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 // Statistics for each allocation context 226 AllocationContextStats _allocation_context_stats; 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 == _update_allocation_context_stats_inc 281 // (f) cause == _wb_conc_mark 282 bool should_do_concurrent_full_gc(GCCause::Cause cause); 283 284 // indicates whether we are in young or mixed GC mode 285 G1CollectorState _collector_state; 286 287 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 288 // concurrent cycles) we have started. 289 volatile uint _old_marking_cycles_started; 290 291 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 292 // concurrent cycles) we have completed. 293 volatile uint _old_marking_cycles_completed; 294 295 // This is a non-product method that is helpful for testing. It is 296 // called at the end of a GC and artificially expands the heap by 297 // allocating a number of dead regions. This way we can induce very 298 // frequent marking cycles and stress the cleanup / concurrent 299 // cleanup code more (as all the regions that will be allocated by 300 // this method will be found dead by the marking cycle). 301 void allocate_dummy_regions() PRODUCT_RETURN; 302 303 // Clear RSets after a compaction. It also resets the GC time stamps. 304 void clear_rsets_post_compaction(); 305 306 // If the HR printer is active, dump the state of the regions in the 307 // heap after a compaction. 308 void print_hrm_post_compaction(); 309 310 // Create a memory mapper for auxiliary data structures of the given size and 311 // translation factor. 312 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 313 size_t size, 314 size_t translation_factor); 315 316 static G1Policy* create_g1_policy(STWGCTimer* gc_timer); 317 318 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 319 320 // These are macros so that, if the assert fires, we get the correct 321 // line number, file, etc. 322 323 #define heap_locking_asserts_params(_extra_message_) \ 324 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 325 (_extra_message_), \ 326 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 327 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 328 BOOL_TO_STR(Thread::current()->is_VM_thread()) 329 330 #define assert_heap_locked() \ 331 do { \ 332 assert(Heap_lock->owned_by_self(), \ 333 heap_locking_asserts_params("should be holding the Heap_lock")); \ 334 } while (0) 335 336 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 337 do { \ 338 assert(Heap_lock->owned_by_self() || \ 339 (SafepointSynchronize::is_at_safepoint() && \ 340 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 341 heap_locking_asserts_params("should be holding the Heap_lock or " \ 342 "should be at a safepoint")); \ 343 } while (0) 344 345 #define assert_heap_locked_and_not_at_safepoint() \ 346 do { \ 347 assert(Heap_lock->owned_by_self() && \ 348 !SafepointSynchronize::is_at_safepoint(), \ 349 heap_locking_asserts_params("should be holding the Heap_lock and " \ 350 "should not be at a safepoint")); \ 351 } while (0) 352 353 #define assert_heap_not_locked() \ 354 do { \ 355 assert(!Heap_lock->owned_by_self(), \ 356 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 357 } while (0) 358 359 #define assert_heap_not_locked_and_not_at_safepoint() \ 360 do { \ 361 assert(!Heap_lock->owned_by_self() && \ 362 !SafepointSynchronize::is_at_safepoint(), \ 363 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 364 "should not be at a safepoint")); \ 365 } while (0) 366 367 #define assert_at_safepoint(_should_be_vm_thread_) \ 368 do { \ 369 assert(SafepointSynchronize::is_at_safepoint() && \ 370 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 371 heap_locking_asserts_params("should be at a safepoint")); \ 372 } while (0) 373 374 #define assert_not_at_safepoint() \ 375 do { \ 376 assert(!SafepointSynchronize::is_at_safepoint(), \ 377 heap_locking_asserts_params("should not be at a safepoint")); \ 378 } while (0) 379 380 protected: 381 382 // The young region list. 383 G1EdenRegions _eden; 384 G1SurvivorRegions _survivor; 385 386 STWGCTimer* _gc_timer_stw; 387 388 G1NewTracer* _gc_tracer_stw; 389 390 // The current policy object for the collector. 391 G1Policy* _g1_policy; 392 G1HeapSizingPolicy* _heap_sizing_policy; 393 394 G1CollectionSet _collection_set; 395 396 // This is the second level of trying to allocate a new region. If 397 // new_region() didn't find a region on the free_list, this call will 398 // check whether there's anything available on the 399 // secondary_free_list and/or wait for more regions to appear on 400 // that list, if _free_regions_coming is set. 401 HeapRegion* new_region_try_secondary_free_list(bool is_old); 402 403 // Try to allocate a single non-humongous HeapRegion sufficient for 404 // an allocation of the given word_size. If do_expand is true, 405 // attempt to expand the heap if necessary to satisfy the allocation 406 // request. If the region is to be used as an old region or for a 407 // humongous object, set is_old to true. If not, to false. 408 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 409 410 // Initialize a contiguous set of free regions of length num_regions 411 // and starting at index first so that they appear as a single 412 // humongous region. 413 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 414 uint num_regions, 415 size_t word_size, 416 AllocationContext_t context); 417 418 // Attempt to allocate a humongous object of the given size. Return 419 // NULL if unsuccessful. 420 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 421 422 // The following two methods, allocate_new_tlab() and 423 // mem_allocate(), are the two main entry points from the runtime 424 // into the G1's allocation routines. They have the following 425 // assumptions: 426 // 427 // * They should both be called outside safepoints. 428 // 429 // * They should both be called without holding the Heap_lock. 430 // 431 // * All allocation requests for new TLABs should go to 432 // allocate_new_tlab(). 433 // 434 // * All non-TLAB allocation requests should go to mem_allocate(). 435 // 436 // * If either call cannot satisfy the allocation request using the 437 // current allocating region, they will try to get a new one. If 438 // this fails, they will attempt to do an evacuation pause and 439 // retry the allocation. 440 // 441 // * If all allocation attempts fail, even after trying to schedule 442 // an evacuation pause, allocate_new_tlab() will return NULL, 443 // whereas mem_allocate() will attempt a heap expansion and/or 444 // schedule a Full GC. 445 // 446 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 447 // should never be called with word_size being humongous. All 448 // humongous allocation requests should go to mem_allocate() which 449 // will satisfy them with a special path. 450 451 virtual HeapWord* allocate_new_tlab(size_t word_size); 452 453 virtual HeapWord* mem_allocate(size_t word_size, 454 bool* gc_overhead_limit_was_exceeded); 455 456 // First-level mutator allocation attempt: try to allocate out of 457 // the mutator alloc region without taking the Heap_lock. This 458 // should only be used for non-humongous allocations. 459 inline HeapWord* attempt_allocation(size_t word_size); 460 461 // Second-level mutator allocation attempt: take the Heap_lock and 462 // retry the allocation attempt, potentially scheduling a GC 463 // pause. This should only be used for non-humongous allocations. 464 HeapWord* attempt_allocation_slow(size_t word_size, 465 AllocationContext_t context); 466 467 // Takes the Heap_lock and attempts a humongous allocation. It can 468 // potentially schedule a GC pause. 469 HeapWord* attempt_allocation_humongous(size_t word_size); 470 471 // Allocation attempt that should be called during safepoints (e.g., 472 // at the end of a successful GC). expect_null_mutator_alloc_region 473 // specifies whether the mutator alloc region is expected to be NULL 474 // or not. 475 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 476 AllocationContext_t context, 477 bool expect_null_mutator_alloc_region); 478 479 // These methods are the "callbacks" from the G1AllocRegion class. 480 481 // For mutator alloc regions. 482 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 483 void retire_mutator_alloc_region(HeapRegion* alloc_region, 484 size_t allocated_bytes); 485 486 // For GC alloc regions. 487 bool has_more_regions(InCSetState dest); 488 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest); 489 void retire_gc_alloc_region(HeapRegion* alloc_region, 490 size_t allocated_bytes, InCSetState dest); 491 492 // - if explicit_gc is true, the GC is for a System.gc() etc, 493 // otherwise it's for a failed allocation. 494 // - if clear_all_soft_refs is true, all soft references should be 495 // cleared during the GC. 496 // - it returns false if it is unable to do the collection due to the 497 // GC locker being active, true otherwise. 498 bool do_full_collection(bool explicit_gc, 499 bool clear_all_soft_refs); 500 501 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 502 virtual void do_full_collection(bool clear_all_soft_refs); 503 504 // Resize the heap if necessary after a full collection. 505 void resize_if_necessary_after_full_collection(); 506 507 // Callback from VM_G1CollectForAllocation operation. 508 // This function does everything necessary/possible to satisfy a 509 // failed allocation request (including collection, expansion, etc.) 510 HeapWord* satisfy_failed_allocation(size_t word_size, 511 AllocationContext_t context, 512 bool* succeeded); 513 private: 514 // Internal helpers used during full GC to split it up to 515 // increase readability. 516 void abort_concurrent_cycle(); 517 void verify_before_full_collection(bool explicit_gc); 518 void prepare_heap_for_full_collection(); 519 void prepare_heap_for_mutators(); 520 void abort_refinement(); 521 void verify_after_full_collection(); 522 void print_heap_after_full_collection(G1HeapTransition* heap_transition); 523 524 // Helper method for satisfy_failed_allocation() 525 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 526 AllocationContext_t context, 527 bool do_gc, 528 bool clear_all_soft_refs, 529 bool expect_null_mutator_alloc_region, 530 bool* gc_succeeded); 531 532 protected: 533 // Attempting to expand the heap sufficiently 534 // to support an allocation of the given "word_size". If 535 // successful, perform the allocation and return the address of the 536 // allocated block, or else "NULL". 537 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 538 539 // Preserve any referents discovered by concurrent marking that have not yet been 540 // copied by the STW pause. 541 void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states); 542 // Process any reference objects discovered during 543 // an incremental evacuation pause. 544 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 545 546 // Enqueue any remaining discovered references 547 // after processing. 548 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states); 549 550 // Merges the information gathered on a per-thread basis for all worker threads 551 // during GC into global variables. 552 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states); 553 public: 554 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; } 555 556 WorkGang* workers() const { return _workers; } 557 558 G1Allocator* allocator() { 559 return _allocator; 560 } 561 562 G1HeapVerifier* verifier() { 563 return _verifier; 564 } 565 566 G1MonitoringSupport* g1mm() { 567 assert(_g1mm != NULL, "should have been initialized"); 568 return _g1mm; 569 } 570 571 // Expand the garbage-first heap by at least the given size (in bytes!). 572 // Returns true if the heap was expanded by the requested amount; 573 // false otherwise. 574 // (Rounds up to a HeapRegion boundary.) 575 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL); 576 577 // Returns the PLAB statistics for a given destination. 578 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 579 580 // Determines PLAB size for a given destination. 581 inline size_t desired_plab_sz(InCSetState dest); 582 583 inline AllocationContextStats& allocation_context_stats(); 584 585 // Do anything common to GC's. 586 void gc_prologue(bool full); 587 void gc_epilogue(bool full); 588 589 // Modify the reclaim candidate set and test for presence. 590 // These are only valid for starts_humongous regions. 591 inline void set_humongous_reclaim_candidate(uint region, bool value); 592 inline bool is_humongous_reclaim_candidate(uint region); 593 594 // Remove from the reclaim candidate set. Also remove from the 595 // collection set so that later encounters avoid the slow path. 596 inline void set_humongous_is_live(oop obj); 597 598 // Register the given region to be part of the collection set. 599 inline void register_humongous_region_with_cset(uint index); 600 // Register regions with humongous objects (actually on the start region) in 601 // the in_cset_fast_test table. 602 void register_humongous_regions_with_cset(); 603 // We register a region with the fast "in collection set" test. We 604 // simply set to true the array slot corresponding to this region. 605 void register_young_region_with_cset(HeapRegion* r) { 606 _in_cset_fast_test.set_in_young(r->hrm_index()); 607 } 608 void register_old_region_with_cset(HeapRegion* r) { 609 _in_cset_fast_test.set_in_old(r->hrm_index()); 610 } 611 inline void register_ext_region_with_cset(HeapRegion* r) { 612 _in_cset_fast_test.set_ext(r->hrm_index()); 613 } 614 void clear_in_cset(const HeapRegion* hr) { 615 _in_cset_fast_test.clear(hr); 616 } 617 618 void clear_cset_fast_test() { 619 _in_cset_fast_test.clear(); 620 } 621 622 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 623 624 // This is called at the start of either a concurrent cycle or a Full 625 // GC to update the number of old marking cycles started. 626 void increment_old_marking_cycles_started(); 627 628 // This is called at the end of either a concurrent cycle or a Full 629 // GC to update the number of old marking cycles completed. Those two 630 // can happen in a nested fashion, i.e., we start a concurrent 631 // cycle, a Full GC happens half-way through it which ends first, 632 // and then the cycle notices that a Full GC happened and ends 633 // too. The concurrent parameter is a boolean to help us do a bit 634 // tighter consistency checking in the method. If concurrent is 635 // false, the caller is the inner caller in the nesting (i.e., the 636 // Full GC). If concurrent is true, the caller is the outer caller 637 // in this nesting (i.e., the concurrent cycle). Further nesting is 638 // not currently supported. The end of this call also notifies 639 // the FullGCCount_lock in case a Java thread is waiting for a full 640 // GC to happen (e.g., it called System.gc() with 641 // +ExplicitGCInvokesConcurrent). 642 void increment_old_marking_cycles_completed(bool concurrent); 643 644 uint old_marking_cycles_completed() { 645 return _old_marking_cycles_completed; 646 } 647 648 G1HRPrinter* hr_printer() { return &_hr_printer; } 649 650 // Allocates a new heap region instance. 651 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 652 653 // Allocate the highest free region in the reserved heap. This will commit 654 // regions as necessary. 655 HeapRegion* alloc_highest_free_region(); 656 657 // Frees a non-humongous region by initializing its contents and 658 // adding it to the free list that's passed as a parameter (this is 659 // usually a local list which will be appended to the master free 660 // list later). The used bytes of freed regions are accumulated in 661 // pre_used. If skip_remset is true, the region's RSet will not be freed 662 // up. If skip_hot_card_cache is true, the region's hot card cache will not 663 // be freed up. The assumption is that this will be done later. 664 // The locked parameter indicates if the caller has already taken 665 // care of proper synchronization. This may allow some optimizations. 666 void free_region(HeapRegion* hr, 667 FreeRegionList* free_list, 668 bool skip_remset, 669 bool skip_hot_card_cache = false, 670 bool locked = false); 671 672 // It dirties the cards that cover the block so that the post 673 // write barrier never queues anything when updating objects on this 674 // block. It is assumed (and in fact we assert) that the block 675 // belongs to a young region. 676 inline void dirty_young_block(HeapWord* start, size_t word_size); 677 678 // Frees a humongous region by collapsing it into individual regions 679 // and calling free_region() for each of them. The freed regions 680 // will be added to the free list that's passed as a parameter (this 681 // is usually a local list which will be appended to the master free 682 // list later). The used bytes of freed regions are accumulated in 683 // pre_used. If skip_remset is true, the region's RSet will not be freed 684 // up. The assumption is that this will be done later. 685 void free_humongous_region(HeapRegion* hr, 686 FreeRegionList* free_list, 687 bool skip_remset); 688 689 // Facility for allocating in 'archive' regions in high heap memory and 690 // recording the allocated ranges. These should all be called from the 691 // VM thread at safepoints, without the heap lock held. They can be used 692 // to create and archive a set of heap regions which can be mapped at the 693 // same fixed addresses in a subsequent JVM invocation. 694 void begin_archive_alloc_range(bool open = false); 695 696 // Check if the requested size would be too large for an archive allocation. 697 bool is_archive_alloc_too_large(size_t word_size); 698 699 // Allocate memory of the requested size from the archive region. This will 700 // return NULL if the size is too large or if no memory is available. It 701 // does not trigger a garbage collection. 702 HeapWord* archive_mem_allocate(size_t word_size); 703 704 // Optionally aligns the end address and returns the allocated ranges in 705 // an array of MemRegions in order of ascending addresses. 706 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 707 size_t end_alignment_in_bytes = 0); 708 709 // Facility for allocating a fixed range within the heap and marking 710 // the containing regions as 'archive'. For use at JVM init time, when the 711 // caller may mmap archived heap data at the specified range(s). 712 // Verify that the MemRegions specified in the argument array are within the 713 // reserved heap. 714 bool check_archive_addresses(MemRegion* range, size_t count); 715 716 // Commit the appropriate G1 regions containing the specified MemRegions 717 // and mark them as 'archive' regions. The regions in the array must be 718 // non-overlapping and in order of ascending address. 719 bool alloc_archive_regions(MemRegion* range, size_t count, bool open); 720 721 // Insert any required filler objects in the G1 regions around the specified 722 // ranges to make the regions parseable. This must be called after 723 // alloc_archive_regions, and after class loading has occurred. 724 void fill_archive_regions(MemRegion* range, size_t count); 725 726 // For each of the specified MemRegions, uncommit the containing G1 regions 727 // which had been allocated by alloc_archive_regions. This should be called 728 // rather than fill_archive_regions at JVM init time if the archive file 729 // mapping failed, with the same non-overlapping and sorted MemRegion array. 730 void dealloc_archive_regions(MemRegion* range, size_t count); 731 732 protected: 733 734 // Shrink the garbage-first heap by at most the given size (in bytes!). 735 // (Rounds down to a HeapRegion boundary.) 736 virtual void shrink(size_t expand_bytes); 737 void shrink_helper(size_t expand_bytes); 738 739 #if TASKQUEUE_STATS 740 static void print_taskqueue_stats_hdr(outputStream* const st); 741 void print_taskqueue_stats() const; 742 void reset_taskqueue_stats(); 743 #endif // TASKQUEUE_STATS 744 745 // Schedule the VM operation that will do an evacuation pause to 746 // satisfy an allocation request of word_size. *succeeded will 747 // return whether the VM operation was successful (it did do an 748 // evacuation pause) or not (another thread beat us to it or the GC 749 // locker was active). Given that we should not be holding the 750 // Heap_lock when we enter this method, we will pass the 751 // gc_count_before (i.e., total_collections()) as a parameter since 752 // it has to be read while holding the Heap_lock. Currently, both 753 // methods that call do_collection_pause() release the Heap_lock 754 // before the call, so it's easy to read gc_count_before just before. 755 HeapWord* do_collection_pause(size_t word_size, 756 uint gc_count_before, 757 bool* succeeded, 758 GCCause::Cause gc_cause); 759 760 void wait_for_root_region_scanning(); 761 762 // The guts of the incremental collection pause, executed by the vm 763 // thread. It returns false if it is unable to do the collection due 764 // to the GC locker being active, true otherwise 765 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 766 767 // Actually do the work of evacuating the collection set. 768 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states); 769 770 void pre_evacuate_collection_set(); 771 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 772 773 // Print the header for the per-thread termination statistics. 774 static void print_termination_stats_hdr(); 775 // Print actual per-thread termination statistics. 776 void print_termination_stats(uint worker_id, 777 double elapsed_ms, 778 double strong_roots_ms, 779 double term_ms, 780 size_t term_attempts, 781 size_t alloc_buffer_waste, 782 size_t undo_waste) const; 783 // Update object copying statistics. 784 void record_obj_copy_mem_stats(); 785 786 // The hot card cache for remembered set insertion optimization. 787 G1HotCardCache* _hot_card_cache; 788 789 // The g1 remembered set of the heap. 790 G1RemSet* _g1_rem_set; 791 792 // A set of cards that cover the objects for which the Rsets should be updated 793 // concurrently after the collection. 794 DirtyCardQueueSet _dirty_card_queue_set; 795 796 // After a collection pause, convert the regions in the collection set into free 797 // regions. 798 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 799 800 // Abandon the current collection set without recording policy 801 // statistics or updating free lists. 802 void abandon_collection_set(G1CollectionSet* collection_set); 803 804 // The concurrent marker (and the thread it runs in.) 805 G1ConcurrentMark* _cm; 806 ConcurrentMarkThread* _cmThread; 807 808 // The concurrent refiner. 809 G1ConcurrentRefine* _cr; 810 811 // The parallel task queues 812 RefToScanQueueSet *_task_queues; 813 814 // True iff a evacuation has failed in the current collection. 815 bool _evacuation_failed; 816 817 EvacuationFailedInfo* _evacuation_failed_info_array; 818 819 // Failed evacuations cause some logical from-space objects to have 820 // forwarding pointers to themselves. Reset them. 821 void remove_self_forwarding_pointers(); 822 823 // Restore the objects in the regions in the collection set after an 824 // evacuation failure. 825 void restore_after_evac_failure(); 826 827 PreservedMarksSet _preserved_marks_set; 828 829 // Preserve the mark of "obj", if necessary, in preparation for its mark 830 // word being overwritten with a self-forwarding-pointer. 831 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 832 833 #ifndef PRODUCT 834 // Support for forcing evacuation failures. Analogous to 835 // PromotionFailureALot for the other collectors. 836 837 // Records whether G1EvacuationFailureALot should be in effect 838 // for the current GC 839 bool _evacuation_failure_alot_for_current_gc; 840 841 // Used to record the GC number for interval checking when 842 // determining whether G1EvaucationFailureALot is in effect 843 // for the current GC. 844 size_t _evacuation_failure_alot_gc_number; 845 846 // Count of the number of evacuations between failures. 847 volatile size_t _evacuation_failure_alot_count; 848 849 // Set whether G1EvacuationFailureALot should be in effect 850 // for the current GC (based upon the type of GC and which 851 // command line flags are set); 852 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 853 bool during_initial_mark, 854 bool during_marking); 855 856 inline void set_evacuation_failure_alot_for_current_gc(); 857 858 // Return true if it's time to cause an evacuation failure. 859 inline bool evacuation_should_fail(); 860 861 // Reset the G1EvacuationFailureALot counters. Should be called at 862 // the end of an evacuation pause in which an evacuation failure occurred. 863 inline void reset_evacuation_should_fail(); 864 #endif // !PRODUCT 865 866 // ("Weak") Reference processing support. 867 // 868 // G1 has 2 instances of the reference processor class. One 869 // (_ref_processor_cm) handles reference object discovery 870 // and subsequent processing during concurrent marking cycles. 871 // 872 // The other (_ref_processor_stw) handles reference object 873 // discovery and processing during full GCs and incremental 874 // evacuation pauses. 875 // 876 // During an incremental pause, reference discovery will be 877 // temporarily disabled for _ref_processor_cm and will be 878 // enabled for _ref_processor_stw. At the end of the evacuation 879 // pause references discovered by _ref_processor_stw will be 880 // processed and discovery will be disabled. The previous 881 // setting for reference object discovery for _ref_processor_cm 882 // will be re-instated. 883 // 884 // At the start of marking: 885 // * Discovery by the CM ref processor is verified to be inactive 886 // and it's discovered lists are empty. 887 // * Discovery by the CM ref processor is then enabled. 888 // 889 // At the end of marking: 890 // * Any references on the CM ref processor's discovered 891 // lists are processed (possibly MT). 892 // 893 // At the start of full GC we: 894 // * Disable discovery by the CM ref processor and 895 // empty CM ref processor's discovered lists 896 // (without processing any entries). 897 // * Verify that the STW ref processor is inactive and it's 898 // discovered lists are empty. 899 // * Temporarily set STW ref processor discovery as single threaded. 900 // * Temporarily clear the STW ref processor's _is_alive_non_header 901 // field. 902 // * Finally enable discovery by the STW ref processor. 903 // 904 // The STW ref processor is used to record any discovered 905 // references during the full GC. 906 // 907 // At the end of a full GC we: 908 // * Enqueue any reference objects discovered by the STW ref processor 909 // that have non-live referents. This has the side-effect of 910 // making the STW ref processor inactive by disabling discovery. 911 // * Verify that the CM ref processor is still inactive 912 // and no references have been placed on it's discovered 913 // lists (also checked as a precondition during initial marking). 914 915 // The (stw) reference processor... 916 ReferenceProcessor* _ref_processor_stw; 917 918 // During reference object discovery, the _is_alive_non_header 919 // closure (if non-null) is applied to the referent object to 920 // determine whether the referent is live. If so then the 921 // reference object does not need to be 'discovered' and can 922 // be treated as a regular oop. This has the benefit of reducing 923 // the number of 'discovered' reference objects that need to 924 // be processed. 925 // 926 // Instance of the is_alive closure for embedding into the 927 // STW reference processor as the _is_alive_non_header field. 928 // Supplying a value for the _is_alive_non_header field is 929 // optional but doing so prevents unnecessary additions to 930 // the discovered lists during reference discovery. 931 G1STWIsAliveClosure _is_alive_closure_stw; 932 933 // The (concurrent marking) reference processor... 934 ReferenceProcessor* _ref_processor_cm; 935 936 // Instance of the concurrent mark is_alive closure for embedding 937 // into the Concurrent Marking reference processor as the 938 // _is_alive_non_header field. Supplying a value for the 939 // _is_alive_non_header field is optional but doing so prevents 940 // unnecessary additions to the discovered lists during reference 941 // discovery. 942 G1CMIsAliveClosure _is_alive_closure_cm; 943 944 volatile bool _free_regions_coming; 945 946 public: 947 948 RefToScanQueue *task_queue(uint i) const; 949 950 uint num_task_queues() const; 951 952 // A set of cards where updates happened during the GC 953 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 954 955 // Create a G1CollectedHeap with the specified policy. 956 // Must call the initialize method afterwards. 957 // May not return if something goes wrong. 958 G1CollectedHeap(G1CollectorPolicy* policy); 959 960 private: 961 jint initialize_concurrent_refinement(); 962 jint initialize_young_gen_sampling_thread(); 963 public: 964 // Initialize the G1CollectedHeap to have the initial and 965 // maximum sizes and remembered and barrier sets 966 // specified by the policy object. 967 jint initialize(); 968 969 virtual void stop(); 970 virtual void safepoint_synchronize_begin(); 971 virtual void safepoint_synchronize_end(); 972 973 // Return the (conservative) maximum heap alignment for any G1 heap 974 static size_t conservative_max_heap_alignment(); 975 976 // Does operations required after initialization has been done. 977 void post_initialize(); 978 979 // Initialize weak reference processing. 980 void ref_processing_init(); 981 982 virtual Name kind() const { 983 return CollectedHeap::G1CollectedHeap; 984 } 985 986 virtual const char* name() const { 987 return "G1"; 988 } 989 990 const G1CollectorState* collector_state() const { return &_collector_state; } 991 G1CollectorState* collector_state() { return &_collector_state; } 992 993 // The current policy object for the collector. 994 G1Policy* g1_policy() const { return _g1_policy; } 995 996 const G1CollectionSet* collection_set() const { return &_collection_set; } 997 G1CollectionSet* collection_set() { return &_collection_set; } 998 999 virtual CollectorPolicy* collector_policy() const; 1000 1001 // Adaptive size policy. No such thing for g1. 1002 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1003 1004 virtual GrowableArray<GCMemoryManager*> memory_managers(); 1005 virtual GrowableArray<MemoryPool*> memory_pools(); 1006 1007 // The rem set and barrier set. 1008 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1009 1010 // Try to minimize the remembered set. 1011 void scrub_rem_set(); 1012 1013 uint get_gc_time_stamp() { 1014 return _gc_time_stamp; 1015 } 1016 1017 inline void reset_gc_time_stamp(); 1018 1019 void check_gc_time_stamps() PRODUCT_RETURN; 1020 1021 inline void increment_gc_time_stamp(); 1022 1023 // Reset the given region's GC timestamp. If it's starts humongous, 1024 // also reset the GC timestamp of its corresponding 1025 // continues humongous regions too. 1026 void reset_gc_time_stamps(HeapRegion* hr); 1027 1028 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 1029 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i); 1030 1031 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. 1032 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i); 1033 1034 // The shared block offset table array. 1035 G1BlockOffsetTable* bot() const { return _bot; } 1036 1037 // Reference Processing accessors 1038 1039 // The STW reference processor.... 1040 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1041 1042 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1043 1044 // The Concurrent Marking reference processor... 1045 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1046 1047 size_t unused_committed_regions_in_bytes() const; 1048 virtual size_t capacity() const; 1049 virtual size_t used() const; 1050 // This should be called when we're not holding the heap lock. The 1051 // result might be a bit inaccurate. 1052 size_t used_unlocked() const; 1053 size_t recalculate_used() const; 1054 1055 // These virtual functions do the actual allocation. 1056 // Some heaps may offer a contiguous region for shared non-blocking 1057 // allocation, via inlined code (by exporting the address of the top and 1058 // end fields defining the extent of the contiguous allocation region.) 1059 // But G1CollectedHeap doesn't yet support this. 1060 1061 virtual bool is_maximal_no_gc() const { 1062 return _hrm.available() == 0; 1063 } 1064 1065 // Returns whether there are any regions left in the heap for allocation. 1066 bool has_regions_left_for_allocation() const { 1067 return !is_maximal_no_gc() || num_free_regions() != 0; 1068 } 1069 1070 // The current number of regions in the heap. 1071 uint num_regions() const { return _hrm.length(); } 1072 1073 // The max number of regions in the heap. 1074 uint max_regions() const { return _hrm.max_length(); } 1075 1076 // The number of regions that are completely free. 1077 uint num_free_regions() const { return _hrm.num_free_regions(); } 1078 1079 MemoryUsage get_auxiliary_data_memory_usage() const { 1080 return _hrm.get_auxiliary_data_memory_usage(); 1081 } 1082 1083 // The number of regions that are not completely free. 1084 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1085 1086 #ifdef ASSERT 1087 bool is_on_master_free_list(HeapRegion* hr) { 1088 return _hrm.is_free(hr); 1089 } 1090 #endif // ASSERT 1091 1092 // Wrapper for the region list operations that can be called from 1093 // methods outside this class. 1094 1095 void secondary_free_list_add(FreeRegionList* list) { 1096 _secondary_free_list.add_ordered(list); 1097 } 1098 1099 void append_secondary_free_list() { 1100 _hrm.insert_list_into_free_list(&_secondary_free_list); 1101 } 1102 1103 void append_secondary_free_list_if_not_empty_with_lock() { 1104 // If the secondary free list looks empty there's no reason to 1105 // take the lock and then try to append it. 1106 if (!_secondary_free_list.is_empty()) { 1107 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1108 append_secondary_free_list(); 1109 } 1110 } 1111 1112 inline void old_set_add(HeapRegion* hr); 1113 inline void old_set_remove(HeapRegion* hr); 1114 1115 size_t non_young_capacity_bytes() { 1116 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes; 1117 } 1118 1119 void set_free_regions_coming(); 1120 void reset_free_regions_coming(); 1121 bool free_regions_coming() { return _free_regions_coming; } 1122 void wait_while_free_regions_coming(); 1123 1124 // Determine whether the given region is one that we are using as an 1125 // old GC alloc region. 1126 bool is_old_gc_alloc_region(HeapRegion* hr); 1127 1128 // Perform a collection of the heap; intended for use in implementing 1129 // "System.gc". This probably implies as full a collection as the 1130 // "CollectedHeap" supports. 1131 virtual void collect(GCCause::Cause cause); 1132 1133 virtual bool copy_allocation_context_stats(const jint* contexts, 1134 jlong* totals, 1135 jbyte* accuracy, 1136 jint len); 1137 1138 // True iff an evacuation has failed in the most-recent collection. 1139 bool evacuation_failed() { return _evacuation_failed; } 1140 1141 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed); 1142 void prepend_to_freelist(FreeRegionList* list); 1143 void decrement_summary_bytes(size_t bytes); 1144 1145 virtual bool is_in(const void* p) const; 1146 #ifdef ASSERT 1147 // Returns whether p is in one of the available areas of the heap. Slow but 1148 // extensive version. 1149 bool is_in_exact(const void* p) const; 1150 #endif 1151 1152 // Return "TRUE" iff the given object address is within the collection 1153 // set. Assumes that the reference points into the heap. 1154 inline bool is_in_cset(const HeapRegion *hr); 1155 inline bool is_in_cset(oop obj); 1156 inline bool is_in_cset(HeapWord* addr); 1157 1158 inline bool is_in_cset_or_humongous(const oop obj); 1159 1160 private: 1161 // This array is used for a quick test on whether a reference points into 1162 // the collection set or not. Each of the array's elements denotes whether the 1163 // corresponding region is in the collection set or not. 1164 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1165 1166 public: 1167 1168 inline InCSetState in_cset_state(const oop obj); 1169 1170 // Return "TRUE" iff the given object address is in the reserved 1171 // region of g1. 1172 bool is_in_g1_reserved(const void* p) const { 1173 return _hrm.reserved().contains(p); 1174 } 1175 1176 // Returns a MemRegion that corresponds to the space that has been 1177 // reserved for the heap 1178 MemRegion g1_reserved() const { 1179 return _hrm.reserved(); 1180 } 1181 1182 virtual bool is_in_closed_subset(const void* p) const; 1183 1184 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1185 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set()); 1186 } 1187 1188 G1HotCardCache* g1_hot_card_cache() const { return _hot_card_cache; } 1189 1190 // Iteration functions. 1191 1192 // Iterate over all objects, calling "cl.do_object" on each. 1193 virtual void object_iterate(ObjectClosure* cl); 1194 1195 virtual void safe_object_iterate(ObjectClosure* cl) { 1196 object_iterate(cl); 1197 } 1198 1199 // Iterate over heap regions, in address order, terminating the 1200 // iteration early if the "doHeapRegion" method returns "true". 1201 void heap_region_iterate(HeapRegionClosure* blk) const; 1202 1203 // Return the region with the given index. It assumes the index is valid. 1204 inline HeapRegion* region_at(uint index) const; 1205 1206 // Return the next region (by index) that is part of the same 1207 // humongous object that hr is part of. 1208 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1209 1210 // Calculate the region index of the given address. Given address must be 1211 // within the heap. 1212 inline uint addr_to_region(HeapWord* addr) const; 1213 1214 inline HeapWord* bottom_addr_for_region(uint index) const; 1215 1216 // Two functions to iterate over the heap regions in parallel. Threads 1217 // compete using the HeapRegionClaimer to claim the regions before 1218 // applying the closure on them. 1219 // The _from_worker_offset version uses the HeapRegionClaimer and 1220 // the worker id to calculate a start offset to prevent all workers to 1221 // start from the point. 1222 void heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl, 1223 HeapRegionClaimer* hrclaimer, 1224 uint worker_id) const; 1225 1226 void heap_region_par_iterate_from_start(HeapRegionClosure* cl, 1227 HeapRegionClaimer* hrclaimer) const; 1228 1229 // Iterate over the regions (if any) in the current collection set. 1230 void collection_set_iterate(HeapRegionClosure* blk); 1231 1232 // Iterate over the regions (if any) in the current collection set. Starts the 1233 // iteration over the entire collection set so that the start regions of a given 1234 // worker id over the set active_workers are evenly spread across the set of 1235 // collection set regions. 1236 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id); 1237 1238 // Returns the HeapRegion that contains addr. addr must not be NULL. 1239 template <class T> 1240 inline HeapRegion* heap_region_containing(const T addr) const; 1241 1242 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1243 // each address in the (reserved) heap is a member of exactly 1244 // one block. The defining characteristic of a block is that it is 1245 // possible to find its size, and thus to progress forward to the next 1246 // block. (Blocks may be of different sizes.) Thus, blocks may 1247 // represent Java objects, or they might be free blocks in a 1248 // free-list-based heap (or subheap), as long as the two kinds are 1249 // distinguishable and the size of each is determinable. 1250 1251 // Returns the address of the start of the "block" that contains the 1252 // address "addr". We say "blocks" instead of "object" since some heaps 1253 // may not pack objects densely; a chunk may either be an object or a 1254 // non-object. 1255 virtual HeapWord* block_start(const void* addr) const; 1256 1257 // Requires "addr" to be the start of a chunk, and returns its size. 1258 // "addr + size" is required to be the start of a new chunk, or the end 1259 // of the active area of the heap. 1260 virtual size_t block_size(const HeapWord* addr) const; 1261 1262 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1263 // the block is an object. 1264 virtual bool block_is_obj(const HeapWord* addr) const; 1265 1266 // Section on thread-local allocation buffers (TLABs) 1267 // See CollectedHeap for semantics. 1268 1269 bool supports_tlab_allocation() const; 1270 size_t tlab_capacity(Thread* ignored) const; 1271 size_t tlab_used(Thread* ignored) const; 1272 size_t max_tlab_size() const; 1273 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1274 1275 // Can a compiler initialize a new object without store barriers? 1276 // This permission only extends from the creation of a new object 1277 // via a TLAB up to the first subsequent safepoint. If such permission 1278 // is granted for this heap type, the compiler promises to call 1279 // defer_store_barrier() below on any slow path allocation of 1280 // a new object for which such initializing store barriers will 1281 // have been elided. G1, like CMS, allows this, but should be 1282 // ready to provide a compensating write barrier as necessary 1283 // if that storage came out of a non-young region. The efficiency 1284 // of this implementation depends crucially on being able to 1285 // answer very efficiently in constant time whether a piece of 1286 // storage in the heap comes from a young region or not. 1287 // See ReduceInitialCardMarks. 1288 virtual bool can_elide_tlab_store_barriers() const { 1289 return true; 1290 } 1291 1292 virtual bool card_mark_must_follow_store() const { 1293 return true; 1294 } 1295 1296 inline bool is_in_young(const oop obj); 1297 1298 // We don't need barriers for initializing stores to objects 1299 // in the young gen: for the SATB pre-barrier, there is no 1300 // pre-value that needs to be remembered; for the remembered-set 1301 // update logging post-barrier, we don't maintain remembered set 1302 // information for young gen objects. 1303 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1304 1305 // Returns "true" iff the given word_size is "very large". 1306 static bool is_humongous(size_t word_size) { 1307 // Note this has to be strictly greater-than as the TLABs 1308 // are capped at the humongous threshold and we want to 1309 // ensure that we don't try to allocate a TLAB as 1310 // humongous and that we don't allocate a humongous 1311 // object in a TLAB. 1312 return word_size > _humongous_object_threshold_in_words; 1313 } 1314 1315 // Returns the humongous threshold for a specific region size 1316 static size_t humongous_threshold_for(size_t region_size) { 1317 return (region_size / 2); 1318 } 1319 1320 // Returns the number of regions the humongous object of the given word size 1321 // requires. 1322 static size_t humongous_obj_size_in_regions(size_t word_size); 1323 1324 // Print the maximum heap capacity. 1325 virtual size_t max_capacity() const; 1326 1327 virtual jlong millis_since_last_gc(); 1328 1329 1330 // Convenience function to be used in situations where the heap type can be 1331 // asserted to be this type. 1332 static G1CollectedHeap* heap(); 1333 1334 void set_region_short_lived_locked(HeapRegion* hr); 1335 // add appropriate methods for any other surv rate groups 1336 1337 const G1SurvivorRegions* survivor() const { return &_survivor; } 1338 1339 uint survivor_regions_count() const { 1340 return _survivor.length(); 1341 } 1342 1343 uint eden_regions_count() const { 1344 return _eden.length(); 1345 } 1346 1347 uint young_regions_count() const { 1348 return _eden.length() + _survivor.length(); 1349 } 1350 1351 uint old_regions_count() const { return _old_set.length(); } 1352 1353 uint humongous_regions_count() const { return _humongous_set.length(); } 1354 1355 #ifdef ASSERT 1356 bool check_young_list_empty(); 1357 #endif 1358 1359 // *** Stuff related to concurrent marking. It's not clear to me that so 1360 // many of these need to be public. 1361 1362 // The functions below are helper functions that a subclass of 1363 // "CollectedHeap" can use in the implementation of its virtual 1364 // functions. 1365 // This performs a concurrent marking of the live objects in a 1366 // bitmap off to the side. 1367 void doConcurrentMark(); 1368 1369 bool isMarkedNext(oop obj) const; 1370 1371 // Determine if an object is dead, given the object and also 1372 // the region to which the object belongs. An object is dead 1373 // iff a) it was not allocated since the last mark, b) it 1374 // is not marked, and c) it is not in an archive region. 1375 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1376 return 1377 hr->is_obj_dead(obj, _cm->prev_mark_bitmap()) && 1378 !hr->is_archive(); 1379 } 1380 1381 // This function returns true when an object has been 1382 // around since the previous marking and hasn't yet 1383 // been marked during this marking, and is not in an archive region. 1384 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1385 return 1386 !hr->obj_allocated_since_next_marking(obj) && 1387 !isMarkedNext(obj) && 1388 !hr->is_archive(); 1389 } 1390 1391 // Determine if an object is dead, given only the object itself. 1392 // This will find the region to which the object belongs and 1393 // then call the region version of the same function. 1394 1395 // Added if it is NULL it isn't dead. 1396 1397 inline bool is_obj_dead(const oop obj) const; 1398 1399 inline bool is_obj_ill(const oop obj) const; 1400 1401 inline bool is_obj_dead_full(const oop obj, const HeapRegion* hr) const; 1402 inline bool is_obj_dead_full(const oop obj) const; 1403 1404 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1405 1406 // Refinement 1407 1408 G1ConcurrentRefine* concurrent_refine() const { return _cr; } 1409 1410 // Optimized nmethod scanning support routines 1411 1412 // Is an oop scavengeable 1413 virtual bool is_scavengable(oop obj); 1414 1415 // Register the given nmethod with the G1 heap. 1416 virtual void register_nmethod(nmethod* nm); 1417 1418 // Unregister the given nmethod from the G1 heap. 1419 virtual void unregister_nmethod(nmethod* nm); 1420 1421 // Free up superfluous code root memory. 1422 void purge_code_root_memory(); 1423 1424 // Rebuild the strong code root lists for each region 1425 // after a full GC. 1426 void rebuild_strong_code_roots(); 1427 1428 // Partial cleaning used when class unloading is disabled. 1429 // Let the caller choose what structures to clean out: 1430 // - StringTable 1431 // - SymbolTable 1432 // - StringDeduplication structures 1433 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup); 1434 1435 // Complete cleaning used when class unloading is enabled. 1436 // Cleans out all structures handled by partial_cleaning and also the CodeCache. 1437 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); 1438 1439 // Redirty logged cards in the refinement queue. 1440 void redirty_logged_cards(); 1441 // Verification 1442 1443 // Perform any cleanup actions necessary before allowing a verification. 1444 virtual void prepare_for_verify(); 1445 1446 // Perform verification. 1447 1448 // vo == UsePrevMarking -> use "prev" marking information, 1449 // vo == UseNextMarking -> use "next" marking information 1450 // vo == UseFullMarking -> use "next" marking bitmap but no TAMS 1451 // 1452 // NOTE: Only the "prev" marking information is guaranteed to be 1453 // consistent most of the time, so most calls to this should use 1454 // vo == UsePrevMarking. 1455 // Currently, there is only one case where this is called with 1456 // vo == UseNextMarking, which is to verify the "next" marking 1457 // information at the end of remark. 1458 // Currently there is only one place where this is called with 1459 // vo == UseFullMarking, which is to verify the marking during a 1460 // full GC. 1461 void verify(VerifyOption vo); 1462 1463 // WhiteBox testing support. 1464 virtual bool supports_concurrent_phase_control() const; 1465 virtual const char* const* concurrent_phases() const; 1466 virtual bool request_concurrent_phase(const char* phase); 1467 1468 // The methods below are here for convenience and dispatch the 1469 // appropriate method depending on value of the given VerifyOption 1470 // parameter. The values for that parameter, and their meanings, 1471 // are the same as those above. 1472 1473 bool is_obj_dead_cond(const oop obj, 1474 const HeapRegion* hr, 1475 const VerifyOption vo) const; 1476 1477 bool is_obj_dead_cond(const oop obj, 1478 const VerifyOption vo) const; 1479 1480 G1HeapSummary create_g1_heap_summary(); 1481 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1482 1483 // Printing 1484 private: 1485 void print_heap_regions() const; 1486 void print_regions_on(outputStream* st) const; 1487 1488 public: 1489 virtual void print_on(outputStream* st) const; 1490 virtual void print_extended_on(outputStream* st) const; 1491 virtual void print_on_error(outputStream* st) const; 1492 1493 virtual void print_gc_threads_on(outputStream* st) const; 1494 virtual void gc_threads_do(ThreadClosure* tc) const; 1495 1496 // Override 1497 void print_tracing_info() const; 1498 1499 // The following two methods are helpful for debugging RSet issues. 1500 void print_cset_rsets() PRODUCT_RETURN; 1501 void print_all_rsets() PRODUCT_RETURN; 1502 1503 public: 1504 size_t pending_card_num(); 1505 1506 protected: 1507 size_t _max_heap_capacity; 1508 }; 1509 1510 class G1ParEvacuateFollowersClosure : public VoidClosure { 1511 private: 1512 double _start_term; 1513 double _term_time; 1514 size_t _term_attempts; 1515 1516 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 1517 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 1518 protected: 1519 G1CollectedHeap* _g1h; 1520 G1ParScanThreadState* _par_scan_state; 1521 RefToScanQueueSet* _queues; 1522 ParallelTaskTerminator* _terminator; 1523 1524 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 1525 RefToScanQueueSet* queues() { return _queues; } 1526 ParallelTaskTerminator* terminator() { return _terminator; } 1527 1528 public: 1529 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 1530 G1ParScanThreadState* par_scan_state, 1531 RefToScanQueueSet* queues, 1532 ParallelTaskTerminator* terminator) 1533 : _g1h(g1h), _par_scan_state(par_scan_state), 1534 _queues(queues), _terminator(terminator), 1535 _start_term(0.0), _term_time(0.0), _term_attempts(0) {} 1536 1537 void do_void(); 1538 1539 double term_time() const { return _term_time; } 1540 size_t term_attempts() const { return _term_attempts; } 1541 1542 private: 1543 inline bool offer_termination(); 1544 }; 1545 1546 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP