1 /* 2 * Copyright (c) 2001, 2017, 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 "utilities/stack.hpp" 54 55 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 56 // It uses the "Garbage First" heap organization and algorithm, which 57 // may combine concurrent marking with parallel, incremental compaction of 58 // heap subsets that will yield large amounts of garbage. 59 60 // Forward declarations 61 class HeapRegion; 62 class HRRSCleanupTask; 63 class GenerationSpec; 64 class G1ParScanThreadState; 65 class G1ParScanThreadStateSet; 66 class G1ParScanThreadState; 67 class ObjectClosure; 68 class SpaceClosure; 69 class CompactibleSpaceClosure; 70 class Space; 71 class G1CollectionSet; 72 class G1CollectorPolicy; 73 class G1Policy; 74 class G1HotCardCache; 75 class G1RemSet; 76 class G1YoungRemSetSamplingThread; 77 class HeapRegionRemSetIterator; 78 class G1ConcurrentMark; 79 class ConcurrentMarkThread; 80 class G1ConcurrentRefine; 81 class GenerationCounters; 82 class STWGCTimer; 83 class G1NewTracer; 84 class EvacuationFailedInfo; 85 class nmethod; 86 class Ticks; 87 class WorkGang; 88 class G1Allocator; 89 class G1ArchiveAllocator; 90 class G1FullGCScope; 91 class G1HeapVerifier; 92 class G1HeapSizingPolicy; 93 class G1HeapSummary; 94 class G1EvacSummary; 95 96 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 97 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 98 99 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 100 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 101 102 // The G1 STW is alive closure. 103 // An instance is embedded into the G1CH and used as the 104 // (optional) _is_alive_non_header closure in the STW 105 // reference processor. It is also extensively used during 106 // reference processing during STW evacuation pauses. 107 class G1STWIsAliveClosure: public BoolObjectClosure { 108 G1CollectedHeap* _g1; 109 public: 110 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 111 bool do_object_b(oop p); 112 }; 113 114 class G1RegionMappingChangedListener : public G1MappingChangedListener { 115 private: 116 void reset_from_card_cache(uint start_idx, size_t num_regions); 117 public: 118 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 119 }; 120 121 class G1CollectedHeap : public CollectedHeap { 122 friend class G1FreeCollectionSetTask; 123 friend class VM_CollectForMetadataAllocation; 124 friend class VM_G1CollectForAllocation; 125 friend class VM_G1CollectFull; 126 friend class VM_G1IncCollectionPause; 127 friend class VMStructs; 128 friend class MutatorAllocRegion; 129 friend class G1FullCollector; 130 friend class G1GCAllocRegion; 131 friend class G1HeapVerifier; 132 133 // Closures used in implementation. 134 friend class G1ParScanThreadState; 135 friend class G1ParScanThreadStateSet; 136 friend class G1ParTask; 137 friend class G1PLABAllocator; 138 friend class G1PrepareCompactClosure; 139 140 // Other related classes. 141 friend class HeapRegionClaimer; 142 143 // Testing classes. 144 friend class G1CheckCSetFastTableClosure; 145 146 private: 147 G1YoungRemSetSamplingThread* _young_gen_sampling_thread; 148 149 WorkGang* _workers; 150 G1CollectorPolicy* _collector_policy; 151 152 static size_t _humongous_object_threshold_in_words; 153 154 // The secondary free list which contains regions that have been 155 // freed up during the cleanup process. This will be appended to 156 // the master free list when appropriate. 157 FreeRegionList _secondary_free_list; 158 159 // It keeps track of the old regions. 160 HeapRegionSet _old_set; 161 162 // It keeps track of the humongous regions. 163 HeapRegionSet _humongous_set; 164 165 void eagerly_reclaim_humongous_regions(); 166 // Start a new incremental collection set for the next pause. 167 void start_new_collection_set(); 168 169 // The number of regions we could create by expansion. 170 uint _expansion_regions; 171 172 // The block offset table for the G1 heap. 173 G1BlockOffsetTable* _bot; 174 175 // Tears down the region sets / lists so that they are empty and the 176 // regions on the heap do not belong to a region set / list. The 177 // only exception is the humongous set which we leave unaltered. If 178 // free_list_only is true, it will only tear down the master free 179 // list. It is called before a Full GC (free_list_only == false) or 180 // before heap shrinking (free_list_only == true). 181 void tear_down_region_sets(bool free_list_only); 182 183 // Rebuilds the region sets / lists so that they are repopulated to 184 // reflect the contents of the heap. The only exception is the 185 // humongous set which was not torn down in the first place. If 186 // free_list_only is true, it will only rebuild the master free 187 // list. It is called after a Full GC (free_list_only == false) or 188 // after heap shrinking (free_list_only == true). 189 void rebuild_region_sets(bool free_list_only); 190 191 // Callback for region mapping changed events. 192 G1RegionMappingChangedListener _listener; 193 194 // The sequence of all heap regions in the heap. 195 HeapRegionManager _hrm; 196 197 // Manages all allocations with regions except humongous object allocations. 198 G1Allocator* _allocator; 199 200 // Manages all heap verification. 201 G1HeapVerifier* _verifier; 202 203 // Outside of GC pauses, the number of bytes used in all regions other 204 // than the current allocation region(s). 205 size_t _summary_bytes_used; 206 207 void increase_used(size_t bytes); 208 void decrease_used(size_t bytes); 209 210 void set_used(size_t bytes); 211 212 // Class that handles archive allocation ranges. 213 G1ArchiveAllocator* _archive_allocator; 214 215 // Statistics for each allocation context 216 AllocationContextStats _allocation_context_stats; 217 218 // GC allocation statistics policy for survivors. 219 G1EvacStats _survivor_evac_stats; 220 221 // GC allocation statistics policy for tenured objects. 222 G1EvacStats _old_evac_stats; 223 224 // It specifies whether we should attempt to expand the heap after a 225 // region allocation failure. If heap expansion fails we set this to 226 // false so that we don't re-attempt the heap expansion (it's likely 227 // that subsequent expansion attempts will also fail if one fails). 228 // Currently, it is only consulted during GC and it's reset at the 229 // start of each GC. 230 bool _expand_heap_after_alloc_failure; 231 232 // Helper for monitoring and management support. 233 G1MonitoringSupport* _g1mm; 234 235 // Records whether the region at the given index is (still) a 236 // candidate for eager reclaim. Only valid for humongous start 237 // regions; other regions have unspecified values. Humongous start 238 // regions are initialized at start of collection pause, with 239 // candidates removed from the set as they are found reachable from 240 // roots or the young generation. 241 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 242 protected: 243 bool default_value() const { return false; } 244 public: 245 void clear() { G1BiasedMappedArray<bool>::clear(); } 246 void set_candidate(uint region, bool value) { 247 set_by_index(region, value); 248 } 249 bool is_candidate(uint region) { 250 return get_by_index(region); 251 } 252 }; 253 254 HumongousReclaimCandidates _humongous_reclaim_candidates; 255 // Stores whether during humongous object registration we found candidate regions. 256 // If not, we can skip a few steps. 257 bool _has_humongous_reclaim_candidates; 258 259 volatile uint _gc_time_stamp; 260 261 G1HRPrinter _hr_printer; 262 263 // It decides whether an explicit GC should start a concurrent cycle 264 // instead of doing a STW GC. Currently, a concurrent cycle is 265 // explicitly started if: 266 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 267 // (b) cause == _g1_humongous_allocation 268 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 269 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 270 // (e) cause == _update_allocation_context_stats_inc 271 // (f) cause == _wb_conc_mark 272 bool should_do_concurrent_full_gc(GCCause::Cause cause); 273 274 // indicates whether we are in young or mixed GC mode 275 G1CollectorState _collector_state; 276 277 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 278 // concurrent cycles) we have started. 279 volatile uint _old_marking_cycles_started; 280 281 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 282 // concurrent cycles) we have completed. 283 volatile uint _old_marking_cycles_completed; 284 285 // This is a non-product method that is helpful for testing. It is 286 // called at the end of a GC and artificially expands the heap by 287 // allocating a number of dead regions. This way we can induce very 288 // frequent marking cycles and stress the cleanup / concurrent 289 // cleanup code more (as all the regions that will be allocated by 290 // this method will be found dead by the marking cycle). 291 void allocate_dummy_regions() PRODUCT_RETURN; 292 293 // Clear RSets after a compaction. It also resets the GC time stamps. 294 void clear_rsets_post_compaction(); 295 296 // If the HR printer is active, dump the state of the regions in the 297 // heap after a compaction. 298 void print_hrm_post_compaction(); 299 300 // Create a memory mapper for auxiliary data structures of the given size and 301 // translation factor. 302 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 303 size_t size, 304 size_t translation_factor); 305 306 static G1Policy* create_g1_policy(STWGCTimer* gc_timer); 307 308 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 309 310 // These are macros so that, if the assert fires, we get the correct 311 // line number, file, etc. 312 313 #define heap_locking_asserts_params(_extra_message_) \ 314 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 315 (_extra_message_), \ 316 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 317 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 318 BOOL_TO_STR(Thread::current()->is_VM_thread()) 319 320 #define assert_heap_locked() \ 321 do { \ 322 assert(Heap_lock->owned_by_self(), \ 323 heap_locking_asserts_params("should be holding the Heap_lock")); \ 324 } while (0) 325 326 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 327 do { \ 328 assert(Heap_lock->owned_by_self() || \ 329 (SafepointSynchronize::is_at_safepoint() && \ 330 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 331 heap_locking_asserts_params("should be holding the Heap_lock or " \ 332 "should be at a safepoint")); \ 333 } while (0) 334 335 #define assert_heap_locked_and_not_at_safepoint() \ 336 do { \ 337 assert(Heap_lock->owned_by_self() && \ 338 !SafepointSynchronize::is_at_safepoint(), \ 339 heap_locking_asserts_params("should be holding the Heap_lock and " \ 340 "should not be at a safepoint")); \ 341 } while (0) 342 343 #define assert_heap_not_locked() \ 344 do { \ 345 assert(!Heap_lock->owned_by_self(), \ 346 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 347 } while (0) 348 349 #define assert_heap_not_locked_and_not_at_safepoint() \ 350 do { \ 351 assert(!Heap_lock->owned_by_self() && \ 352 !SafepointSynchronize::is_at_safepoint(), \ 353 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 354 "should not be at a safepoint")); \ 355 } while (0) 356 357 #define assert_at_safepoint(_should_be_vm_thread_) \ 358 do { \ 359 assert(SafepointSynchronize::is_at_safepoint() && \ 360 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 361 heap_locking_asserts_params("should be at a safepoint")); \ 362 } while (0) 363 364 #define assert_not_at_safepoint() \ 365 do { \ 366 assert(!SafepointSynchronize::is_at_safepoint(), \ 367 heap_locking_asserts_params("should not be at a safepoint")); \ 368 } while (0) 369 370 protected: 371 372 // The young region list. 373 G1EdenRegions _eden; 374 G1SurvivorRegions _survivor; 375 376 STWGCTimer* _gc_timer_stw; 377 378 G1NewTracer* _gc_tracer_stw; 379 380 // The current policy object for the collector. 381 G1Policy* _g1_policy; 382 G1HeapSizingPolicy* _heap_sizing_policy; 383 384 G1CollectionSet _collection_set; 385 386 // This is the second level of trying to allocate a new region. If 387 // new_region() didn't find a region on the free_list, this call will 388 // check whether there's anything available on the 389 // secondary_free_list and/or wait for more regions to appear on 390 // that list, if _free_regions_coming is set. 391 HeapRegion* new_region_try_secondary_free_list(bool is_old); 392 393 // Try to allocate a single non-humongous HeapRegion sufficient for 394 // an allocation of the given word_size. If do_expand is true, 395 // attempt to expand the heap if necessary to satisfy the allocation 396 // request. If the region is to be used as an old region or for a 397 // humongous object, set is_old to true. If not, to false. 398 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 399 400 // Initialize a contiguous set of free regions of length num_regions 401 // and starting at index first so that they appear as a single 402 // humongous region. 403 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 404 uint num_regions, 405 size_t word_size, 406 AllocationContext_t context); 407 408 // Attempt to allocate a humongous object of the given size. Return 409 // NULL if unsuccessful. 410 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 411 412 // The following two methods, allocate_new_tlab() and 413 // mem_allocate(), are the two main entry points from the runtime 414 // into the G1's allocation routines. They have the following 415 // assumptions: 416 // 417 // * They should both be called outside safepoints. 418 // 419 // * They should both be called without holding the Heap_lock. 420 // 421 // * All allocation requests for new TLABs should go to 422 // allocate_new_tlab(). 423 // 424 // * All non-TLAB allocation requests should go to mem_allocate(). 425 // 426 // * If either call cannot satisfy the allocation request using the 427 // current allocating region, they will try to get a new one. If 428 // this fails, they will attempt to do an evacuation pause and 429 // retry the allocation. 430 // 431 // * If all allocation attempts fail, even after trying to schedule 432 // an evacuation pause, allocate_new_tlab() will return NULL, 433 // whereas mem_allocate() will attempt a heap expansion and/or 434 // schedule a Full GC. 435 // 436 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 437 // should never be called with word_size being humongous. All 438 // humongous allocation requests should go to mem_allocate() which 439 // will satisfy them with a special path. 440 441 virtual HeapWord* allocate_new_tlab(size_t word_size); 442 443 virtual HeapWord* mem_allocate(size_t word_size, 444 bool* gc_overhead_limit_was_exceeded); 445 446 // The following three methods take a gc_count_before_ret 447 // parameter which is used to return the GC count if the method 448 // returns NULL. Given that we are required to read the GC count 449 // while holding the Heap_lock, and these paths will take the 450 // Heap_lock at some point, it's easier to get them to read the GC 451 // count while holding the Heap_lock before they return NULL instead 452 // of the caller (namely: mem_allocate()) having to also take the 453 // Heap_lock just to read the GC count. 454 455 // First-level mutator allocation attempt: try to allocate out of 456 // the mutator alloc region without taking the Heap_lock. This 457 // should only be used for non-humongous allocations. 458 inline HeapWord* attempt_allocation(size_t word_size, 459 uint* gc_count_before_ret, 460 uint* gclocker_retry_count_ret); 461 462 // Second-level mutator allocation attempt: take the Heap_lock and 463 // retry the allocation attempt, potentially scheduling a GC 464 // pause. This should only be used for non-humongous allocations. 465 HeapWord* attempt_allocation_slow(size_t word_size, 466 AllocationContext_t context, 467 uint* gc_count_before_ret, 468 uint* gclocker_retry_count_ret); 469 470 // Takes the Heap_lock and attempts a humongous allocation. It can 471 // potentially schedule a GC pause. 472 HeapWord* attempt_allocation_humongous(size_t word_size, 473 uint* gc_count_before_ret, 474 uint* gclocker_retry_count_ret); 475 476 // Allocation attempt that should be called during safepoints (e.g., 477 // at the end of a successful GC). expect_null_mutator_alloc_region 478 // specifies whether the mutator alloc region is expected to be NULL 479 // or not. 480 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 481 AllocationContext_t context, 482 bool expect_null_mutator_alloc_region); 483 484 // These methods are the "callbacks" from the G1AllocRegion class. 485 486 // For mutator alloc regions. 487 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 488 void retire_mutator_alloc_region(HeapRegion* alloc_region, 489 size_t allocated_bytes); 490 491 // For GC alloc regions. 492 bool has_more_regions(InCSetState dest); 493 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest); 494 void retire_gc_alloc_region(HeapRegion* alloc_region, 495 size_t allocated_bytes, InCSetState dest); 496 497 // - if explicit_gc is true, the GC is for a System.gc() etc, 498 // otherwise it's for a failed allocation. 499 // - if clear_all_soft_refs is true, all soft references should be 500 // cleared during the GC. 501 // - it returns false if it is unable to do the collection due to the 502 // GC locker being active, true otherwise. 503 bool do_full_collection(bool explicit_gc, 504 bool clear_all_soft_refs); 505 506 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 507 virtual void do_full_collection(bool clear_all_soft_refs); 508 509 // Resize the heap if necessary after a full collection. 510 void resize_if_necessary_after_full_collection(); 511 512 // Callback from VM_G1CollectForAllocation operation. 513 // This function does everything necessary/possible to satisfy a 514 // failed allocation request (including collection, expansion, etc.) 515 HeapWord* satisfy_failed_allocation(size_t word_size, 516 AllocationContext_t context, 517 bool* succeeded); 518 private: 519 // Internal helpers used during full GC to split it up to 520 // increase readability. 521 void abort_concurrent_cycle(); 522 void verify_before_full_collection(bool explicit_gc); 523 void prepare_heap_for_full_collection(); 524 void prepare_heap_for_mutators(); 525 void abort_refinement(); 526 void verify_after_full_collection(); 527 void print_heap_after_full_collection(G1HeapTransition* heap_transition); 528 529 // Verification type helper. 530 G1HeapVerifier::G1VerifyType young_verification_type(); 531 532 // Helper method for satisfy_failed_allocation() 533 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 534 AllocationContext_t context, 535 bool do_gc, 536 bool clear_all_soft_refs, 537 bool expect_null_mutator_alloc_region, 538 bool* gc_succeeded); 539 540 protected: 541 // Attempting to expand the heap sufficiently 542 // to support an allocation of the given "word_size". If 543 // successful, perform the allocation and return the address of the 544 // allocated block, or else "NULL". 545 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 546 547 // Preserve any referents discovered by concurrent marking that have not yet been 548 // copied by the STW pause. 549 void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states); 550 // Process any reference objects discovered during 551 // an incremental evacuation pause. 552 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 553 554 // Enqueue any remaining discovered references 555 // after processing. 556 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states); 557 558 // Merges the information gathered on a per-thread basis for all worker threads 559 // during GC into global variables. 560 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states); 561 public: 562 G1YoungRemSetSamplingThread* sampling_thread() const { return _young_gen_sampling_thread; } 563 564 WorkGang* workers() const { return _workers; } 565 566 G1Allocator* allocator() { 567 return _allocator; 568 } 569 570 G1HeapVerifier* verifier() { 571 return _verifier; 572 } 573 574 G1MonitoringSupport* g1mm() { 575 assert(_g1mm != NULL, "should have been initialized"); 576 return _g1mm; 577 } 578 579 // Expand the garbage-first heap by at least the given size (in bytes!). 580 // Returns true if the heap was expanded by the requested amount; 581 // false otherwise. 582 // (Rounds up to a HeapRegion boundary.) 583 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL); 584 585 // Returns the PLAB statistics for a given destination. 586 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 587 588 // Determines PLAB size for a given destination. 589 inline size_t desired_plab_sz(InCSetState dest); 590 591 inline AllocationContextStats& allocation_context_stats(); 592 593 // Do anything common to GC's. 594 void gc_prologue(bool full); 595 void gc_epilogue(bool full); 596 597 // Modify the reclaim candidate set and test for presence. 598 // These are only valid for starts_humongous regions. 599 inline void set_humongous_reclaim_candidate(uint region, bool value); 600 inline bool is_humongous_reclaim_candidate(uint region); 601 602 // Remove from the reclaim candidate set. Also remove from the 603 // collection set so that later encounters avoid the slow path. 604 inline void set_humongous_is_live(oop obj); 605 606 // Register the given region to be part of the collection set. 607 inline void register_humongous_region_with_cset(uint index); 608 // Register regions with humongous objects (actually on the start region) in 609 // the in_cset_fast_test table. 610 void register_humongous_regions_with_cset(); 611 // We register a region with the fast "in collection set" test. We 612 // simply set to true the array slot corresponding to this region. 613 void register_young_region_with_cset(HeapRegion* r) { 614 _in_cset_fast_test.set_in_young(r->hrm_index()); 615 } 616 void register_old_region_with_cset(HeapRegion* r) { 617 _in_cset_fast_test.set_in_old(r->hrm_index()); 618 } 619 inline void register_ext_region_with_cset(HeapRegion* r) { 620 _in_cset_fast_test.set_ext(r->hrm_index()); 621 } 622 void clear_in_cset(const HeapRegion* hr) { 623 _in_cset_fast_test.clear(hr); 624 } 625 626 void clear_cset_fast_test() { 627 _in_cset_fast_test.clear(); 628 } 629 630 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 631 632 // This is called at the start of either a concurrent cycle or a Full 633 // GC to update the number of old marking cycles started. 634 void increment_old_marking_cycles_started(); 635 636 // This is called at the end of either a concurrent cycle or a Full 637 // GC to update the number of old marking cycles completed. Those two 638 // can happen in a nested fashion, i.e., we start a concurrent 639 // cycle, a Full GC happens half-way through it which ends first, 640 // and then the cycle notices that a Full GC happened and ends 641 // too. The concurrent parameter is a boolean to help us do a bit 642 // tighter consistency checking in the method. If concurrent is 643 // false, the caller is the inner caller in the nesting (i.e., the 644 // Full GC). If concurrent is true, the caller is the outer caller 645 // in this nesting (i.e., the concurrent cycle). Further nesting is 646 // not currently supported. The end of this call also notifies 647 // the FullGCCount_lock in case a Java thread is waiting for a full 648 // GC to happen (e.g., it called System.gc() with 649 // +ExplicitGCInvokesConcurrent). 650 void increment_old_marking_cycles_completed(bool concurrent); 651 652 uint old_marking_cycles_completed() { 653 return _old_marking_cycles_completed; 654 } 655 656 G1HRPrinter* hr_printer() { return &_hr_printer; } 657 658 // Allocates a new heap region instance. 659 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 660 661 // Allocate the highest free region in the reserved heap. This will commit 662 // regions as necessary. 663 HeapRegion* alloc_highest_free_region(); 664 665 // Frees a non-humongous region by initializing its contents and 666 // adding it to the free list that's passed as a parameter (this is 667 // usually a local list which will be appended to the master free 668 // list later). The used bytes of freed regions are accumulated in 669 // pre_used. If skip_remset is true, the region's RSet will not be freed 670 // up. If skip_hot_card_cache is true, the region's hot card cache will not 671 // be freed up. The assumption is that this will be done later. 672 // The locked parameter indicates if the caller has already taken 673 // care of proper synchronization. This may allow some optimizations. 674 void free_region(HeapRegion* hr, 675 FreeRegionList* free_list, 676 bool skip_remset, 677 bool skip_hot_card_cache = false, 678 bool locked = false); 679 680 // It dirties the cards that cover the block so that the post 681 // write barrier never queues anything when updating objects on this 682 // block. It is assumed (and in fact we assert) that the block 683 // belongs to a young region. 684 inline void dirty_young_block(HeapWord* start, size_t word_size); 685 686 // Frees a humongous region by collapsing it into individual regions 687 // and calling free_region() for each of them. The freed regions 688 // will be added to the free list that's passed as a parameter (this 689 // is usually a local list which will be appended to the master free 690 // list later). The used bytes of freed regions are accumulated in 691 // pre_used. If skip_remset is true, the region's RSet will not be freed 692 // up. The assumption is that this will be done later. 693 void free_humongous_region(HeapRegion* hr, 694 FreeRegionList* free_list, 695 bool skip_remset); 696 697 // Facility for allocating in 'archive' regions in high heap memory and 698 // recording the allocated ranges. These should all be called from the 699 // VM thread at safepoints, without the heap lock held. They can be used 700 // to create and archive a set of heap regions which can be mapped at the 701 // same fixed addresses in a subsequent JVM invocation. 702 void begin_archive_alloc_range(bool open = false); 703 704 // Check if the requested size would be too large for an archive allocation. 705 bool is_archive_alloc_too_large(size_t word_size); 706 707 // Allocate memory of the requested size from the archive region. This will 708 // return NULL if the size is too large or if no memory is available. It 709 // does not trigger a garbage collection. 710 HeapWord* archive_mem_allocate(size_t word_size); 711 712 // Optionally aligns the end address and returns the allocated ranges in 713 // an array of MemRegions in order of ascending addresses. 714 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 715 size_t end_alignment_in_bytes = 0); 716 717 // Facility for allocating a fixed range within the heap and marking 718 // the containing regions as 'archive'. For use at JVM init time, when the 719 // caller may mmap archived heap data at the specified range(s). 720 // Verify that the MemRegions specified in the argument array are within the 721 // reserved heap. 722 bool check_archive_addresses(MemRegion* range, size_t count); 723 724 // Commit the appropriate G1 regions containing the specified MemRegions 725 // and mark them as 'archive' regions. The regions in the array must be 726 // non-overlapping and in order of ascending address. 727 bool alloc_archive_regions(MemRegion* range, size_t count, bool open); 728 729 // Insert any required filler objects in the G1 regions around the specified 730 // ranges to make the regions parseable. This must be called after 731 // alloc_archive_regions, and after class loading has occurred. 732 void fill_archive_regions(MemRegion* range, size_t count); 733 734 // For each of the specified MemRegions, uncommit the containing G1 regions 735 // which had been allocated by alloc_archive_regions. This should be called 736 // rather than fill_archive_regions at JVM init time if the archive file 737 // mapping failed, with the same non-overlapping and sorted MemRegion array. 738 void dealloc_archive_regions(MemRegion* range, size_t count); 739 740 protected: 741 742 // Shrink the garbage-first heap by at most the given size (in bytes!). 743 // (Rounds down to a HeapRegion boundary.) 744 virtual void shrink(size_t expand_bytes); 745 void shrink_helper(size_t expand_bytes); 746 747 #if TASKQUEUE_STATS 748 static void print_taskqueue_stats_hdr(outputStream* const st); 749 void print_taskqueue_stats() const; 750 void reset_taskqueue_stats(); 751 #endif // TASKQUEUE_STATS 752 753 // Schedule the VM operation that will do an evacuation pause to 754 // satisfy an allocation request of word_size. *succeeded will 755 // return whether the VM operation was successful (it did do an 756 // evacuation pause) or not (another thread beat us to it or the GC 757 // locker was active). Given that we should not be holding the 758 // Heap_lock when we enter this method, we will pass the 759 // gc_count_before (i.e., total_collections()) as a parameter since 760 // it has to be read while holding the Heap_lock. Currently, both 761 // methods that call do_collection_pause() release the Heap_lock 762 // before the call, so it's easy to read gc_count_before just before. 763 HeapWord* do_collection_pause(size_t word_size, 764 uint gc_count_before, 765 bool* succeeded, 766 GCCause::Cause gc_cause); 767 768 void wait_for_root_region_scanning(); 769 770 // The guts of the incremental collection pause, executed by the vm 771 // thread. It returns false if it is unable to do the collection due 772 // to the GC locker being active, true otherwise 773 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 774 775 // Actually do the work of evacuating the collection set. 776 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states); 777 778 void pre_evacuate_collection_set(); 779 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 780 781 // Print the header for the per-thread termination statistics. 782 static void print_termination_stats_hdr(); 783 // Print actual per-thread termination statistics. 784 void print_termination_stats(uint worker_id, 785 double elapsed_ms, 786 double strong_roots_ms, 787 double term_ms, 788 size_t term_attempts, 789 size_t alloc_buffer_waste, 790 size_t undo_waste) const; 791 // Update object copying statistics. 792 void record_obj_copy_mem_stats(); 793 794 // The hot card cache for remembered set insertion optimization. 795 G1HotCardCache* _hot_card_cache; 796 797 // The g1 remembered set of the heap. 798 G1RemSet* _g1_rem_set; 799 800 // A set of cards that cover the objects for which the Rsets should be updated 801 // concurrently after the collection. 802 DirtyCardQueueSet _dirty_card_queue_set; 803 804 // After a collection pause, convert the regions in the collection set into free 805 // regions. 806 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 807 808 // Abandon the current collection set without recording policy 809 // statistics or updating free lists. 810 void abandon_collection_set(G1CollectionSet* collection_set); 811 812 // The concurrent marker (and the thread it runs in.) 813 G1ConcurrentMark* _cm; 814 ConcurrentMarkThread* _cmThread; 815 816 // The concurrent refiner. 817 G1ConcurrentRefine* _cr; 818 819 // The parallel task queues 820 RefToScanQueueSet *_task_queues; 821 822 // True iff a evacuation has failed in the current collection. 823 bool _evacuation_failed; 824 825 EvacuationFailedInfo* _evacuation_failed_info_array; 826 827 // Failed evacuations cause some logical from-space objects to have 828 // forwarding pointers to themselves. Reset them. 829 void remove_self_forwarding_pointers(); 830 831 // Restore the objects in the regions in the collection set after an 832 // evacuation failure. 833 void restore_after_evac_failure(); 834 835 PreservedMarksSet _preserved_marks_set; 836 837 // Preserve the mark of "obj", if necessary, in preparation for its mark 838 // word being overwritten with a self-forwarding-pointer. 839 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 840 841 #ifndef PRODUCT 842 // Support for forcing evacuation failures. Analogous to 843 // PromotionFailureALot for the other collectors. 844 845 // Records whether G1EvacuationFailureALot should be in effect 846 // for the current GC 847 bool _evacuation_failure_alot_for_current_gc; 848 849 // Used to record the GC number for interval checking when 850 // determining whether G1EvaucationFailureALot is in effect 851 // for the current GC. 852 size_t _evacuation_failure_alot_gc_number; 853 854 // Count of the number of evacuations between failures. 855 volatile size_t _evacuation_failure_alot_count; 856 857 // Set whether G1EvacuationFailureALot should be in effect 858 // for the current GC (based upon the type of GC and which 859 // command line flags are set); 860 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 861 bool during_initial_mark, 862 bool during_marking); 863 864 inline void set_evacuation_failure_alot_for_current_gc(); 865 866 // Return true if it's time to cause an evacuation failure. 867 inline bool evacuation_should_fail(); 868 869 // Reset the G1EvacuationFailureALot counters. Should be called at 870 // the end of an evacuation pause in which an evacuation failure occurred. 871 inline void reset_evacuation_should_fail(); 872 #endif // !PRODUCT 873 874 // ("Weak") Reference processing support. 875 // 876 // G1 has 2 instances of the reference processor class. One 877 // (_ref_processor_cm) handles reference object discovery 878 // and subsequent processing during concurrent marking cycles. 879 // 880 // The other (_ref_processor_stw) handles reference object 881 // discovery and processing during full GCs and incremental 882 // evacuation pauses. 883 // 884 // During an incremental pause, reference discovery will be 885 // temporarily disabled for _ref_processor_cm and will be 886 // enabled for _ref_processor_stw. At the end of the evacuation 887 // pause references discovered by _ref_processor_stw will be 888 // processed and discovery will be disabled. The previous 889 // setting for reference object discovery for _ref_processor_cm 890 // will be re-instated. 891 // 892 // At the start of marking: 893 // * Discovery by the CM ref processor is verified to be inactive 894 // and it's discovered lists are empty. 895 // * Discovery by the CM ref processor is then enabled. 896 // 897 // At the end of marking: 898 // * Any references on the CM ref processor's discovered 899 // lists are processed (possibly MT). 900 // 901 // At the start of full GC we: 902 // * Disable discovery by the CM ref processor and 903 // empty CM ref processor's discovered lists 904 // (without processing any entries). 905 // * Verify that the STW ref processor is inactive and it's 906 // discovered lists are empty. 907 // * Temporarily set STW ref processor discovery as single threaded. 908 // * Temporarily clear the STW ref processor's _is_alive_non_header 909 // field. 910 // * Finally enable discovery by the STW ref processor. 911 // 912 // The STW ref processor is used to record any discovered 913 // references during the full GC. 914 // 915 // At the end of a full GC we: 916 // * Enqueue any reference objects discovered by the STW ref processor 917 // that have non-live referents. This has the side-effect of 918 // making the STW ref processor inactive by disabling discovery. 919 // * Verify that the CM ref processor is still inactive 920 // and no references have been placed on it's discovered 921 // lists (also checked as a precondition during initial marking). 922 923 // The (stw) reference processor... 924 ReferenceProcessor* _ref_processor_stw; 925 926 // During reference object discovery, the _is_alive_non_header 927 // closure (if non-null) is applied to the referent object to 928 // determine whether the referent is live. If so then the 929 // reference object does not need to be 'discovered' and can 930 // be treated as a regular oop. This has the benefit of reducing 931 // the number of 'discovered' reference objects that need to 932 // be processed. 933 // 934 // Instance of the is_alive closure for embedding into the 935 // STW reference processor as the _is_alive_non_header field. 936 // Supplying a value for the _is_alive_non_header field is 937 // optional but doing so prevents unnecessary additions to 938 // the discovered lists during reference discovery. 939 G1STWIsAliveClosure _is_alive_closure_stw; 940 941 // The (concurrent marking) reference processor... 942 ReferenceProcessor* _ref_processor_cm; 943 944 // Instance of the concurrent mark is_alive closure for embedding 945 // into the Concurrent Marking reference processor as the 946 // _is_alive_non_header field. Supplying a value for the 947 // _is_alive_non_header field is optional but doing so prevents 948 // unnecessary additions to the discovered lists during reference 949 // discovery. 950 G1CMIsAliveClosure _is_alive_closure_cm; 951 952 volatile bool _free_regions_coming; 953 954 public: 955 956 RefToScanQueue *task_queue(uint i) const; 957 958 uint num_task_queues() const; 959 960 // A set of cards where updates happened during the GC 961 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 962 963 // Create a G1CollectedHeap with the specified policy. 964 // Must call the initialize method afterwards. 965 // May not return if something goes wrong. 966 G1CollectedHeap(G1CollectorPolicy* policy); 967 968 private: 969 jint initialize_concurrent_refinement(); 970 jint initialize_young_gen_sampling_thread(); 971 public: 972 // Initialize the G1CollectedHeap to have the initial and 973 // maximum sizes and remembered and barrier sets 974 // specified by the policy object. 975 jint initialize(); 976 977 virtual void stop(); 978 virtual void safepoint_synchronize_begin(); 979 virtual void safepoint_synchronize_end(); 980 981 // Return the (conservative) maximum heap alignment for any G1 heap 982 static size_t conservative_max_heap_alignment(); 983 984 // Does operations required after initialization has been done. 985 void post_initialize(); 986 987 // Initialize weak reference processing. 988 void ref_processing_init(); 989 990 virtual Name kind() const { 991 return CollectedHeap::G1CollectedHeap; 992 } 993 994 virtual const char* name() const { 995 return "G1"; 996 } 997 998 const G1CollectorState* collector_state() const { return &_collector_state; } 999 G1CollectorState* collector_state() { return &_collector_state; } 1000 1001 // The current policy object for the collector. 1002 G1Policy* g1_policy() const { return _g1_policy; } 1003 1004 const G1CollectionSet* collection_set() const { return &_collection_set; } 1005 G1CollectionSet* collection_set() { return &_collection_set; } 1006 1007 virtual CollectorPolicy* collector_policy() const; 1008 1009 // Adaptive size policy. No such thing for g1. 1010 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1011 1012 // The rem set and barrier set. 1013 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1014 1015 // Try to minimize the remembered set. 1016 void scrub_rem_set(); 1017 1018 uint get_gc_time_stamp() { 1019 return _gc_time_stamp; 1020 } 1021 1022 inline void reset_gc_time_stamp(); 1023 1024 void check_gc_time_stamps() PRODUCT_RETURN; 1025 1026 inline void increment_gc_time_stamp(); 1027 1028 // Reset the given region's GC timestamp. If it's starts humongous, 1029 // also reset the GC timestamp of its corresponding 1030 // continues humongous regions too. 1031 void reset_gc_time_stamps(HeapRegion* hr); 1032 1033 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 1034 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i); 1035 1036 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. 1037 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i); 1038 1039 // The shared block offset table array. 1040 G1BlockOffsetTable* bot() const { return _bot; } 1041 1042 // Reference Processing accessors 1043 1044 // The STW reference processor.... 1045 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1046 1047 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1048 1049 // The Concurrent Marking reference processor... 1050 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1051 1052 size_t unused_committed_regions_in_bytes() const; 1053 virtual size_t capacity() const; 1054 virtual size_t used() const; 1055 // This should be called when we're not holding the heap lock. The 1056 // result might be a bit inaccurate. 1057 size_t used_unlocked() const; 1058 size_t recalculate_used() const; 1059 1060 // These virtual functions do the actual allocation. 1061 // Some heaps may offer a contiguous region for shared non-blocking 1062 // allocation, via inlined code (by exporting the address of the top and 1063 // end fields defining the extent of the contiguous allocation region.) 1064 // But G1CollectedHeap doesn't yet support this. 1065 1066 virtual bool is_maximal_no_gc() const { 1067 return _hrm.available() == 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