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/g1HeapVerifier.hpp" 38 #include "gc/g1/g1HRPrinter.hpp" 39 #include "gc/g1/g1InCSetState.hpp" 40 #include "gc/g1/g1MonitoringSupport.hpp" 41 #include "gc/g1/g1SATBCardTableModRefBS.hpp" 42 #include "gc/g1/g1SurvivorRegions.hpp" 43 #include "gc/g1/g1YCTypes.hpp" 44 #include "gc/g1/hSpaceCounters.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/plab.hpp" 50 #include "gc/shared/preservedMarks.hpp" 51 #include "memory/memRegion.hpp" 52 #include "utilities/stack.hpp" 53 54 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 55 // It uses the "Garbage First" heap organization and algorithm, which 56 // may combine concurrent marking with parallel, incremental compaction of 57 // heap subsets that will yield large amounts of garbage. 58 59 // Forward declarations 60 class HeapRegion; 61 class HRRSCleanupTask; 62 class GenerationSpec; 63 class OopsInHeapRegionClosure; 64 class G1ParScanThreadState; 65 class G1ParScanThreadStateSet; 66 class G1KlassScanClosure; 67 class G1ParScanThreadState; 68 class ObjectClosure; 69 class SpaceClosure; 70 class CompactibleSpaceClosure; 71 class Space; 72 class G1CollectionSet; 73 class G1CollectorPolicy; 74 class G1Policy; 75 class G1HotCardCache; 76 class G1RemSet; 77 class HeapRegionRemSetIterator; 78 class G1ConcurrentMark; 79 class ConcurrentMarkThread; 80 class ConcurrentG1Refine; 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 94 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 95 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 96 97 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 98 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 99 100 // The G1 STW is alive closure. 101 // An instance is embedded into the G1CH and used as the 102 // (optional) _is_alive_non_header closure in the STW 103 // reference processor. It is also extensively used during 104 // reference processing during STW evacuation pauses. 105 class G1STWIsAliveClosure: public BoolObjectClosure { 106 G1CollectedHeap* _g1; 107 public: 108 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 109 bool do_object_b(oop p); 110 }; 111 112 class RefineCardTableEntryClosure; 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 G1GCAllocRegion; 130 friend class G1HeapVerifier; 131 132 // Closures used in implementation. 133 friend class G1ParScanThreadState; 134 friend class G1ParScanThreadStateSet; 135 friend class G1ParTask; 136 friend class G1PLABAllocator; 137 friend class G1PrepareCompactClosure; 138 139 // Other related classes. 140 friend class HeapRegionClaimer; 141 142 // Testing classes. 143 friend class G1CheckCSetFastTableClosure; 144 145 private: 146 WorkGang* _workers; 147 G1CollectorPolicy* _collector_policy; 148 149 static size_t _humongous_object_threshold_in_words; 150 151 // The secondary free list which contains regions that have been 152 // freed up during the cleanup process. This will be appended to 153 // the master free list when appropriate. 154 FreeRegionList _secondary_free_list; 155 156 // It keeps track of the old regions. 157 HeapRegionSet _old_set; 158 159 // It keeps track of the humongous regions. 160 HeapRegionSet _humongous_set; 161 162 void eagerly_reclaim_humongous_regions(); 163 // Start a new incremental collection set for the next pause. 164 void start_new_collection_set(); 165 166 // The number of regions we could create by expansion. 167 uint _expansion_regions; 168 169 // The block offset table for the G1 heap. 170 G1BlockOffsetTable* _bot; 171 172 // Tears down the region sets / lists so that they are empty and the 173 // regions on the heap do not belong to a region set / list. The 174 // only exception is the humongous set which we leave unaltered. If 175 // free_list_only is true, it will only tear down the master free 176 // list. It is called before a Full GC (free_list_only == false) or 177 // before heap shrinking (free_list_only == true). 178 void tear_down_region_sets(bool free_list_only); 179 180 // Rebuilds the region sets / lists so that they are repopulated to 181 // reflect the contents of the heap. The only exception is the 182 // humongous set which was not torn down in the first place. If 183 // free_list_only is true, it will only rebuild the master free 184 // list. It is called after a Full GC (free_list_only == false) or 185 // after heap shrinking (free_list_only == true). 186 void rebuild_region_sets(bool free_list_only); 187 188 // Callback for region mapping changed events. 189 G1RegionMappingChangedListener _listener; 190 191 // The sequence of all heap regions in the heap. 192 HeapRegionManager _hrm; 193 194 // Manages all allocations with regions except humongous object allocations. 195 G1Allocator* _allocator; 196 197 // Manages all heap verification. 198 G1HeapVerifier* _verifier; 199 200 // Outside of GC pauses, the number of bytes used in all regions other 201 // than the current allocation region(s). 202 size_t _summary_bytes_used; 203 204 void increase_used(size_t bytes); 205 void decrease_used(size_t bytes); 206 207 void set_used(size_t bytes); 208 209 // Class that handles archive allocation ranges. 210 G1ArchiveAllocator* _archive_allocator; 211 212 // Statistics for each allocation context 213 AllocationContextStats _allocation_context_stats; 214 215 // GC allocation statistics policy for survivors. 216 G1EvacStats _survivor_evac_stats; 217 218 // GC allocation statistics policy for tenured objects. 219 G1EvacStats _old_evac_stats; 220 221 // It specifies whether we should attempt to expand the heap after a 222 // region allocation failure. If heap expansion fails we set this to 223 // false so that we don't re-attempt the heap expansion (it's likely 224 // that subsequent expansion attempts will also fail if one fails). 225 // Currently, it is only consulted during GC and it's reset at the 226 // start of each GC. 227 bool _expand_heap_after_alloc_failure; 228 229 // Helper for monitoring and management support. 230 G1MonitoringSupport* _g1mm; 231 232 // Records whether the region at the given index is (still) a 233 // candidate for eager reclaim. Only valid for humongous start 234 // regions; other regions have unspecified values. Humongous start 235 // regions are initialized at start of collection pause, with 236 // candidates removed from the set as they are found reachable from 237 // roots or the young generation. 238 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 239 protected: 240 bool default_value() const { return false; } 241 public: 242 void clear() { G1BiasedMappedArray<bool>::clear(); } 243 void set_candidate(uint region, bool value) { 244 set_by_index(region, value); 245 } 246 bool is_candidate(uint region) { 247 return get_by_index(region); 248 } 249 }; 250 251 HumongousReclaimCandidates _humongous_reclaim_candidates; 252 // Stores whether during humongous object registration we found candidate regions. 253 // If not, we can skip a few steps. 254 bool _has_humongous_reclaim_candidates; 255 256 volatile uint _gc_time_stamp; 257 258 G1HRPrinter _hr_printer; 259 260 // It decides whether an explicit GC should start a concurrent cycle 261 // instead of doing a STW GC. Currently, a concurrent cycle is 262 // explicitly started if: 263 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 264 // (b) cause == _g1_humongous_allocation 265 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 266 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 267 // (e) cause == _update_allocation_context_stats_inc 268 // (f) cause == _wb_conc_mark 269 bool should_do_concurrent_full_gc(GCCause::Cause cause); 270 271 // indicates whether we are in young or mixed GC mode 272 G1CollectorState _collector_state; 273 274 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 275 // concurrent cycles) we have started. 276 volatile uint _old_marking_cycles_started; 277 278 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 279 // concurrent cycles) we have completed. 280 volatile uint _old_marking_cycles_completed; 281 282 // This is a non-product method that is helpful for testing. It is 283 // called at the end of a GC and artificially expands the heap by 284 // allocating a number of dead regions. This way we can induce very 285 // frequent marking cycles and stress the cleanup / concurrent 286 // cleanup code more (as all the regions that will be allocated by 287 // this method will be found dead by the marking cycle). 288 void allocate_dummy_regions() PRODUCT_RETURN; 289 290 // Clear RSets after a compaction. It also resets the GC time stamps. 291 void clear_rsets_post_compaction(); 292 293 // If the HR printer is active, dump the state of the regions in the 294 // heap after a compaction. 295 void print_hrm_post_compaction(); 296 297 // Create a memory mapper for auxiliary data structures of the given size and 298 // translation factor. 299 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 300 size_t size, 301 size_t translation_factor); 302 303 static G1Policy* create_g1_policy(); 304 305 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 306 307 void process_weak_jni_handles(); 308 309 // These are macros so that, if the assert fires, we get the correct 310 // line number, file, etc. 311 312 #define heap_locking_asserts_params(_extra_message_) \ 313 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 314 (_extra_message_), \ 315 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 316 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 317 BOOL_TO_STR(Thread::current()->is_VM_thread()) 318 319 #define assert_heap_locked() \ 320 do { \ 321 assert(Heap_lock->owned_by_self(), \ 322 heap_locking_asserts_params("should be holding the Heap_lock")); \ 323 } while (0) 324 325 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 326 do { \ 327 assert(Heap_lock->owned_by_self() || \ 328 (SafepointSynchronize::is_at_safepoint() && \ 329 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 330 heap_locking_asserts_params("should be holding the Heap_lock or " \ 331 "should be at a safepoint")); \ 332 } while (0) 333 334 #define assert_heap_locked_and_not_at_safepoint() \ 335 do { \ 336 assert(Heap_lock->owned_by_self() && \ 337 !SafepointSynchronize::is_at_safepoint(), \ 338 heap_locking_asserts_params("should be holding the Heap_lock and " \ 339 "should not be at a safepoint")); \ 340 } while (0) 341 342 #define assert_heap_not_locked() \ 343 do { \ 344 assert(!Heap_lock->owned_by_self(), \ 345 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 346 } while (0) 347 348 #define assert_heap_not_locked_and_not_at_safepoint() \ 349 do { \ 350 assert(!Heap_lock->owned_by_self() && \ 351 !SafepointSynchronize::is_at_safepoint(), \ 352 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 353 "should not be at a safepoint")); \ 354 } while (0) 355 356 #define assert_at_safepoint(_should_be_vm_thread_) \ 357 do { \ 358 assert(SafepointSynchronize::is_at_safepoint() && \ 359 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 360 heap_locking_asserts_params("should be at a safepoint")); \ 361 } while (0) 362 363 #define assert_not_at_safepoint() \ 364 do { \ 365 assert(!SafepointSynchronize::is_at_safepoint(), \ 366 heap_locking_asserts_params("should not be at a safepoint")); \ 367 } while (0) 368 369 protected: 370 371 // The young region list. 372 G1EdenRegions _eden; 373 G1SurvivorRegions _survivor; 374 375 // The current policy object for the collector. 376 G1Policy* _g1_policy; 377 G1HeapSizingPolicy* _heap_sizing_policy; 378 379 G1CollectionSet _collection_set; 380 381 // This is the second level of trying to allocate a new region. If 382 // new_region() didn't find a region on the free_list, this call will 383 // check whether there's anything available on the 384 // secondary_free_list and/or wait for more regions to appear on 385 // that list, if _free_regions_coming is set. 386 HeapRegion* new_region_try_secondary_free_list(bool is_old); 387 388 // Try to allocate a single non-humongous HeapRegion sufficient for 389 // an allocation of the given word_size. If do_expand is true, 390 // attempt to expand the heap if necessary to satisfy the allocation 391 // request. If the region is to be used as an old region or for a 392 // humongous object, set is_old to true. If not, to false. 393 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 394 395 // Initialize a contiguous set of free regions of length num_regions 396 // and starting at index first so that they appear as a single 397 // humongous region. 398 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 399 uint num_regions, 400 size_t word_size, 401 AllocationContext_t context); 402 403 // Attempt to allocate a humongous object of the given size. Return 404 // NULL if unsuccessful. 405 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 406 407 // The following two methods, allocate_new_tlab() and 408 // mem_allocate(), are the two main entry points from the runtime 409 // into the G1's allocation routines. They have the following 410 // assumptions: 411 // 412 // * They should both be called outside safepoints. 413 // 414 // * They should both be called without holding the Heap_lock. 415 // 416 // * All allocation requests for new TLABs should go to 417 // allocate_new_tlab(). 418 // 419 // * All non-TLAB allocation requests should go to mem_allocate(). 420 // 421 // * If either call cannot satisfy the allocation request using the 422 // current allocating region, they will try to get a new one. If 423 // this fails, they will attempt to do an evacuation pause and 424 // retry the allocation. 425 // 426 // * If all allocation attempts fail, even after trying to schedule 427 // an evacuation pause, allocate_new_tlab() will return NULL, 428 // whereas mem_allocate() will attempt a heap expansion and/or 429 // schedule a Full GC. 430 // 431 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 432 // should never be called with word_size being humongous. All 433 // humongous allocation requests should go to mem_allocate() which 434 // will satisfy them with a special path. 435 436 virtual HeapWord* allocate_new_tlab(size_t word_size); 437 438 virtual HeapWord* mem_allocate(size_t word_size, 439 bool* gc_overhead_limit_was_exceeded); 440 441 // The following three methods take a gc_count_before_ret 442 // parameter which is used to return the GC count if the method 443 // returns NULL. Given that we are required to read the GC count 444 // while holding the Heap_lock, and these paths will take the 445 // Heap_lock at some point, it's easier to get them to read the GC 446 // count while holding the Heap_lock before they return NULL instead 447 // of the caller (namely: mem_allocate()) having to also take the 448 // Heap_lock just to read the GC count. 449 450 // First-level mutator allocation attempt: try to allocate out of 451 // the mutator alloc region without taking the Heap_lock. This 452 // should only be used for non-humongous allocations. 453 inline HeapWord* attempt_allocation(size_t word_size, 454 uint* gc_count_before_ret, 455 uint* gclocker_retry_count_ret); 456 457 // Second-level mutator allocation attempt: take the Heap_lock and 458 // retry the allocation attempt, potentially scheduling a GC 459 // pause. This should only be used for non-humongous allocations. 460 HeapWord* attempt_allocation_slow(size_t word_size, 461 AllocationContext_t context, 462 uint* gc_count_before_ret, 463 uint* gclocker_retry_count_ret); 464 465 // Takes the Heap_lock and attempts a humongous allocation. It can 466 // potentially schedule a GC pause. 467 HeapWord* attempt_allocation_humongous(size_t word_size, 468 uint* gc_count_before_ret, 469 uint* gclocker_retry_count_ret); 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 do_full_collection_inner(G1FullGCScope* scope); 517 void abort_concurrent_cycle(); 518 void prepare_heap_for_full_collection(); 519 void reset_card_cache_and_queue(); 520 void verify_before_full_collection(bool explicit_gc); 521 void verify_after_full_collection(); 522 523 // Helper method for satisfy_failed_allocation() 524 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 525 AllocationContext_t context, 526 bool do_gc, 527 bool clear_all_soft_refs, 528 bool expect_null_mutator_alloc_region, 529 bool* gc_succeeded); 530 531 protected: 532 // Attempting to expand the heap sufficiently 533 // to support an allocation of the given "word_size". If 534 // successful, perform the allocation and return the address of the 535 // allocated block, or else "NULL". 536 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 537 538 // Preserve any referents discovered by concurrent marking that have not yet been 539 // copied by the STW pause. 540 void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states); 541 // Process any reference objects discovered during 542 // an incremental evacuation pause. 543 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 544 545 // Enqueue any remaining discovered references 546 // after processing. 547 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states); 548 549 // Merges the information gathered on a per-thread basis for all worker threads 550 // during GC into global variables. 551 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states); 552 public: 553 WorkGang* workers() const { return _workers; } 554 555 G1Allocator* allocator() { 556 return _allocator; 557 } 558 559 G1HeapVerifier* verifier() { 560 return _verifier; 561 } 562 563 G1MonitoringSupport* g1mm() { 564 assert(_g1mm != NULL, "should have been initialized"); 565 return _g1mm; 566 } 567 568 // Expand the garbage-first heap by at least the given size (in bytes!). 569 // Returns true if the heap was expanded by the requested amount; 570 // false otherwise. 571 // (Rounds up to a HeapRegion boundary.) 572 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL); 573 574 // Returns the PLAB statistics for a given destination. 575 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 576 577 // Determines PLAB size for a given destination. 578 inline size_t desired_plab_sz(InCSetState dest); 579 580 inline AllocationContextStats& allocation_context_stats(); 581 582 // Do anything common to GC's. 583 void gc_prologue(bool full); 584 void gc_epilogue(bool full); 585 586 // Modify the reclaim candidate set and test for presence. 587 // These are only valid for starts_humongous regions. 588 inline void set_humongous_reclaim_candidate(uint region, bool value); 589 inline bool is_humongous_reclaim_candidate(uint region); 590 591 // Remove from the reclaim candidate set. Also remove from the 592 // collection set so that later encounters avoid the slow path. 593 inline void set_humongous_is_live(oop obj); 594 595 // Register the given region to be part of the collection set. 596 inline void register_humongous_region_with_cset(uint index); 597 // Register regions with humongous objects (actually on the start region) in 598 // the in_cset_fast_test table. 599 void register_humongous_regions_with_cset(); 600 // We register a region with the fast "in collection set" test. We 601 // simply set to true the array slot corresponding to this region. 602 void register_young_region_with_cset(HeapRegion* r) { 603 _in_cset_fast_test.set_in_young(r->hrm_index()); 604 } 605 void register_old_region_with_cset(HeapRegion* r) { 606 _in_cset_fast_test.set_in_old(r->hrm_index()); 607 } 608 inline void register_ext_region_with_cset(HeapRegion* r) { 609 _in_cset_fast_test.set_ext(r->hrm_index()); 610 } 611 void clear_in_cset(const HeapRegion* hr) { 612 _in_cset_fast_test.clear(hr); 613 } 614 615 void clear_cset_fast_test() { 616 _in_cset_fast_test.clear(); 617 } 618 619 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 620 621 // This is called at the start of either a concurrent cycle or a Full 622 // GC to update the number of old marking cycles started. 623 void increment_old_marking_cycles_started(); 624 625 // This is called at the end of either a concurrent cycle or a Full 626 // GC to update the number of old marking cycles completed. Those two 627 // can happen in a nested fashion, i.e., we start a concurrent 628 // cycle, a Full GC happens half-way through it which ends first, 629 // and then the cycle notices that a Full GC happened and ends 630 // too. The concurrent parameter is a boolean to help us do a bit 631 // tighter consistency checking in the method. If concurrent is 632 // false, the caller is the inner caller in the nesting (i.e., the 633 // Full GC). If concurrent is true, the caller is the outer caller 634 // in this nesting (i.e., the concurrent cycle). Further nesting is 635 // not currently supported. The end of this call also notifies 636 // the FullGCCount_lock in case a Java thread is waiting for a full 637 // GC to happen (e.g., it called System.gc() with 638 // +ExplicitGCInvokesConcurrent). 639 void increment_old_marking_cycles_completed(bool concurrent); 640 641 uint old_marking_cycles_completed() { 642 return _old_marking_cycles_completed; 643 } 644 645 G1HRPrinter* hr_printer() { return &_hr_printer; } 646 647 // Allocates a new heap region instance. 648 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 649 650 // Allocate the highest free region in the reserved heap. This will commit 651 // regions as necessary. 652 HeapRegion* alloc_highest_free_region(); 653 654 // Frees a non-humongous region by initializing its contents and 655 // adding it to the free list that's passed as a parameter (this is 656 // usually a local list which will be appended to the master free 657 // list later). The used bytes of freed regions are accumulated in 658 // pre_used. If skip_remset is true, the region's RSet will not be freed 659 // up. If skip_hot_card_cache is true, the region's hot card cache will not 660 // be freed up. The assumption is that this will be done later. 661 // The locked parameter indicates if the caller has already taken 662 // care of proper synchronization. This may allow some optimizations. 663 void free_region(HeapRegion* hr, 664 FreeRegionList* free_list, 665 bool skip_remset, 666 bool skip_hot_card_cache = false, 667 bool locked = false); 668 669 // It dirties the cards that cover the block so that the post 670 // write barrier never queues anything when updating objects on this 671 // block. It is assumed (and in fact we assert) that the block 672 // belongs to a young region. 673 inline void dirty_young_block(HeapWord* start, size_t word_size); 674 675 // Frees a humongous region by collapsing it into individual regions 676 // and calling free_region() for each of them. The freed regions 677 // will be added to the free list that's passed as a parameter (this 678 // is usually a local list which will be appended to the master free 679 // list later). The used bytes of freed regions are accumulated in 680 // pre_used. If skip_remset is true, the region's RSet will not be freed 681 // up. The assumption is that this will be done later. 682 void free_humongous_region(HeapRegion* hr, 683 FreeRegionList* free_list, 684 bool skip_remset); 685 686 // Facility for allocating in 'archive' regions in high heap memory and 687 // recording the allocated ranges. These should all be called from the 688 // VM thread at safepoints, without the heap lock held. They can be used 689 // to create and archive a set of heap regions which can be mapped at the 690 // same fixed addresses in a subsequent JVM invocation. 691 void begin_archive_alloc_range(); 692 693 // Check if the requested size would be too large for an archive allocation. 694 bool is_archive_alloc_too_large(size_t word_size); 695 696 // Allocate memory of the requested size from the archive region. This will 697 // return NULL if the size is too large or if no memory is available. It 698 // does not trigger a garbage collection. 699 HeapWord* archive_mem_allocate(size_t word_size); 700 701 // Optionally aligns the end address and returns the allocated ranges in 702 // an array of MemRegions in order of ascending addresses. 703 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 704 size_t end_alignment_in_bytes = 0); 705 706 // Facility for allocating a fixed range within the heap and marking 707 // the containing regions as 'archive'. For use at JVM init time, when the 708 // caller may mmap archived heap data at the specified range(s). 709 // Verify that the MemRegions specified in the argument array are within the 710 // reserved heap. 711 bool check_archive_addresses(MemRegion* range, size_t count); 712 713 // Commit the appropriate G1 regions containing the specified MemRegions 714 // and mark them as 'archive' regions. The regions in the array must be 715 // non-overlapping and in order of ascending address. 716 bool alloc_archive_regions(MemRegion* range, size_t count); 717 718 // Insert any required filler objects in the G1 regions around the specified 719 // ranges to make the regions parseable. This must be called after 720 // alloc_archive_regions, and after class loading has occurred. 721 void fill_archive_regions(MemRegion* range, size_t count); 722 723 // For each of the specified MemRegions, uncommit the containing G1 regions 724 // which had been allocated by alloc_archive_regions. This should be called 725 // rather than fill_archive_regions at JVM init time if the archive file 726 // mapping failed, with the same non-overlapping and sorted MemRegion array. 727 void dealloc_archive_regions(MemRegion* range, size_t count); 728 729 protected: 730 731 // Shrink the garbage-first heap by at most the given size (in bytes!). 732 // (Rounds down to a HeapRegion boundary.) 733 virtual void shrink(size_t expand_bytes); 734 void shrink_helper(size_t expand_bytes); 735 736 #if TASKQUEUE_STATS 737 static void print_taskqueue_stats_hdr(outputStream* const st); 738 void print_taskqueue_stats() const; 739 void reset_taskqueue_stats(); 740 #endif // TASKQUEUE_STATS 741 742 // Schedule the VM operation that will do an evacuation pause to 743 // satisfy an allocation request of word_size. *succeeded will 744 // return whether the VM operation was successful (it did do an 745 // evacuation pause) or not (another thread beat us to it or the GC 746 // locker was active). Given that we should not be holding the 747 // Heap_lock when we enter this method, we will pass the 748 // gc_count_before (i.e., total_collections()) as a parameter since 749 // it has to be read while holding the Heap_lock. Currently, both 750 // methods that call do_collection_pause() release the Heap_lock 751 // before the call, so it's easy to read gc_count_before just before. 752 HeapWord* do_collection_pause(size_t word_size, 753 uint gc_count_before, 754 bool* succeeded, 755 GCCause::Cause gc_cause); 756 757 void wait_for_root_region_scanning(); 758 759 // The guts of the incremental collection pause, executed by the vm 760 // thread. It returns false if it is unable to do the collection due 761 // to the GC locker being active, true otherwise 762 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 763 764 // Actually do the work of evacuating the collection set. 765 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states); 766 767 void pre_evacuate_collection_set(); 768 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 769 770 // Print the header for the per-thread termination statistics. 771 static void print_termination_stats_hdr(); 772 // Print actual per-thread termination statistics. 773 void print_termination_stats(uint worker_id, 774 double elapsed_ms, 775 double strong_roots_ms, 776 double term_ms, 777 size_t term_attempts, 778 size_t alloc_buffer_waste, 779 size_t undo_waste) const; 780 // Update object copying statistics. 781 void record_obj_copy_mem_stats(); 782 783 // The hot card cache for remembered set insertion optimization. 784 G1HotCardCache* _hot_card_cache; 785 786 // The g1 remembered set of the heap. 787 G1RemSet* _g1_rem_set; 788 789 // A set of cards that cover the objects for which the Rsets should be updated 790 // concurrently after the collection. 791 DirtyCardQueueSet _dirty_card_queue_set; 792 793 // The closure used to refine a single card. 794 RefineCardTableEntryClosure* _refine_cte_cl; 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 ConcurrentG1Refine* _cg1r; 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 STWGCTimer* _gc_timer_stw; 919 920 G1NewTracer* _gc_tracer_stw; 921 922 // During reference object discovery, the _is_alive_non_header 923 // closure (if non-null) is applied to the referent object to 924 // determine whether the referent is live. If so then the 925 // reference object does not need to be 'discovered' and can 926 // be treated as a regular oop. This has the benefit of reducing 927 // the number of 'discovered' reference objects that need to 928 // be processed. 929 // 930 // Instance of the is_alive closure for embedding into the 931 // STW reference processor as the _is_alive_non_header field. 932 // Supplying a value for the _is_alive_non_header field is 933 // optional but doing so prevents unnecessary additions to 934 // the discovered lists during reference discovery. 935 G1STWIsAliveClosure _is_alive_closure_stw; 936 937 // The (concurrent marking) reference processor... 938 ReferenceProcessor* _ref_processor_cm; 939 940 // Instance of the concurrent mark is_alive closure for embedding 941 // into the Concurrent Marking reference processor as the 942 // _is_alive_non_header field. Supplying a value for the 943 // _is_alive_non_header field is optional but doing so prevents 944 // unnecessary additions to the discovered lists during reference 945 // discovery. 946 G1CMIsAliveClosure _is_alive_closure_cm; 947 948 volatile bool _free_regions_coming; 949 950 public: 951 952 void set_refine_cte_cl_concurrency(bool concurrent); 953 954 RefToScanQueue *task_queue(uint i) const; 955 956 uint num_task_queues() const; 957 958 // A set of cards where updates happened during the GC 959 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 960 961 // Create a G1CollectedHeap with the specified policy. 962 // Must call the initialize method afterwards. 963 // May not return if something goes wrong. 964 G1CollectedHeap(G1CollectorPolicy* policy); 965 966 // Initialize the G1CollectedHeap to have the initial and 967 // maximum sizes and remembered and barrier sets 968 // specified by the policy object. 969 jint initialize(); 970 971 virtual void stop(); 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 // The rem set and barrier set. 1005 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1006 1007 // Try to minimize the remembered set. 1008 void scrub_rem_set(); 1009 1010 uint get_gc_time_stamp() { 1011 return _gc_time_stamp; 1012 } 1013 1014 inline void reset_gc_time_stamp(); 1015 1016 void check_gc_time_stamps() PRODUCT_RETURN; 1017 1018 inline void increment_gc_time_stamp(); 1019 1020 // Reset the given region's GC timestamp. If it's starts humongous, 1021 // also reset the GC timestamp of its corresponding 1022 // continues humongous regions too. 1023 void reset_gc_time_stamps(HeapRegion* hr); 1024 1025 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 1026 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i); 1027 1028 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. 1029 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i); 1030 1031 // The shared block offset table array. 1032 G1BlockOffsetTable* bot() const { return _bot; } 1033 1034 // Reference Processing accessors 1035 1036 // The STW reference processor.... 1037 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1038 1039 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1040 1041 // The Concurrent Marking reference processor... 1042 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1043 1044 virtual size_t capacity() const; 1045 virtual size_t used() const; 1046 // This should be called when we're not holding the heap lock. The 1047 // result might be a bit inaccurate. 1048 size_t used_unlocked() const; 1049 size_t recalculate_used() const; 1050 1051 // These virtual functions do the actual allocation. 1052 // Some heaps may offer a contiguous region for shared non-blocking 1053 // allocation, via inlined code (by exporting the address of the top and 1054 // end fields defining the extent of the contiguous allocation region.) 1055 // But G1CollectedHeap doesn't yet support this. 1056 1057 virtual bool is_maximal_no_gc() const { 1058 return _hrm.available() == 0; 1059 } 1060 1061 // The current number of regions in the heap. 1062 uint num_regions() const { return _hrm.length(); } 1063 1064 // The max number of regions in the heap. 1065 uint max_regions() const { return _hrm.max_length(); } 1066 1067 // The number of regions that are completely free. 1068 uint num_free_regions() const { return _hrm.num_free_regions(); } 1069 1070 MemoryUsage get_auxiliary_data_memory_usage() const { 1071 return _hrm.get_auxiliary_data_memory_usage(); 1072 } 1073 1074 // The number of regions that are not completely free. 1075 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1076 1077 #ifdef ASSERT 1078 bool is_on_master_free_list(HeapRegion* hr) { 1079 return _hrm.is_free(hr); 1080 } 1081 #endif // ASSERT 1082 1083 // Wrapper for the region list operations that can be called from 1084 // methods outside this class. 1085 1086 void secondary_free_list_add(FreeRegionList* list) { 1087 _secondary_free_list.add_ordered(list); 1088 } 1089 1090 void append_secondary_free_list() { 1091 _hrm.insert_list_into_free_list(&_secondary_free_list); 1092 } 1093 1094 void append_secondary_free_list_if_not_empty_with_lock() { 1095 // If the secondary free list looks empty there's no reason to 1096 // take the lock and then try to append it. 1097 if (!_secondary_free_list.is_empty()) { 1098 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1099 append_secondary_free_list(); 1100 } 1101 } 1102 1103 inline void old_set_add(HeapRegion* hr); 1104 inline void old_set_remove(HeapRegion* hr); 1105 1106 size_t non_young_capacity_bytes() { 1107 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes; 1108 } 1109 1110 void set_free_regions_coming(); 1111 void reset_free_regions_coming(); 1112 bool free_regions_coming() { return _free_regions_coming; } 1113 void wait_while_free_regions_coming(); 1114 1115 // Determine whether the given region is one that we are using as an 1116 // old GC alloc region. 1117 bool is_old_gc_alloc_region(HeapRegion* hr); 1118 1119 // Perform a collection of the heap; intended for use in implementing 1120 // "System.gc". This probably implies as full a collection as the 1121 // "CollectedHeap" supports. 1122 virtual void collect(GCCause::Cause cause); 1123 1124 virtual bool copy_allocation_context_stats(const jint* contexts, 1125 jlong* totals, 1126 jbyte* accuracy, 1127 jint len); 1128 1129 // True iff an evacuation has failed in the most-recent collection. 1130 bool evacuation_failed() { return _evacuation_failed; } 1131 1132 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed); 1133 void prepend_to_freelist(FreeRegionList* list); 1134 void decrement_summary_bytes(size_t bytes); 1135 1136 virtual bool is_in(const void* p) const; 1137 #ifdef ASSERT 1138 // Returns whether p is in one of the available areas of the heap. Slow but 1139 // extensive version. 1140 bool is_in_exact(const void* p) const; 1141 #endif 1142 1143 // Return "TRUE" iff the given object address is within the collection 1144 // set. Assumes that the reference points into the heap. 1145 inline bool is_in_cset(const HeapRegion *hr); 1146 inline bool is_in_cset(oop obj); 1147 1148 inline bool is_in_cset_or_humongous(const oop obj); 1149 1150 private: 1151 // This array is used for a quick test on whether a reference points into 1152 // the collection set or not. Each of the array's elements denotes whether the 1153 // corresponding region is in the collection set or not. 1154 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1155 1156 public: 1157 1158 inline InCSetState in_cset_state(const oop obj); 1159 1160 // Return "TRUE" iff the given object address is in the reserved 1161 // region of g1. 1162 bool is_in_g1_reserved(const void* p) const { 1163 return _hrm.reserved().contains(p); 1164 } 1165 1166 // Returns a MemRegion that corresponds to the space that has been 1167 // reserved for the heap 1168 MemRegion g1_reserved() const { 1169 return _hrm.reserved(); 1170 } 1171 1172 virtual bool is_in_closed_subset(const void* p) const; 1173 1174 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1175 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set()); 1176 } 1177 1178 // Iteration functions. 1179 1180 // Iterate over all objects, calling "cl.do_object" on each. 1181 virtual void object_iterate(ObjectClosure* cl); 1182 1183 virtual void safe_object_iterate(ObjectClosure* cl) { 1184 object_iterate(cl); 1185 } 1186 1187 // Iterate over heap regions, in address order, terminating the 1188 // iteration early if the "doHeapRegion" method returns "true". 1189 void heap_region_iterate(HeapRegionClosure* blk) const; 1190 1191 // Return the region with the given index. It assumes the index is valid. 1192 inline HeapRegion* region_at(uint index) const; 1193 1194 // Return the next region (by index) that is part of the same 1195 // humongous object that hr is part of. 1196 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1197 1198 // Calculate the region index of the given address. Given address must be 1199 // within the heap. 1200 inline uint addr_to_region(HeapWord* addr) const; 1201 1202 inline HeapWord* bottom_addr_for_region(uint index) const; 1203 1204 // Iterate over the heap regions in parallel. Assumes that this will be called 1205 // in parallel by ParallelGCThreads worker threads with distinct worker ids 1206 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion" 1207 // to each of the regions, by attempting to claim the region using the 1208 // HeapRegionClaimer and, if successful, applying the closure to the claimed 1209 // region. The concurrent argument should be set to true if iteration is 1210 // performed concurrently, during which no assumptions are made for consistent 1211 // attributes of the heap regions (as they might be modified while iterating). 1212 void heap_region_par_iterate(HeapRegionClosure* cl, 1213 uint worker_id, 1214 HeapRegionClaimer* hrclaimer, 1215 bool concurrent = false) const; 1216 1217 // Iterate over the regions (if any) in the current collection set. 1218 void collection_set_iterate(HeapRegionClosure* blk); 1219 1220 // Iterate over the regions (if any) in the current collection set. Starts the 1221 // iteration over the entire collection set so that the start regions of a given 1222 // worker id over the set active_workers are evenly spread across the set of 1223 // collection set regions. 1224 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id); 1225 1226 HeapRegion* next_compaction_region(const HeapRegion* from) const; 1227 1228 // Returns the HeapRegion that contains addr. addr must not be NULL. 1229 template <class T> 1230 inline HeapRegion* heap_region_containing(const T addr) const; 1231 1232 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1233 // each address in the (reserved) heap is a member of exactly 1234 // one block. The defining characteristic of a block is that it is 1235 // possible to find its size, and thus to progress forward to the next 1236 // block. (Blocks may be of different sizes.) Thus, blocks may 1237 // represent Java objects, or they might be free blocks in a 1238 // free-list-based heap (or subheap), as long as the two kinds are 1239 // distinguishable and the size of each is determinable. 1240 1241 // Returns the address of the start of the "block" that contains the 1242 // address "addr". We say "blocks" instead of "object" since some heaps 1243 // may not pack objects densely; a chunk may either be an object or a 1244 // non-object. 1245 virtual HeapWord* block_start(const void* addr) const; 1246 1247 // Requires "addr" to be the start of a chunk, and returns its size. 1248 // "addr + size" is required to be the start of a new chunk, or the end 1249 // of the active area of the heap. 1250 virtual size_t block_size(const HeapWord* addr) const; 1251 1252 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1253 // the block is an object. 1254 virtual bool block_is_obj(const HeapWord* addr) const; 1255 1256 // Section on thread-local allocation buffers (TLABs) 1257 // See CollectedHeap for semantics. 1258 1259 bool supports_tlab_allocation() const; 1260 size_t tlab_capacity(Thread* ignored) const; 1261 size_t tlab_used(Thread* ignored) const; 1262 size_t max_tlab_size() const; 1263 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1264 1265 // Can a compiler initialize a new object without store barriers? 1266 // This permission only extends from the creation of a new object 1267 // via a TLAB up to the first subsequent safepoint. If such permission 1268 // is granted for this heap type, the compiler promises to call 1269 // defer_store_barrier() below on any slow path allocation of 1270 // a new object for which such initializing store barriers will 1271 // have been elided. G1, like CMS, allows this, but should be 1272 // ready to provide a compensating write barrier as necessary 1273 // if that storage came out of a non-young region. The efficiency 1274 // of this implementation depends crucially on being able to 1275 // answer very efficiently in constant time whether a piece of 1276 // storage in the heap comes from a young region or not. 1277 // See ReduceInitialCardMarks. 1278 virtual bool can_elide_tlab_store_barriers() const { 1279 return true; 1280 } 1281 1282 virtual bool card_mark_must_follow_store() const { 1283 return true; 1284 } 1285 1286 inline bool is_in_young(const oop obj); 1287 1288 virtual bool is_scavengable(const void* addr); 1289 1290 // We don't need barriers for initializing stores to objects 1291 // in the young gen: for the SATB pre-barrier, there is no 1292 // pre-value that needs to be remembered; for the remembered-set 1293 // update logging post-barrier, we don't maintain remembered set 1294 // information for young gen objects. 1295 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1296 1297 // Returns "true" iff the given word_size is "very large". 1298 static bool is_humongous(size_t word_size) { 1299 // Note this has to be strictly greater-than as the TLABs 1300 // are capped at the humongous threshold and we want to 1301 // ensure that we don't try to allocate a TLAB as 1302 // humongous and that we don't allocate a humongous 1303 // object in a TLAB. 1304 return word_size > _humongous_object_threshold_in_words; 1305 } 1306 1307 // Returns the humongous threshold for a specific region size 1308 static size_t humongous_threshold_for(size_t region_size) { 1309 return (region_size / 2); 1310 } 1311 1312 // Returns the number of regions the humongous object of the given word size 1313 // requires. 1314 static size_t humongous_obj_size_in_regions(size_t word_size); 1315 1316 // Print the maximum heap capacity. 1317 virtual size_t max_capacity() const; 1318 1319 virtual jlong millis_since_last_gc(); 1320 1321 1322 // Convenience function to be used in situations where the heap type can be 1323 // asserted to be this type. 1324 static G1CollectedHeap* heap(); 1325 1326 void set_region_short_lived_locked(HeapRegion* hr); 1327 // add appropriate methods for any other surv rate groups 1328 1329 const G1SurvivorRegions* survivor() const { return &_survivor; } 1330 1331 uint survivor_regions_count() const { 1332 return _survivor.length(); 1333 } 1334 1335 uint eden_regions_count() const { 1336 return _eden.length(); 1337 } 1338 1339 uint young_regions_count() const { 1340 return _eden.length() + _survivor.length(); 1341 } 1342 1343 uint old_regions_count() const { return _old_set.length(); } 1344 1345 uint humongous_regions_count() const { return _humongous_set.length(); } 1346 1347 #ifdef ASSERT 1348 bool check_young_list_empty(); 1349 #endif 1350 1351 // *** Stuff related to concurrent marking. It's not clear to me that so 1352 // many of these need to be public. 1353 1354 // The functions below are helper functions that a subclass of 1355 // "CollectedHeap" can use in the implementation of its virtual 1356 // functions. 1357 // This performs a concurrent marking of the live objects in a 1358 // bitmap off to the side. 1359 void doConcurrentMark(); 1360 1361 bool isMarkedNext(oop obj) const; 1362 1363 // Determine if an object is dead, given the object and also 1364 // the region to which the object belongs. An object is dead 1365 // iff a) it was not allocated since the last mark, b) it 1366 // is not marked, and c) it is not in an archive region. 1367 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1368 return 1369 hr->is_obj_dead(obj, _cm->prevMarkBitMap()) && 1370 !hr->is_archive(); 1371 } 1372 1373 // This function returns true when an object has been 1374 // around since the previous marking and hasn't yet 1375 // been marked during this marking, and is not in an archive region. 1376 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1377 return 1378 !hr->obj_allocated_since_next_marking(obj) && 1379 !isMarkedNext(obj) && 1380 !hr->is_archive(); 1381 } 1382 1383 // Determine if an object is dead, given only the object itself. 1384 // This will find the region to which the object belongs and 1385 // then call the region version of the same function. 1386 1387 // Added if it is NULL it isn't dead. 1388 1389 inline bool is_obj_dead(const oop obj) const; 1390 1391 inline bool is_obj_ill(const oop obj) const; 1392 1393 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1394 1395 // Refinement 1396 1397 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1398 1399 // Optimized nmethod scanning support routines 1400 1401 // Register the given nmethod with the G1 heap. 1402 virtual void register_nmethod(nmethod* nm); 1403 1404 // Unregister the given nmethod from the G1 heap. 1405 virtual void unregister_nmethod(nmethod* nm); 1406 1407 // Free up superfluous code root memory. 1408 void purge_code_root_memory(); 1409 1410 // Rebuild the strong code root lists for each region 1411 // after a full GC. 1412 void rebuild_strong_code_roots(); 1413 1414 // Partial cleaning used when class unloading is disabled. 1415 // Let the caller choose what structures to clean out: 1416 // - StringTable 1417 // - SymbolTable 1418 // - StringDeduplication structures 1419 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup); 1420 1421 // Complete cleaning used when class unloading is enabled. 1422 // Cleans out all structures handled by partial_cleaning and also the CodeCache. 1423 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); 1424 1425 // Redirty logged cards in the refinement queue. 1426 void redirty_logged_cards(); 1427 // Verification 1428 1429 // Perform any cleanup actions necessary before allowing a verification. 1430 virtual void prepare_for_verify(); 1431 1432 // Perform verification. 1433 1434 // vo == UsePrevMarking -> use "prev" marking information, 1435 // vo == UseNextMarking -> use "next" marking information 1436 // vo == UseMarkWord -> use the mark word in the object header 1437 // 1438 // NOTE: Only the "prev" marking information is guaranteed to be 1439 // consistent most of the time, so most calls to this should use 1440 // vo == UsePrevMarking. 1441 // Currently, there is only one case where this is called with 1442 // vo == UseNextMarking, which is to verify the "next" marking 1443 // information at the end of remark. 1444 // Currently there is only one place where this is called with 1445 // vo == UseMarkWord, which is to verify the marking during a 1446 // full GC. 1447 void verify(VerifyOption vo); 1448 1449 // WhiteBox testing support. 1450 virtual bool supports_concurrent_phase_control() const; 1451 virtual const char* const* concurrent_phases() const; 1452 virtual bool request_concurrent_phase(const char* phase); 1453 1454 // The methods below are here for convenience and dispatch the 1455 // appropriate method depending on value of the given VerifyOption 1456 // parameter. The values for that parameter, and their meanings, 1457 // are the same as those above. 1458 1459 bool is_obj_dead_cond(const oop obj, 1460 const HeapRegion* hr, 1461 const VerifyOption vo) const; 1462 1463 bool is_obj_dead_cond(const oop obj, 1464 const VerifyOption vo) const; 1465 1466 G1HeapSummary create_g1_heap_summary(); 1467 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1468 1469 // Printing 1470 private: 1471 void print_heap_regions() const; 1472 void print_regions_on(outputStream* st) const; 1473 1474 public: 1475 virtual void print_on(outputStream* st) const; 1476 virtual void print_extended_on(outputStream* st) const; 1477 virtual void print_on_error(outputStream* st) const; 1478 1479 virtual void print_gc_threads_on(outputStream* st) const; 1480 virtual void gc_threads_do(ThreadClosure* tc) const; 1481 1482 // Override 1483 void print_tracing_info() const; 1484 1485 // The following two methods are helpful for debugging RSet issues. 1486 void print_cset_rsets() PRODUCT_RETURN; 1487 void print_all_rsets() PRODUCT_RETURN; 1488 1489 public: 1490 size_t pending_card_num(); 1491 1492 protected: 1493 size_t _max_heap_capacity; 1494 }; 1495 1496 class G1ParEvacuateFollowersClosure : public VoidClosure { 1497 private: 1498 double _start_term; 1499 double _term_time; 1500 size_t _term_attempts; 1501 1502 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 1503 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 1504 protected: 1505 G1CollectedHeap* _g1h; 1506 G1ParScanThreadState* _par_scan_state; 1507 RefToScanQueueSet* _queues; 1508 ParallelTaskTerminator* _terminator; 1509 1510 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 1511 RefToScanQueueSet* queues() { return _queues; } 1512 ParallelTaskTerminator* terminator() { return _terminator; } 1513 1514 public: 1515 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 1516 G1ParScanThreadState* par_scan_state, 1517 RefToScanQueueSet* queues, 1518 ParallelTaskTerminator* terminator) 1519 : _g1h(g1h), _par_scan_state(par_scan_state), 1520 _queues(queues), _terminator(terminator), 1521 _start_term(0.0), _term_time(0.0), _term_attempts(0) {} 1522 1523 void do_void(); 1524 1525 double term_time() const { return _term_time; } 1526 size_t term_attempts() const { return _term_attempts; } 1527 1528 private: 1529 inline bool offer_termination(); 1530 }; 1531 1532 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP