation attempt, potentially scheduling a GC 459 // pause. This should only be used for non-humongous allocations. 460 HeapWord* attempt_allocation_slow(size_t word_size, 461 AllocationContext_t context); 462 463 // Takes the Heap_lock and attempts a humongous allocation. It can 464 // potentially schedule a GC pause. 465 HeapWord* attempt_allocation_humongous(size_t word_size); 466 467 // Allocation attempt that should be called during safepoints (e.g., 468 // at the end of a successful GC). expect_null_mutator_alloc_region 469 // specifies whether the mutator alloc region is expected to be NULL 470 // or not. 471 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 472 AllocationContext_t context, 473 bool expect_null_mutator_alloc_region); 474 475 // These methods are the "callbacks" from the G1AllocRegion class. 476 477 // For mutator alloc regions. 478 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 479 void retire_mutator_alloc_region(HeapRegion* alloc_region, 480 size_t allocated_bytes); 481 482 // For GC alloc regions. 483 bool has_more_regions(InCSetState dest); 484 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest); 485 void retire_gc_alloc_region(HeapRegion* alloc_region, 486 size_t allocated_bytes, InCSetState dest); 487 488 // - if explicit_gc is true, the GC is for a System.gc() etc, 489 // otherwise it's for a failed allocation. 490 // - if clear_all_soft_refs is true, all soft references should be 491 // cleared during the GC. 492 // - it returns false if it is unable to do the collection due to the 493 // GC locker being active, true otherwise. 494 bool do_full_collection(bool explicit_gc, 495 bool clear_all_soft_refs); 496 497 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 498 virtual void do_full_collection(bool clear_all_soft_refs); 499 500 // Resize the heap if necessary after a full collection. 501 void resize_if_necessary_after_full_collection(); 502 503 // Callback from VM_G1CollectForAllocation operation. 504 // This function does everything necessary/possible to satisfy a 505 // failed allocation request (including collection, expansion, etc.) 506 HeapWord* satisfy_failed_allocation(size_t word_size, 507 AllocationContext_t context, 508 bool* succeeded); 509 private: 510 // Internal helpers used during full GC to split it up to 511 // increase readability. 512 void abort_concurrent_cycle(); 513 void verify_before_full_collection(bool explicit_gc); 514 void prepare_heap_for_full_collection(); 515 void prepare_heap_for_mutators(); 516 void abort_refinement(); 517 void verify_after_full_collection(); 518 void print_heap_after_full_collection(G1HeapTransition* heap_transition); 519 520 // Helper method for satisfy_failed_allocation() 521 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 522 AllocationContext_t context, 523 bool do_gc, 524 bool clear_all_soft_refs, 525 bool expect_null_mutator_alloc_region, 526 bool* gc_succeeded); 527 528 protected: 529 // Attempting to expand the heap sufficiently 530 // to support an allocation of the given "word_size". If 531 // successful, perform the allocation and return the address of the 532 // allocated block, or else "NULL". 533 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 534 535 // Preserve any referents discovered by concurrent marking that have not yet been 536 // copied by the STW pause. 537 void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states); 538 // Process any reference objects discovered during 539 // an incremental evacuation pause. 540 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 541 542 // Enqueue any remaining discovered references 543 // after processing. 544 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states); 545 546 // Merges the information gathered on a per-thread basis for all worker threads 547 // during GC into global variables. 548 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states); 549 public: 550 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; } 551 552 WorkGang* workers() const { return _workers; } 553 554 G1Allocator* allocator() { 555 return _allocator; 556 } 557 558 G1HeapVerifier* verifier() { 559 return _verifier; 560 } 561 562 G1MonitoringSupport* g1mm() { 563 assert(_g1mm != NULL, "should have been initialized"); 564 return _g1mm; 565 } 566 567 // Expand the garbage-first heap by at least the given size (in bytes!). 568 // Returns true if the heap was expanded by the requested amount; 569 // false otherwise. 570 // (Rounds up to a HeapRegion boundary.) 571 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL); 572 573 // Returns the PLAB statistics for a given destination. 574 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 575 576 // Determines PLAB size for a given destination. 577 inline size_t desired_plab_sz(InCSetState dest); 578 579 // Do anything common to GC's. 580 void gc_prologue(bool full); 581 void gc_epilogue(bool full); 582 583 // Modify the reclaim candidate set and test for presence. 584 // These are only valid for starts_humongous regions. 585 inline void set_humongous_reclaim_candidate(uint region, bool value); 586 inline bool is_humongous_reclaim_candidate(uint region); 587 588 // Remove from the reclaim candidate set. Also remove from the 589 // collection set so that later encounters avoid the slow path. 590 inline void set_humongous_is_live(oop obj); 591 592 // Register the given region to be part of the collection set. 593 inline void register_humongous_region_with_cset(uint index); 594 // Register regions with humongous objects (actually on the start region) in 595 // the in_cset_fast_test table. 596 void register_humongous_regions_with_cset(); 597 // We register a region with the fast "in collection set" test. We 598 // simply set to true the array slot corresponding to this region. 599 void register_young_region_with_cset(HeapRegion* r) { 600 _in_cset_fast_test.set_in_young(r->hrm_index()); 601 } 602 void register_old_region_with_cset(HeapRegion* r) { 603 _in_cset_fast_test.set_in_old(r->hrm_index()); 604 } 605 inline void register_ext_region_with_cset(HeapRegion* r) { 606 _in_cset_fast_test.set_ext(r->hrm_index()); 607 } 608 void clear_in_cset(const HeapRegion* hr) { 609 _in_cset_fast_test.clear(hr); 610 } 611 612 void clear_cset_fast_test() { 613 _in_cset_fast_test.clear(); 614 } 615 616 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 617 618 // This is called at the start of either a concurrent cycle or a Full 619 // GC to update the number of old marking cycles started. 620 void increment_old_marking_cycles_started(); 621 622 // This is called at the end of either a concurrent cycle or a Full 623 // GC to update the number of old marking cycles completed. Those two 624 // can happen in a nested fashion, i.e., we start a concurrent 625 // cycle, a Full GC happens half-way through it which ends first, 626 // and then the cycle notices that a Full GC happened and ends 627 // too. The concurrent parameter is a boolean to help us do a bit 628 // tighter consistency checking in the method. If concurrent is 629 // false, the caller is the inner caller in the nesting (i.e., the 630 // Full GC). If concurrent is true, the caller is the outer caller 631 // in this nesting (i.e., the concurrent cycle). Further nesting is 632 // not currently supported. The end of this call also notifies 633 // the FullGCCount_lock in case a Java thread is waiting for a full 634 // GC to happen (e.g., it called System.gc() with 635 // +ExplicitGCInvokesConcurrent). 636 void increment_old_marking_cycles_completed(bool concurrent); 637 638 uint old_marking_cycles_completed() { 639 return _old_marking_cycles_completed; 640 } 641 642 G1HRPrinter* hr_printer() { return &_hr_printer; } 643 644 // Allocates a new heap region instance. 645 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 646 647 // Allocate the highest free region in the reserved heap. This will commit 648 // regions as necessary. 649 HeapRegion* alloc_highest_free_region(); 650 651 // Frees a non-humongous region by initializing its contents and 652 // adding it to the free list that's passed as a parameter (this is 653 // usually a local list which will be appended to the master free 654 // list later). The used bytes of freed regions are accumulated in 655 // pre_used. If skip_remset is true, the region's RSet will not be freed 656 // up. If skip_hot_card_cache is true, the region's hot card cache will not 657 // be freed up. The assumption is that this will be done later. 658 // The locked parameter indicates if the caller has already taken 659 // care of proper synchronization. This may allow some optimizations. 660 void free_region(HeapRegion* hr, 661 FreeRegionList* free_list, 662 bool skip_remset, 663 bool skip_hot_card_cache = false, 664 bool locked = false); 665 666 // It dirties the cards that cover the block so that the post 667 // write barrier never queues anything when updating objects on this 668 // block. It is assumed (and in fact we assert) that the block 669 // belongs to a young region. 670 inline void dirty_young_block(HeapWord* start, size_t word_size); 671 672 // Frees a humongous region by collapsing it into individual regions 673 // and calling free_region() for each of them. The freed regions 674 // will be added to the free list that's passed as a parameter (this 675 // is usually a local list which will be appended to the master free 676 // list later). The used bytes of freed regions are accumulated in 677 // pre_used. If skip_remset is true, the region's RSet will not be freed 678 // up. The assumption is that this will be done later. 679 void free_humongous_region(HeapRegion* hr, 680 FreeRegionList* free_list, 681 bool skip_remset); 682 683 // Facility for allocating in 'archive' regions in high heap memory and 684 // recording the allocated ranges. These should all be called from the 685 // VM thread at safepoints, without the heap lock held. They can be used 686 // to create and archive a set of heap regions which can be mapped at the 687 // same fixed addresses in a subsequent JVM invocation. 688 void begin_archive_alloc_range(bool open = false); 689 690 // Check if the requested size would be too large for an archive allocation. 691 bool is_archive_alloc_too_large(size_t word_size); 692 693 // Allocate memory of the requested size from the archive region. This will 694 // return NULL if the size is too large or if no memory is available. It 695 // does not trigger a garbage collection. 696 HeapWord* archive_mem_allocate(size_t word_size); 697 698 // Optionally aligns the end address and returns the allocated ranges in 699 // an array of MemRegions in order of ascending addresses. 700 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 701 size_t end_alignment_in_bytes = 0); 702 703 // Facility for allocating a fixed range within the heap and marking 704 // the containing regions as 'archive'. For use at JVM init time, when the 705 // caller may mmap archived heap data at the specified range(s). 706 // Verify that the MemRegions specified in the argument array are within the 707 // reserved heap. 708 bool check_archive_addresses(MemRegion* range, size_t count); 709 710 // Commit the appropriate G1 regions containing the specified MemRegions 711 // and mark them as 'archive' regions. The regions in the array must be 712 // non-overlapping and in order of ascending address. 713 bool alloc_archive_regions(MemRegion* range, size_t count, bool open); 714 715 // Insert any required filler objects in the G1 regions around the specified 716 // ranges to make the regions parseable. This must be called after 717 // alloc_archive_regions, and after class loading has occurred. 718 void fill_archive_regions(MemRegion* range, size_t count); 719 720 // For each of the specified MemRegions, uncommit the containing G1 regions 721 // which had been allocated by alloc_archive_regions. This should be called 722 // rather than fill_archive_regions at JVM init time if the archive file 723 // mapping failed, with the same non-overlapping and sorted MemRegion array. 724 void dealloc_archive_regions(MemRegion* range, size_t count); 725 726 protected: 727 728 // Shrink the garbage-first heap by at most the given size (in bytes!). 729 // (Rounds down to a HeapRegion boundary.) 730 virtual void shrink(size_t expand_bytes); 731 void shrink_helper(size_t expand_bytes); 732 733 #if TASKQUEUE_STATS 734 static void print_taskqueue_stats_hdr(outputStream* const st); 735 void print_taskqueue_stats() const; 736 void reset_taskqueue_stats(); 737 #endif // TASKQUEUE_STATS 738 739 // Schedule the VM operation that will do an evacuation pause to 740 // satisfy an allocation request of word_size. *succeeded will 741 // return whether the VM operation was successful (it did do an 742 // evacuation pause) or not (another thread beat us to it or the GC 743 // locker was active). Given that we should not be holding the 744 // Heap_lock when we enter this method, we will pass the 745 // gc_count_before (i.e., total_collections()) as a parameter since 746 // it has to be read while holding the Heap_lock. Currently, both 747 // methods that call do_collection_pause() release the Heap_lock 748 // before the call, so it's easy to read gc_count_before just before. 749 HeapWord* do_collection_pause(size_t word_size, 750 uint gc_count_before, 751 bool* succeeded, 752 GCCause::Cause gc_cause); 753 754 void wait_for_root_region_scanning(); 755 756 // The guts of the incremental collection pause, executed by the vm 757 // thread. It returns false if it is unable to do the collection due 758 // to the GC locker being active, true otherwise 759 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 760 761 // Actually do the work of evacuating the collection set. 762 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states); 763 764 void pre_evacuate_collection_set(); 765 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 766 767 // Print the header for the per-thread termination statistics. 768 static void print_termination_stats_hdr(); 769 // Print actual per-thread termination statistics. 770 void print_termination_stats(uint worker_id, 771 double elapsed_ms, 772 double strong_roots_ms, 773 double term_ms, 774 size_t term_attempts, 775 size_t alloc_buffer_waste, 776 size_t undo_waste) const; 777 // Update object copying statistics. 778 void record_obj_copy_mem_stats(); 779 780 // The hot card cache for remembered set insertion optimization. 781 G1HotCardCache* _hot_card_cache; 782 783 // The g1 remembered set of the heap. 784 G1RemSet* _g1_rem_set; 785 786 // A set of cards that cover the objects for which the Rsets should be updated 787 // concurrently after the collection. 788 DirtyCardQueueSet _dirty_card_queue_set; 789 790 // After a collection pause, convert the regions in the collection set into free 791 // regions. 792 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 793 794 // Abandon the current collection set without recording policy 795 // statistics or updating free lists. 796 void abandon_collection_set(G1CollectionSet* collection_set); 797 798 // The concurrent marker (and the thread it runs in.) 799 G1ConcurrentMark* _cm; 800 ConcurrentMarkThread* _cmThread; 801 802 // The concurrent refiner. 803 G1ConcurrentRefine* _cr; 804 805 // The parallel task queues 806 RefToScanQueueSet *_task_queues; 807 808 // True iff a evacuation has failed in the current collection. 809 bool _evacuation_failed; 810 811 EvacuationFailedInfo* _evacuation_failed_info_array; 812 813 // Failed evacuations cause some logical from-space objects to have 814 // forwarding pointers to themselves. Reset them. 815 void remove_self_forwarding_pointers(); 816 817 // Restore the objects in the regions in the collection set after an 818 // evacuation failure. 819 void restore_after_evac_failure(); 820 821 PreservedMarksSet _preserved_marks_set; 822 823 // Preserve the mark of "obj", if necessary, in preparation for its mark 824 // word being overwritten with a self-forwarding-pointer. 825 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 826 827 #ifndef PRODUCT 828 // Support for forcing evacuation failures. Analogous to 829 // PromotionFailureALot for the other collectors. 830 831 // Records whether G1EvacuationFailureALot should be in effect 832 // for the current GC 833 bool _evacuation_failure_alot_for_current_gc; 834 835 // Used to record the GC number for interval checking when 836 // determining whether G1EvaucationFailureALot is in effect 837 // for the current GC. 838 size_t _evacuation_failure_alot_gc_number; 839 840 // Count of the number of evacuations between failures. 841 volatile size_t _evacuation_failure_alot_count; 842 843 // Set whether G1EvacuationFailureALot should be in effect 844 // for the current GC (based upon the type of GC and which 845 // command line flags are set); 846 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 847 bool during_initial_mark, 848 bool during_marking); 849 850 inline void set_evacuation_failure_alot_for_current_gc(); 851 852 // Return true if it's time to cause an evacuation failure. 853 inline bool evacuation_should_fail(); 854 855 // Reset the G1EvacuationFailureALot counters. Should be called at 856 // the end of an evacuation pause in which an evacuation failure occurred. 857 inline void reset_evacuation_should_fail(); 858 #endif // !PRODUCT 859 860 // ("Weak") Reference processing support. 861 // 862 // G1 has 2 instances of the reference processor class. One 863 // (_ref_processor_cm) handles reference object discovery 864 // and subsequent processing during concurrent marking cycles. 865 // 866 // The other (_ref_processor_stw) handles reference object 867 // discovery and processing during full GCs and incremental 868 // evacuation pauses. 869 // 870 // During an incremental pause, reference discovery will be 871 // temporarily disabled for _ref_processor_cm and will be 872 // enabled for _ref_processor_stw. At the end of the evacuation 873 // pause references discovered by _ref_processor_stw will be 874 // processed and discovery will be disabled. The previous 875 // setting for reference object discovery for _ref_processor_cm 876 // will be re-instated. 877 // 878 // At the start of marking: 879 // * Discovery by the CM ref processor is verified to be inactive 880 // and it's discovered lists are empty. 881 // * Discovery by the CM ref processor is then enabled. 882 // 883 // At the end of marking: 884 // * Any references on the CM ref processor's discovered 885 // lists are processed (possibly MT). 886 // 887 // At the start of full GC we: 888 // * Disable discovery by the CM ref processor and 889 // empty CM ref processor's discovered lists 890 // (without processing any entries). 891 // * Verify that the STW ref processor is inactive and it's 892 // discovered lists are empty. 893 // * Temporarily set STW ref processor discovery as single threaded. 894 // * Temporarily clear the STW ref processor's _is_alive_non_header 895 // field. 896 // * Finally enable discovery by the STW ref processor. 897 // 898 // The STW ref processor is used to record any discovered 899 // references during the full GC. 900 // 901 // At the end of a full GC we: 902 // * Enqueue any reference objects discovered by the STW ref processor 903 // that have non-live referents. This has the side-effect of 904 // making the STW ref processor inactive by disabling discovery. 905 // * Verify that the CM ref processor is still inactive 906 // and no references have been placed on it's discovered 907 // lists (also checked as a precondition during initial marking). 908 909 // The (stw) reference processor... 910 ReferenceProcessor* _ref_processor_stw; 911 912 // During reference object discovery, the _is_alive_non_header 913 // closure (if non-null) is applied to the referent object to 914 // determine whether the referent is live. If so then the 915 // reference object does not need to be 'discovered' and can 916 // be treated as a regular oop. This has the benefit of reducing 917 // the number of 'discovered' reference objects that need to 918 // be processed. 919 // 920 // Instance of the is_alive closure for embedding into the 921 // STW reference processor as the _is_alive_non_header field. 922 // Supplying a value for the _is_alive_non_header field is 923 // optional but doing so prevents unnecessary additions to 924 // the discovered lists during reference discovery. 925 G1STWIsAliveClosure _is_alive_closure_stw; 926 927 // The (concurrent marking) reference processor... 928 ReferenceProcessor* _ref_processor_cm; 929 930 // Instance of the concurrent mark is_alive closure for embedding 931 // into the Concurrent Marking reference processor as the 932 // _is_alive_non_header field. Supplying a value for the 933 // _is_alive_non_header field is optional but doing so prevents 934 // unnecessary additions to the discovered lists during reference 935 // discovery. 936 G1CMIsAliveClosure _is_alive_closure_cm; 937 938 volatile bool _free_regions_coming; 939 940 public: 941 942 RefToScanQueue *task_queue(uint i) const; 943 944 uint num_task_queues() const; 945 946 // A set of cards where updates happened during the GC 947 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 948 949 // Create a G1CollectedHeap with the specified policy. 950 // Must call the initialize method afterwards. 951 // May not return if something goes wrong. 952 G1CollectedHeap(G1CollectorPolicy* policy); 953 954 private: 955 jint initialize_concurrent_refinement(); 956 jint initialize_young_gen_sampling_thread(); 957 public: 958 // Initialize the G1CollectedHeap to have the initial and 959 // maximum sizes and remembered and barrier sets 960 // specified by the policy object. 961 jint initialize(); 962 963 virtual void stop(); 964 virtual void safepoint_synchronize_begin(); 965 virtual void safepoint_synchronize_end(); 966 967 // Return the (conservative) maximum heap alignment for any G1 heap 968 static size_t conservative_max_heap_alignment(); 969 970 // Does operations required after initialization has been done. 971 void post_initialize(); 972 973 // Initialize weak reference processing. 974 void ref_processing_init(); 975 976 virtual Name kind() const { 977 return CollectedHeap::G1CollectedHeap; 978 } 979 980 virtual const char* name() const { 981 return "G1"; 982 } 983 984 const G1CollectorState* collector_state() const { return &_collector_state; } 985 G1CollectorState* collector_state() { return &_collector_state; } 986 987 // The current policy object for the collector. 988 G1Policy* g1_policy() const { return _g1_policy; } 989 990 const G1CollectionSet* collection_set() const { return &_collection_set; } 991 G1CollectionSet* collection_set() { return &_collection_set; } 992 993 virtual CollectorPolicy* collector_policy() const; 994 995 // Adaptive size policy. No such thing for g1. 996 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 997 998 virtual GrowableArray<GCMemoryManager*> memory_managers(); 999 virtual GrowableArray<MemoryPool*> memory_pools(); 1000 1001 // The rem set and barrier set. 1002 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1003 1004 // Try to minimize the remembered set. 1005 void scrub_rem_set(); 1006 1007 uint get_gc_time_stamp() { 1008 return _gc_time_stamp; 1009 } 1010 1011 inline void reset_gc_time_stamp(); 1012 1013 void check_gc_time_stamps() PRODUCT_RETURN; 1014 1015 inline void increment_gc_time_stamp(); 1016 1017 // Reset the given region's GC timestamp. If it's starts humongous, 1018 // also reset the GC timestamp of its corresponding 1019 // continues humongous regions too. 1020 void reset_gc_time_stamps(HeapRegion* hr); 1021 1022 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 1023 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i); 1024 1025 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. 1026 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i); 1027 1028 // The shared block offset table array. 1029 G1BlockOffsetTable* bot() const { return _bot; } 1030 1031 // Reference Processing accessors 1032 1033 // The STW reference processor.... 1034 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1035 1036 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1037 1038 // The Concurrent Marking reference processor... 1039 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1040 1041 size_t unused_committed_regions_in_bytes() const; 1042 virtual size_t capacity() const; 1043 virtual size_t used() const; 1044 // This should be called when we're not holding the heap lock. The 1045 // result might be a bit inaccurate. 1046 size_t used_unlocked() const; 1047 size_t recalculate_used() const; 1048 1049 // These virtual functions do the actual allocation. 1050 // Some heaps may offer a contiguous region for shared non-blocking 1051 // allocation, via inlined code (by exporting the address of the top and 1052 // end fields defining the extent of the contiguous allocation region.) 1053 // But G1CollectedHeap doesn't yet support this. 1054 1055 virtual bool is_maximal_no_gc() const { 1056 return _hrm.available() == 0; 1057 } 1058 1059 // Returns whether there are any regions left in the heap for allocation. 1060 bool has_regions_left_for_allocation() const { 1061 return !is_maximal_no_gc() || num_free_regions() != 0; 1062 } 1063 1064 // The current number of regions in the heap. 1065 uint num_regions() const { return _hrm.length(); } 1066 1067 // The max number of regions in the heap. 1068 uint max_regions() const { return _hrm.max_length(); } 1069 1070 // The number of regions that are completely free. 1071 uint num_free_regions() const { return _hrm.num_free_regions(); } 1072 1073 MemoryUsage get_auxiliary_data_memory_usage() const { 1074 return _hrm.get_auxiliary_data_memory_usage(); 1075 } 1076 1077 // The number of regions that are not completely free. 1078 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1079 1080 #ifdef ASSERT 1081 bool is_on_master_free_list(HeapRegion* hr) { 1082 return _hrm.is_free(hr); 1083 } 1084 #endif // ASSERT 1085 1086 // Wrapper for the region list operations that can be called from 1087 // methods outside this class. 1088 1089 void secondary_free_list_add(FreeRegionList* list) { 1090 _secondary_free_list.add_ordered(list); 1091 } 1092 1093 void append_secondary_free_list() { 1094 _hrm.insert_list_into_free_list(&_secondary_free_list); 1095 } 1096 1097 void append_secondary_free_list_if_not_empty_with_lock() { 1098 // If the secondary free list looks empty there's no reason to 1099 // take the lock and then try to append it. 1100 if (!_secondary_free_list.is_empty()) { 1101 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1102 append_secondary_free_list(); 1103 } 1104 } 1105 1106 inline void old_set_add(HeapRegion* hr); 1107 inline void old_set_remove(HeapRegion* hr); 1108 1109 size_t non_young_capacity_bytes() { 1110 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes; 1111 } 1112 1113 void set_free_regions_coming(); 1114 void reset_free_regions_coming(); 1115 bool free_regions_coming() { return _free_regions_coming; } 1116 void wait_while_free_regions_coming(); 1117 1118 // Determine whether the given region is one that we are using as an 1119 // old GC alloc region. 1120 bool is_old_gc_alloc_region(HeapRegion* hr); 1121 1122 // Perform a collection of the heap; intended for use in implementing 1123 // "System.gc". This probably implies as full a collection as the 1124 // "CollectedHeap" supports. 1125 virtual void collect(GCCause::Cause cause); 1126 1127 // True iff an evacuation has failed in the most-recent collection. 1128 bool evacuation_failed() { return _evacuation_failed; } 1129 1130 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed); 1131 void prepend_to_freelist(FreeRegionList* list); 1132 void decrement_summary_bytes(size_t bytes); 1133 1134 virtual bool is_in(const void* p) const; 1135 #ifdef ASSERT 1136 // Returns whether p is in one of the available areas of the heap. Slow but 1137 // extensive version. 1138 bool is_in_exact(const void* p) const; 1139 #endif 1140 1141 // Return "TRUE" iff the given object address is within the collection 1142 // set. Assumes that the reference points into the heap. 1143 inline bool is_in_cset(const HeapRegion *hr); 1144 inline bool is_in_cset(oop obj); 1145 inline bool is_in_cset(HeapWord* addr); 1146 1147 inline bool is_in_cset_or_humongous(const oop obj); 1148 1149 private: 1150 // This array is used for a quick test on whether a reference points into 1151 // the collection set or not. Each of the array's elements denotes whether the 1152 // corresponding region is in the collection set or not. 1153 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1154 1155 public: 1156 1157 inline InCSetState in_cset_state(const oop obj); 1158 1159 // Return "TRUE" iff the given object address is in the reserved 1160 // region of g1. 1161 bool is_in_g1_reserved(const void* p) const { 1162 return _hrm.reserved().contains(p); 1163 } 1164 1165 // Returns a MemRegion that corresponds to the space that has been 1166 // reserved for the heap 1167 MemRegion g1_reserved() const { 1168 return _hrm.reserved(); 1169 } 1170 1171 virtual bool is_in_closed_subset(const void* p) const; 1172 1173 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1174 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set()); 1175 } 1176 1177 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; } 1178 1179 // Iteration functions. 1180 1181 // Iterate over all objects, calling "cl.do_object" on each. 1182 virtual void object_iterate(ObjectClosure* cl); 1183 1184 virtual void safe_object_iterate(ObjectClosure* cl) { 1185 object_iterate(cl); 1186 } 1187 1188 // Iterate over heap regions, in address order, terminating the 1189 // iteration early if the "do_heap_region" method returns "true". 1190 void heap_region_iterate(HeapRegionClosure* blk) const; 1191 1192 // Return the region with the given index. It assumes the index is valid. 1193 inline HeapRegion* region_at(uint index) const; 1194 1195 // Return the next region (by index) that is part of the same 1196 // humongous object that hr is part of. 1197 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1198 1199 // Calculate the region index of the given address. Given address must be 1200 // within the heap. 1201 inline uint addr_to_region(HeapWord* addr) const; 1202 1203 inline HeapWord* bottom_addr_for_region(uint index) const; 1204 1205 // Two functions to iterate over the heap regions in parallel. Threads 1206 // compete using the HeapRegionClaimer to claim the regions before 1207 // applying the closure on them. 1208 // The _from_worker_offset version uses the HeapRegionClaimer and 1209 // the worker id to calculate a start offset to prevent all workers to 1210 // start from the point. 1211 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 1212 HeapRegionClaimer* hrclaimer, 1213 uint worker_id) const; 1214 1215 void heap_region_par_iterate_from_start(HeapRegionClosure* cl, 1216 HeapRegionClaimer* hrclaimer) const; 1217 1218 // Iterate over the regions (if any) in the current collection set. 1219 void collection_set_iterate(HeapRegionClosure* blk); 1220 1221 // Iterate over the regions (if any) in the current collection set. Starts the 1222 // iteration over the entire collection set so that the start regions of a given 1223 // worker id over the set active_workers are evenly spread across the set of 1224 // collection set regions. 1225 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id); 1226 1227 // Returns the HeapRegion that contains addr. addr must not be NULL. 1228 template <class T> 1229 inline HeapRegion* heap_region_containing(const T addr) const; 1230 1231 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1232 // each address in the (reserved) heap is a member of exactly 1233 // one block. The defining characteristic of a block is that it is 1234 // possible to find its size, and thus to progress forward to the next 1235 // block. (Blocks may be of different sizes.) Thus, blocks may 1236 // represent Java objects, or they might be free blocks in a 1237 // free-list-based heap (or subheap), as long as the two kinds are 1238 // distinguishable and the size of each is determinable. 1239 1240 // Returns the address of the start of the "block" that contains the 1241 // address "addr". We say "blocks" instead of "object" since some heaps 1242 // may not pack objects densely; a chunk may either be an object or a 1243 // non-object. 1244 virtual HeapWord* block_start(const void* addr) const; 1245 1246 // Requires "addr" to be the start of a chunk, and returns its size. 1247 // "addr + size" is required to be the start of a new chunk, or the end 1248 // of the active area of the heap. 1249 virtual size_t block_size(const HeapWord* addr) const; 1250 1251 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1252 // the block is an object. 1253 virtual bool block_is_obj(const HeapWord* addr) const; 1254 1255 // Section on thread-local allocation buffers (TLABs) 1256 // See CollectedHeap for semantics. 1257 1258 bool supports_tlab_allocation() const; 1259 size_t tlab_capacity(Thread* ignored) const; 1260 size_t tlab_used(Thread* ignored) const; 1261 size_t max_tlab_size() const; 1262 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1263 1264 inline bool is_in_young(const oop obj); 1265 1266 // Returns "true" iff the given word_size is "very large". 1267 static bool is_humongous(size_t word_size) { 1268 // Note this has to be strictly greater-than as the TLABs 1269 // are capped at the humongous threshold and we want to 1270 // ensure that we don't try to allocate a TLAB as 1271 // humongous and that we don't allocate a humongous 1272 // object in a TLAB. 1273 return word_size > _humongous_object_threshold_in_words; 1274 } 1275 1276 // Returns the humongous threshold for a specific region size 1277 static size_t humongous_threshold_for(size_t region_size) { 1278 return (region_size / 2); 1279 } 1280 1281 // Returns the number of regions the humongous object of the given word size 1282 // requires. 1283 static size_t humongous_obj_size_in_regions(size_t word_size); 1284 1285 // Print the maximum heap capacity. 1286 virtual size_t max_capacity() const; 1287 1288 virtual jlong millis_since_last_gc(); 1289 1290 1291 // Convenience function to be used in situations where the heap type can be 1292 // asserted to be this type. 1293 static G1CollectedHeap* heap(); 1294 1295 void set_region_short_lived_locked(HeapRegion* hr); 1296 // add appropriate methods for any other surv rate groups 1297 1298 const G1SurvivorRegions* survivor() const { return &_survivor; } 1299 1300 uint survivor_regions_count() const { 1301 return _survivor.length(); 1302 } 1303 1304 uint eden_regions_count() const { 1305 return _eden.length(); 1306 } 1307 1308 uint young_regions_count() const { 1309 return _eden.length() + _survivor.length(); 1310 } 1311 1312 uint old_regions_count() const { return _old_set.length(); } 1313 1314 uint humongous_regions_count() const { return _humongous_set.length(); } 1315 1316 #ifdef ASSERT 1317 bool check_young_list_empty(); 1318 #endif 1319 1320 // *** Stuff related to concurrent marking. It's not clear to me that so 1321 // many of these need to be public. 1322 1323 // The functions below are helper functions that a subclass of 1324 // "CollectedHeap" can use in the implementation of its virtual 1325 // functions. 1326 // This performs a concurrent marking of the live objects in a 1327 // bitmap off to the side. 1328 void doConcurrentMark(); 1329 1330 bool isMarkedNext(oop obj) const; 1331 1332 // Determine if an object is dead, given the object and also 1333 // the region to which the object belongs. An object is dead 1334 // iff a) it was not allocated since the last mark, b) it 1335 // is not marked, and c) it is not in an archive region. 1336 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1337 return 1338 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) && 1339 !hr->is_archive(); 1340 } 1341 1342 // This function returns true when an object has been 1343 // around since the previous marking and hasn't yet 1344 // been marked during this marking, and is not in an archive region. 1345 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1346 return 1347 !hr->obj_allocated_since_next_marking(obj) && 1348 !isMarkedNext(obj) && 1349 !hr->is_archive(); 1350 } 1351 1352 // Determine if an object is dead, given only the object itself. 1353 // This will find the region to which the object belongs and 1354 // then call the region version of the same function. 1355 1356 // Added if it is NULL it isn't dead. 1357 1358 inline bool is_obj_dead(const oop obj) const; 1359 1360 inline bool is_obj_ill(const oop obj) const; 1361 1362 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const; 1363 inline bool is_obj_dead_full(const oop obj) const; 1364 1365 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1366 1367 // Refinement 1368 1369 G1ConcurrentRefine* concurrent_refine() const { return _cr; } 1370 1371 // Optimized nmethod scanning support routines 1372 1373 // Is an oop scavengeable 1374 virtual bool is_scavengable(oop obj); 1375 1376 // Register the given nmethod with the G1 heap. 1377 virtual void register_nmethod(nmethod* nm); 1378 1379 // Unregister the given nmethod from the G1 heap. 1380 virtual void unregister_nmethod(nmethod* nm); 1381 1382 // Free up superfluous code root memory. 1383 void purge_code_root_memory(); 1384 1385 // Rebuild the strong code root lists for each region 1386 // after a full GC. 1387 void rebuild_strong_code_roots(); 1388 1389 // Partial cleaning used when class unloading is disabled. 1390 // Let the caller choose what structures to clean out: 1391 // - StringTable 1392 // - SymbolTable 1393 // - StringDeduplication structures 1394 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup); 1395 1396 // Complete cleaning used when class unloading is enabled. 1397 // Cleans out all structures handled by partial_cleaning and also the CodeCache. 1398 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); 1399 1400 // Redirty logged cards in the refinement queue. 1401 void redirty_logged_cards(); 1402 // Verification 1403 1404 // Perform any cleanup actions necessary before allowing a verification. 1405 virtual void prepare_for_verify(); 1406 1407 // Perform verification. 1408 1409 // vo == UsePrevMarking -> use "prev" marking information, 1410 // vo == UseNextMarking -> use "next" marking information 1411 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS 1412 // 1413 // NOTE: Only the "prev" marking information is guaranteed to be 1414 // consistent most of the time, so most calls to this should use 1415 // vo == UsePrevMarking. 1416 // Currently, there is only one case where this is called with 1417 // vo == UseNextMarking, which is to verify the "next" marking 1418 // information at the end of remark. 1419 // Currently there is only one place where this is called with 1420 // vo == UseFullMarking, which is to verify the marking during a 1421 // full GC. 1422 void verify(VerifyOption vo); 1423 1424 // WhiteBox testing support. 1425 virtual bool supports_concurrent_phase_control() const; 1426 virtual const char* const* concurrent_phases() const; 1427 virtual bool request_concurrent_phase(const char* phase); 1428 1429 // The methods below are here for convenience and dispatch the 1430 // appropriate method depending on value of the given VerifyOption 1431 // parameter. The values for that parameter, and their meanings, 1432 // are the same as those above. 1433 1434 bool is_obj_dead_cond(const oop obj, 1435 const HeapRegion* hr, 1436 const VerifyOption vo) const; 1437 1438 bool is_obj_dead_cond(const oop obj, 1439 const VerifyOption vo) const; 1440 1441 G1HeapSummary create_g1_heap_summary(); 1442 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1443 1444 // Printing 1445 private: 1446 void print_heap_regions() const; 1447 void print_regions_on(outputStream* st) const; 1448 1449 public: 1450 virtual void print_on(outputStream* st) const; 1451 virtual void print_extended_on(outputStream* st) const; 1452 virtual void print_on_error(outputStream* st) const; 1453 1454 virtual void print_gc_threads_on(outputStream* st) const; 1455 virtual void gc_threads_do(ThreadClosure* tc) const; 1456 1457 // Override 1458 void print_tracing_info() const; 1459 1460 // The following two methods are helpful for debugging RSet issues. 1461 void print_cset_rsets() PRODUCT_RETURN; 1462 void print_all_rsets() PRODUCT_RETURN; 1463 1464 public: 1465 size_t pending_card_num(); 1466 1467 protected: 1468 size_t _max_heap_capacity; 1469 }; 1470 1471 class G1ParEvacuateFollowersClosure : public VoidClosure { 1472 private: 1473 double _start_term; 1474 double _term_time; 1475 size_t _term_attempts; 1476 1477 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 1478 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 1479 protected: 1480 G1CollectedHeap* _g1h; 1481 G1ParScanThreadState* _par_scan_state; 1482 RefToScanQueueSet* _queues; 1483 ParallelTaskTerminator* _terminator; 1484 1485 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 1486 RefToScanQueueSet* queues() { return _queues; } 1487 ParallelTaskTerminator* terminator() { return _terminator; } 1488 1489 public: 1490 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 1491 G1ParScanThreadState* par_scan_state, 1492 RefToScanQueueSet* queues, 1493 ParallelTaskTerminator* terminator) 1494 : _g1h(g1h), _par_scan_state(par_scan_state), 1495 _queues(queues), _terminator(terminator), 1496 _start_term(0.0), _term_time(0.0), _term_attempts(0) {} 1497 1498 void do_void(); 1499 1500 double term_time() const { return _term_time; } 1501 size_t term_attempts() const { return _term_attempts; } 1502 1503 private: 1504 inline bool offer_termination(); 1505 }; 1506 1507 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP