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/hSpaceCounters.hpp" 46 #include "gc/g1/heapRegionManager.hpp" 47 #include "gc/g1/heapRegionSet.hpp" 48 #include "gc/shared/barrierSet.hpp" 49 #include "gc/shared/collectedHeap.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 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 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 RefineCardTableEntryClosure; 115 116 class G1RegionMappingChangedListener : public G1MappingChangedListener { 117 private: 118 void reset_from_card_cache(uint start_idx, size_t num_regions); 119 public: 120 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 121 }; 122 123 class G1CollectedHeap : public CollectedHeap { 124 friend class G1FreeCollectionSetTask; 125 friend class VM_CollectForMetadataAllocation; 126 friend class VM_G1CollectForAllocation; 127 friend class VM_G1CollectFull; 128 friend class VM_G1IncCollectionPause; 129 friend class VMStructs; 130 friend class MutatorAllocRegion; 131 friend class G1GCAllocRegion; 132 friend class G1HeapVerifier; 133 134 // Closures used in implementation. 135 friend class G1ParScanThreadState; 136 friend class G1ParScanThreadStateSet; 137 friend class G1ParTask; 138 friend class G1PLABAllocator; 139 friend class G1PrepareCompactClosure; 140 141 // Other related classes. 142 friend class HeapRegionClaimerBase; 143 144 // Testing classes. 145 friend class G1CheckCSetFastTableClosure; 146 147 private: 148 WorkGang* _workers; 149 G1CollectorPolicy* _collector_policy; 150 151 static size_t _humongous_object_threshold_in_words; 152 153 // The secondary free list which contains regions that have been 154 // freed up during the cleanup process. This will be appended to 155 // the master free list when appropriate. 156 FreeRegionList _secondary_free_list; 157 158 // It keeps track of the old regions. 159 HeapRegionSet _old_set; 160 161 // It keeps track of the humongous regions. 162 HeapRegionSet _humongous_set; 163 164 void eagerly_reclaim_humongous_regions(); 165 // Start a new incremental collection set for the next pause. 166 void start_new_collection_set(); 167 168 // The number of regions we could create by expansion. 169 uint _expansion_regions; 170 171 // The block offset table for the G1 heap. 172 G1BlockOffsetTable* _bot; 173 174 // Tears down the region sets / lists so that they are empty and the 175 // regions on the heap do not belong to a region set / list. The 176 // only exception is the humongous set which we leave unaltered. If 177 // free_list_only is true, it will only tear down the master free 178 // list. It is called before a Full GC (free_list_only == false) or 179 // before heap shrinking (free_list_only == true). 180 void tear_down_region_sets(bool free_list_only); 181 182 // Rebuilds the region sets / lists so that they are repopulated to 183 // reflect the contents of the heap. The only exception is the 184 // humongous set which was not torn down in the first place. If 185 // free_list_only is true, it will only rebuild the master free 186 // list. It is called after a Full GC (free_list_only == false) or 187 // after heap shrinking (free_list_only == true). 188 void rebuild_region_sets(bool free_list_only); 189 190 // Callback for region mapping changed events. 191 G1RegionMappingChangedListener _listener; 192 193 // The sequence of all heap regions in the heap. 194 HeapRegionManager _hrm; 195 196 // Manages all allocations with regions except humongous object allocations. 197 G1Allocator* _allocator; 198 199 // Manages all heap verification. 200 G1HeapVerifier* _verifier; 201 202 // Outside of GC pauses, the number of bytes used in all regions other 203 // than the current allocation region(s). 204 size_t _summary_bytes_used; 205 206 void increase_used(size_t bytes); 207 void decrease_used(size_t bytes); 208 209 void set_used(size_t bytes); 210 211 // Class that handles archive allocation ranges. 212 G1ArchiveAllocator* _archive_allocator; 213 214 // Statistics for each allocation context 215 AllocationContextStats _allocation_context_stats; 216 217 // GC allocation statistics policy for survivors. 218 G1EvacStats _survivor_evac_stats; 219 220 // GC allocation statistics policy for tenured objects. 221 G1EvacStats _old_evac_stats; 222 223 // It specifies whether we should attempt to expand the heap after a 224 // region allocation failure. If heap expansion fails we set this to 225 // false so that we don't re-attempt the heap expansion (it's likely 226 // that subsequent expansion attempts will also fail if one fails). 227 // Currently, it is only consulted during GC and it's reset at the 228 // start of each GC. 229 bool _expand_heap_after_alloc_failure; 230 231 // Helper for monitoring and management support. 232 G1MonitoringSupport* _g1mm; 233 234 // Records whether the region at the given index is (still) a 235 // candidate for eager reclaim. Only valid for humongous start 236 // regions; other regions have unspecified values. Humongous start 237 // regions are initialized at start of collection pause, with 238 // candidates removed from the set as they are found reachable from 239 // roots or the young generation. 240 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 241 protected: 242 bool default_value() const { return false; } 243 public: 244 void clear() { G1BiasedMappedArray<bool>::clear(); } 245 void set_candidate(uint region, bool value) { 246 set_by_index(region, value); 247 } 248 bool is_candidate(uint region) { 249 return get_by_index(region); 250 } 251 }; 252 253 HumongousReclaimCandidates _humongous_reclaim_candidates; 254 // Stores whether during humongous object registration we found candidate regions. 255 // If not, we can skip a few steps. 256 bool _has_humongous_reclaim_candidates; 257 258 volatile uint _gc_time_stamp; 259 260 G1HRPrinter _hr_printer; 261 262 // It decides whether an explicit GC should start a concurrent cycle 263 // instead of doing a STW GC. Currently, a concurrent cycle is 264 // explicitly started if: 265 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 266 // (b) cause == _g1_humongous_allocation 267 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 268 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 269 // (e) cause == _update_allocation_context_stats_inc 270 // (f) cause == _wb_conc_mark 271 bool should_do_concurrent_full_gc(GCCause::Cause cause); 272 273 // indicates whether we are in young or mixed GC mode 274 G1CollectorState _collector_state; 275 276 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 277 // concurrent cycles) we have started. 278 volatile uint _old_marking_cycles_started; 279 280 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 281 // concurrent cycles) we have completed. 282 volatile uint _old_marking_cycles_completed; 283 284 // This is a non-product method that is helpful for testing. It is 285 // called at the end of a GC and artificially expands the heap by 286 // allocating a number of dead regions. This way we can induce very 287 // frequent marking cycles and stress the cleanup / concurrent 288 // cleanup code more (as all the regions that will be allocated by 289 // this method will be found dead by the marking cycle). 290 void allocate_dummy_regions() PRODUCT_RETURN; 291 292 // Clear RSets after a compaction. It also resets the GC time stamps. 293 void clear_rsets_post_compaction(); 294 295 // If the HR printer is active, dump the state of the regions in the 296 // heap after a compaction. 297 void print_hrm_post_compaction(); 298 299 // Create a memory mapper for auxiliary data structures of the given size and 300 // translation factor. 301 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 302 size_t size, 303 size_t translation_factor); 304 305 static G1Policy* create_g1_policy(); 306 307 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 308 309 void process_weak_jni_handles(); 310 311 // These are macros so that, if the assert fires, we get the correct 312 // line number, file, etc. 313 314 #define heap_locking_asserts_params(_extra_message_) \ 315 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 316 (_extra_message_), \ 317 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 318 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 319 BOOL_TO_STR(Thread::current()->is_VM_thread()) 320 321 #define assert_heap_locked() \ 322 do { \ 323 assert(Heap_lock->owned_by_self(), \ 324 heap_locking_asserts_params("should be holding the Heap_lock")); \ 325 } while (0) 326 327 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 328 do { \ 329 assert(Heap_lock->owned_by_self() || \ 330 (SafepointSynchronize::is_at_safepoint() && \ 331 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 332 heap_locking_asserts_params("should be holding the Heap_lock or " \ 333 "should be at a safepoint")); \ 334 } while (0) 335 336 #define assert_heap_locked_and_not_at_safepoint() \ 337 do { \ 338 assert(Heap_lock->owned_by_self() && \ 339 !SafepointSynchronize::is_at_safepoint(), \ 340 heap_locking_asserts_params("should be holding the Heap_lock and " \ 341 "should not be at a safepoint")); \ 342 } while (0) 343 344 #define assert_heap_not_locked() \ 345 do { \ 346 assert(!Heap_lock->owned_by_self(), \ 347 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 348 } while (0) 349 350 #define assert_heap_not_locked_and_not_at_safepoint() \ 351 do { \ 352 assert(!Heap_lock->owned_by_self() && \ 353 !SafepointSynchronize::is_at_safepoint(), \ 354 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 355 "should not be at a safepoint")); \ 356 } while (0) 357 358 #define assert_at_safepoint(_should_be_vm_thread_) \ 359 do { \ 360 assert(SafepointSynchronize::is_at_safepoint() && \ 361 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 362 heap_locking_asserts_params("should be at a safepoint")); \ 363 } while (0) 364 365 #define assert_not_at_safepoint() \ 366 do { \ 367 assert(!SafepointSynchronize::is_at_safepoint(), \ 368 heap_locking_asserts_params("should not be at a safepoint")); \ 369 } while (0) 370 371 protected: 372 373 // The young region list. 374 G1EdenRegions _eden; 375 G1SurvivorRegions _survivor; 376 377 // The current policy object for the collector. 378 G1Policy* _g1_policy; 379 G1HeapSizingPolicy* _heap_sizing_policy; 380 381 G1CollectionSet _collection_set; 382 383 // This is the second level of trying to allocate a new region. If 384 // new_region() didn't find a region on the free_list, this call will 385 // check whether there's anything available on the 386 // secondary_free_list and/or wait for more regions to appear on 387 // that list, if _free_regions_coming is set. 388 HeapRegion* new_region_try_secondary_free_list(bool is_old); 389 390 // Try to allocate a single non-humongous HeapRegion sufficient for 391 // an allocation of the given word_size. If do_expand is true, 392 // attempt to expand the heap if necessary to satisfy the allocation 393 // request. If the region is to be used as an old region or for a 394 // humongous object, set is_old to true. If not, to false. 395 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 396 397 // Initialize a contiguous set of free regions of length num_regions 398 // and starting at index first so that they appear as a single 399 // humongous region. 400 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 401 uint num_regions, 402 size_t word_size, 403 AllocationContext_t context); 404 405 // Attempt to allocate a humongous object of the given size. Return 406 // NULL if unsuccessful. 407 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 408 409 // The following two methods, allocate_new_tlab() and 410 // mem_allocate(), are the two main entry points from the runtime 411 // into the G1's allocation routines. They have the following 412 // assumptions: 413 // 414 // * They should both be called outside safepoints. 415 // 416 // * They should both be called without holding the Heap_lock. 417 // 418 // * All allocation requests for new TLABs should go to 419 // allocate_new_tlab(). 420 // 421 // * All non-TLAB allocation requests should go to mem_allocate(). 422 // 423 // * If either call cannot satisfy the allocation request using the 424 // current allocating region, they will try to get a new one. If 425 // this fails, they will attempt to do an evacuation pause and 426 // retry the allocation. 427 // 428 // * If all allocation attempts fail, even after trying to schedule 429 // an evacuation pause, allocate_new_tlab() will return NULL, 430 // whereas mem_allocate() will attempt a heap expansion and/or 431 // schedule a Full GC. 432 // 433 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 434 // should never be called with word_size being humongous. All 435 // humongous allocation requests should go to mem_allocate() which 436 // will satisfy them with a special path. 437 438 virtual HeapWord* allocate_new_tlab(size_t word_size); 439 440 virtual HeapWord* mem_allocate(size_t word_size, 441 bool* gc_overhead_limit_was_exceeded); 442 443 // The following three methods take a gc_count_before_ret 444 // parameter which is used to return the GC count if the method 445 // returns NULL. Given that we are required to read the GC count 446 // while holding the Heap_lock, and these paths will take the 447 // Heap_lock at some point, it's easier to get them to read the GC 448 // count while holding the Heap_lock before they return NULL instead 449 // of the caller (namely: mem_allocate()) having to also take the 450 // Heap_lock just to read the GC count. 451 452 // First-level mutator allocation attempt: try to allocate out of 453 // the mutator alloc region without taking the Heap_lock. This 454 // should only be used for non-humongous allocations. 455 inline HeapWord* attempt_allocation(size_t word_size, 456 uint* gc_count_before_ret, 457 uint* gclocker_retry_count_ret); 458 459 // Second-level mutator allocation attempt: take the Heap_lock and 460 // retry the allocation attempt, potentially scheduling a GC 461 // pause. This should only be used for non-humongous allocations. 462 HeapWord* attempt_allocation_slow(size_t word_size, 463 AllocationContext_t context, 464 uint* gc_count_before_ret, 465 uint* gclocker_retry_count_ret); 466 467 // Takes the Heap_lock and attempts a humongous allocation. It can 468 // potentially schedule a GC pause. 469 HeapWord* attempt_allocation_humongous(size_t word_size, 470 uint* gc_count_before_ret, 471 uint* gclocker_retry_count_ret); 472 473 // Allocation attempt that should be called during safepoints (e.g., 474 // at the end of a successful GC). expect_null_mutator_alloc_region 475 // specifies whether the mutator alloc region is expected to be NULL 476 // or not. 477 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 478 AllocationContext_t context, 479 bool expect_null_mutator_alloc_region); 480 481 // These methods are the "callbacks" from the G1AllocRegion class. 482 483 // For mutator alloc regions. 484 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 485 void retire_mutator_alloc_region(HeapRegion* alloc_region, 486 size_t allocated_bytes); 487 488 // For GC alloc regions. 489 bool has_more_regions(InCSetState dest); 490 HeapRegion* new_gc_alloc_region(size_t word_size, InCSetState dest); 491 void retire_gc_alloc_region(HeapRegion* alloc_region, 492 size_t allocated_bytes, InCSetState dest); 493 494 // - if explicit_gc is true, the GC is for a System.gc() etc, 495 // otherwise it's for a failed allocation. 496 // - if clear_all_soft_refs is true, all soft references should be 497 // cleared during the GC. 498 // - it returns false if it is unable to do the collection due to the 499 // GC locker being active, true otherwise. 500 bool do_full_collection(bool explicit_gc, 501 bool clear_all_soft_refs); 502 503 // Callback from VM_G1CollectFull operation, or collect_as_vm_thread. 504 virtual void do_full_collection(bool clear_all_soft_refs); 505 506 // Resize the heap if necessary after a full collection. 507 void resize_if_necessary_after_full_collection(); 508 509 // Callback from VM_G1CollectForAllocation operation. 510 // This function does everything necessary/possible to satisfy a 511 // failed allocation request (including collection, expansion, etc.) 512 HeapWord* satisfy_failed_allocation(size_t word_size, 513 AllocationContext_t context, 514 bool* succeeded); 515 private: 516 // Internal helpers used during full GC to split it up to 517 // increase readability. 518 void do_full_collection_inner(G1FullGCScope* scope); 519 void abort_concurrent_cycle(); 520 void verify_before_full_collection(bool explicit_gc); 521 void prepare_heap_for_full_collection(); 522 void prepare_heap_for_mutators(); 523 void abort_refinement(); 524 void verify_after_full_collection(); 525 void print_heap_after_full_collection(G1HeapTransition* heap_transition); 526 527 // Helper method for satisfy_failed_allocation() 528 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 529 AllocationContext_t context, 530 bool do_gc, 531 bool clear_all_soft_refs, 532 bool expect_null_mutator_alloc_region, 533 bool* gc_succeeded); 534 535 protected: 536 // Attempting to expand the heap sufficiently 537 // to support an allocation of the given "word_size". If 538 // successful, perform the allocation and return the address of the 539 // allocated block, or else "NULL". 540 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 541 542 // Preserve any referents discovered by concurrent marking that have not yet been 543 // copied by the STW pause. 544 void preserve_cm_referents(G1ParScanThreadStateSet* per_thread_states); 545 // Process any reference objects discovered during 546 // an incremental evacuation pause. 547 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 548 549 // Enqueue any remaining discovered references 550 // after processing. 551 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states); 552 553 // Merges the information gathered on a per-thread basis for all worker threads 554 // during GC into global variables. 555 void merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states); 556 public: 557 WorkGang* workers() const { return _workers; } 558 559 G1Allocator* allocator() { 560 return _allocator; 561 } 562 563 G1HeapVerifier* verifier() { 564 return _verifier; 565 } 566 567 G1MonitoringSupport* g1mm() { 568 assert(_g1mm != NULL, "should have been initialized"); 569 return _g1mm; 570 } 571 572 // Expand the garbage-first heap by at least the given size (in bytes!). 573 // Returns true if the heap was expanded by the requested amount; 574 // false otherwise. 575 // (Rounds up to a HeapRegion boundary.) 576 bool expand(size_t expand_bytes, WorkGang* pretouch_workers = NULL, double* expand_time_ms = NULL); 577 578 // Returns the PLAB statistics for a given destination. 579 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 580 581 // Determines PLAB size for a given destination. 582 inline size_t desired_plab_sz(InCSetState dest); 583 584 inline AllocationContextStats& allocation_context_stats(); 585 586 // Do anything common to GC's. 587 void gc_prologue(bool full); 588 void gc_epilogue(bool full); 589 590 // Modify the reclaim candidate set and test for presence. 591 // These are only valid for starts_humongous regions. 592 inline void set_humongous_reclaim_candidate(uint region, bool value); 593 inline bool is_humongous_reclaim_candidate(uint region); 594 595 // Remove from the reclaim candidate set. Also remove from the 596 // collection set so that later encounters avoid the slow path. 597 inline void set_humongous_is_live(oop obj); 598 599 // Register the given region to be part of the collection set. 600 inline void register_humongous_region_with_cset(uint index); 601 // Register regions with humongous objects (actually on the start region) in 602 // the in_cset_fast_test table. 603 void register_humongous_regions_with_cset(); 604 // We register a region with the fast "in collection set" test. We 605 // simply set to true the array slot corresponding to this region. 606 void register_young_region_with_cset(HeapRegion* r) { 607 _in_cset_fast_test.set_in_young(r->hrm_index()); 608 } 609 void register_old_region_with_cset(HeapRegion* r) { 610 _in_cset_fast_test.set_in_old(r->hrm_index()); 611 } 612 inline void register_ext_region_with_cset(HeapRegion* r) { 613 _in_cset_fast_test.set_ext(r->hrm_index()); 614 } 615 void clear_in_cset(const HeapRegion* hr) { 616 _in_cset_fast_test.clear(hr); 617 } 618 619 void clear_cset_fast_test() { 620 _in_cset_fast_test.clear(); 621 } 622 623 bool is_user_requested_concurrent_full_gc(GCCause::Cause cause); 624 625 // This is called at the start of either a concurrent cycle or a Full 626 // GC to update the number of old marking cycles started. 627 void increment_old_marking_cycles_started(); 628 629 // This is called at the end of either a concurrent cycle or a Full 630 // GC to update the number of old marking cycles completed. Those two 631 // can happen in a nested fashion, i.e., we start a concurrent 632 // cycle, a Full GC happens half-way through it which ends first, 633 // and then the cycle notices that a Full GC happened and ends 634 // too. The concurrent parameter is a boolean to help us do a bit 635 // tighter consistency checking in the method. If concurrent is 636 // false, the caller is the inner caller in the nesting (i.e., the 637 // Full GC). If concurrent is true, the caller is the outer caller 638 // in this nesting (i.e., the concurrent cycle). Further nesting is 639 // not currently supported. The end of this call also notifies 640 // the FullGCCount_lock in case a Java thread is waiting for a full 641 // GC to happen (e.g., it called System.gc() with 642 // +ExplicitGCInvokesConcurrent). 643 void increment_old_marking_cycles_completed(bool concurrent); 644 645 uint old_marking_cycles_completed() { 646 return _old_marking_cycles_completed; 647 } 648 649 G1HRPrinter* hr_printer() { return &_hr_printer; } 650 651 // Allocates a new heap region instance. 652 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 653 654 // Allocate the highest free region in the reserved heap. This will commit 655 // regions as necessary. 656 HeapRegion* alloc_highest_free_region(); 657 658 // Frees a non-humongous region by initializing its contents and 659 // adding it to the free list that's passed as a parameter (this is 660 // usually a local list which will be appended to the master free 661 // list later). The used bytes of freed regions are accumulated in 662 // pre_used. If skip_remset is true, the region's RSet will not be freed 663 // up. If skip_hot_card_cache is true, the region's hot card cache will not 664 // be freed up. The assumption is that this will be done later. 665 // The locked parameter indicates if the caller has already taken 666 // care of proper synchronization. This may allow some optimizations. 667 void free_region(HeapRegion* hr, 668 FreeRegionList* free_list, 669 bool skip_remset, 670 bool skip_hot_card_cache = false, 671 bool locked = false); 672 673 // It dirties the cards that cover the block so that the post 674 // write barrier never queues anything when updating objects on this 675 // block. It is assumed (and in fact we assert) that the block 676 // belongs to a young region. 677 inline void dirty_young_block(HeapWord* start, size_t word_size); 678 679 // Frees a humongous region by collapsing it into individual regions 680 // and calling free_region() for each of them. The freed regions 681 // will be added to the free list that's passed as a parameter (this 682 // is usually a local list which will be appended to the master free 683 // list later). The used bytes of freed regions are accumulated in 684 // pre_used. If skip_remset is true, the region's RSet will not be freed 685 // up. The assumption is that this will be done later. 686 void free_humongous_region(HeapRegion* hr, 687 FreeRegionList* free_list, 688 bool skip_remset); 689 690 // Facility for allocating in 'archive' regions in high heap memory and 691 // recording the allocated ranges. These should all be called from the 692 // VM thread at safepoints, without the heap lock held. They can be used 693 // to create and archive a set of heap regions which can be mapped at the 694 // same fixed addresses in a subsequent JVM invocation. 695 void begin_archive_alloc_range(); 696 697 // Check if the requested size would be too large for an archive allocation. 698 bool is_archive_alloc_too_large(size_t word_size); 699 700 // Allocate memory of the requested size from the archive region. This will 701 // return NULL if the size is too large or if no memory is available. It 702 // does not trigger a garbage collection. 703 HeapWord* archive_mem_allocate(size_t word_size); 704 705 // Optionally aligns the end address and returns the allocated ranges in 706 // an array of MemRegions in order of ascending addresses. 707 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 708 size_t end_alignment_in_bytes = 0); 709 710 // Facility for allocating a fixed range within the heap and marking 711 // the containing regions as 'archive'. For use at JVM init time, when the 712 // caller may mmap archived heap data at the specified range(s). 713 // Verify that the MemRegions specified in the argument array are within the 714 // reserved heap. 715 bool check_archive_addresses(MemRegion* range, size_t count); 716 717 // Commit the appropriate G1 regions containing the specified MemRegions 718 // and mark them as 'archive' regions. The regions in the array must be 719 // non-overlapping and in order of ascending address. 720 bool alloc_archive_regions(MemRegion* range, size_t count); 721 722 // Insert any required filler objects in the G1 regions around the specified 723 // ranges to make the regions parseable. This must be called after 724 // alloc_archive_regions, and after class loading has occurred. 725 void fill_archive_regions(MemRegion* range, size_t count); 726 727 // For each of the specified MemRegions, uncommit the containing G1 regions 728 // which had been allocated by alloc_archive_regions. This should be called 729 // rather than fill_archive_regions at JVM init time if the archive file 730 // mapping failed, with the same non-overlapping and sorted MemRegion array. 731 void dealloc_archive_regions(MemRegion* range, size_t count); 732 733 protected: 734 735 // Shrink the garbage-first heap by at most the given size (in bytes!). 736 // (Rounds down to a HeapRegion boundary.) 737 virtual void shrink(size_t expand_bytes); 738 void shrink_helper(size_t expand_bytes); 739 740 #if TASKQUEUE_STATS 741 static void print_taskqueue_stats_hdr(outputStream* const st); 742 void print_taskqueue_stats() const; 743 void reset_taskqueue_stats(); 744 #endif // TASKQUEUE_STATS 745 746 // Schedule the VM operation that will do an evacuation pause to 747 // satisfy an allocation request of word_size. *succeeded will 748 // return whether the VM operation was successful (it did do an 749 // evacuation pause) or not (another thread beat us to it or the GC 750 // locker was active). Given that we should not be holding the 751 // Heap_lock when we enter this method, we will pass the 752 // gc_count_before (i.e., total_collections()) as a parameter since 753 // it has to be read while holding the Heap_lock. Currently, both 754 // methods that call do_collection_pause() release the Heap_lock 755 // before the call, so it's easy to read gc_count_before just before. 756 HeapWord* do_collection_pause(size_t word_size, 757 uint gc_count_before, 758 bool* succeeded, 759 GCCause::Cause gc_cause); 760 761 void wait_for_root_region_scanning(); 762 763 // The guts of the incremental collection pause, executed by the vm 764 // thread. It returns false if it is unable to do the collection due 765 // to the GC locker being active, true otherwise 766 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 767 768 // Actually do the work of evacuating the collection set. 769 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states); 770 771 void pre_evacuate_collection_set(); 772 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 773 774 // Print the header for the per-thread termination statistics. 775 static void print_termination_stats_hdr(); 776 // Print actual per-thread termination statistics. 777 void print_termination_stats(uint worker_id, 778 double elapsed_ms, 779 double strong_roots_ms, 780 double term_ms, 781 size_t term_attempts, 782 size_t alloc_buffer_waste, 783 size_t undo_waste) const; 784 // Update object copying statistics. 785 void record_obj_copy_mem_stats(); 786 787 // The hot card cache for remembered set insertion optimization. 788 G1HotCardCache* _hot_card_cache; 789 790 // The g1 remembered set of the heap. 791 G1RemSet* _g1_rem_set; 792 793 // A set of cards that cover the objects for which the Rsets should be updated 794 // concurrently after the collection. 795 DirtyCardQueueSet _dirty_card_queue_set; 796 797 // The closure used to refine a single card. 798 RefineCardTableEntryClosure* _refine_cte_cl; 799 800 // After a collection pause, convert the regions in the collection set into free 801 // regions. 802 void free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 803 804 // Abandon the current collection set without recording policy 805 // statistics or updating free lists. 806 void abandon_collection_set(G1CollectionSet* collection_set); 807 808 // The concurrent marker (and the thread it runs in.) 809 G1ConcurrentMark* _cm; 810 ConcurrentMarkThread* _cmThread; 811 812 // The concurrent refiner. 813 ConcurrentG1Refine* _cg1r; 814 815 // The parallel task queues 816 RefToScanQueueSet *_task_queues; 817 818 // True iff a evacuation has failed in the current collection. 819 bool _evacuation_failed; 820 821 EvacuationFailedInfo* _evacuation_failed_info_array; 822 823 // Failed evacuations cause some logical from-space objects to have 824 // forwarding pointers to themselves. Reset them. 825 void remove_self_forwarding_pointers(); 826 827 // Restore the objects in the regions in the collection set after an 828 // evacuation failure. 829 void restore_after_evac_failure(); 830 831 PreservedMarksSet _preserved_marks_set; 832 833 // Preserve the mark of "obj", if necessary, in preparation for its mark 834 // word being overwritten with a self-forwarding-pointer. 835 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 836 837 #ifndef PRODUCT 838 // Support for forcing evacuation failures. Analogous to 839 // PromotionFailureALot for the other collectors. 840 841 // Records whether G1EvacuationFailureALot should be in effect 842 // for the current GC 843 bool _evacuation_failure_alot_for_current_gc; 844 845 // Used to record the GC number for interval checking when 846 // determining whether G1EvaucationFailureALot is in effect 847 // for the current GC. 848 size_t _evacuation_failure_alot_gc_number; 849 850 // Count of the number of evacuations between failures. 851 volatile size_t _evacuation_failure_alot_count; 852 853 // Set whether G1EvacuationFailureALot should be in effect 854 // for the current GC (based upon the type of GC and which 855 // command line flags are set); 856 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 857 bool during_initial_mark, 858 bool during_marking); 859 860 inline void set_evacuation_failure_alot_for_current_gc(); 861 862 // Return true if it's time to cause an evacuation failure. 863 inline bool evacuation_should_fail(); 864 865 // Reset the G1EvacuationFailureALot counters. Should be called at 866 // the end of an evacuation pause in which an evacuation failure occurred. 867 inline void reset_evacuation_should_fail(); 868 #endif // !PRODUCT 869 870 // ("Weak") Reference processing support. 871 // 872 // G1 has 2 instances of the reference processor class. One 873 // (_ref_processor_cm) handles reference object discovery 874 // and subsequent processing during concurrent marking cycles. 875 // 876 // The other (_ref_processor_stw) handles reference object 877 // discovery and processing during full GCs and incremental 878 // evacuation pauses. 879 // 880 // During an incremental pause, reference discovery will be 881 // temporarily disabled for _ref_processor_cm and will be 882 // enabled for _ref_processor_stw. At the end of the evacuation 883 // pause references discovered by _ref_processor_stw will be 884 // processed and discovery will be disabled. The previous 885 // setting for reference object discovery for _ref_processor_cm 886 // will be re-instated. 887 // 888 // At the start of marking: 889 // * Discovery by the CM ref processor is verified to be inactive 890 // and it's discovered lists are empty. 891 // * Discovery by the CM ref processor is then enabled. 892 // 893 // At the end of marking: 894 // * Any references on the CM ref processor's discovered 895 // lists are processed (possibly MT). 896 // 897 // At the start of full GC we: 898 // * Disable discovery by the CM ref processor and 899 // empty CM ref processor's discovered lists 900 // (without processing any entries). 901 // * Verify that the STW ref processor is inactive and it's 902 // discovered lists are empty. 903 // * Temporarily set STW ref processor discovery as single threaded. 904 // * Temporarily clear the STW ref processor's _is_alive_non_header 905 // field. 906 // * Finally enable discovery by the STW ref processor. 907 // 908 // The STW ref processor is used to record any discovered 909 // references during the full GC. 910 // 911 // At the end of a full GC we: 912 // * Enqueue any reference objects discovered by the STW ref processor 913 // that have non-live referents. This has the side-effect of 914 // making the STW ref processor inactive by disabling discovery. 915 // * Verify that the CM ref processor is still inactive 916 // and no references have been placed on it's discovered 917 // lists (also checked as a precondition during initial marking). 918 919 // The (stw) reference processor... 920 ReferenceProcessor* _ref_processor_stw; 921 922 STWGCTimer* _gc_timer_stw; 923 924 G1NewTracer* _gc_tracer_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 void set_refine_cte_cl_concurrency(bool concurrent); 957 958 RefToScanQueue *task_queue(uint i) const; 959 960 uint num_task_queues() const; 961 962 // A set of cards where updates happened during the GC 963 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 964 965 // Create a G1CollectedHeap with the specified policy. 966 // Must call the initialize method afterwards. 967 // May not return if something goes wrong. 968 G1CollectedHeap(G1CollectorPolicy* policy); 969 970 private: 971 jint initialize_concurrent_refinement(); 972 public: 973 // Initialize the G1CollectedHeap to have the initial and 974 // maximum sizes and remembered and barrier sets 975 // specified by the policy object. 976 jint initialize(); 977 978 virtual void stop(); 979 980 // Return the (conservative) maximum heap alignment for any G1 heap 981 static size_t conservative_max_heap_alignment(); 982 983 // Does operations required after initialization has been done. 984 void post_initialize(); 985 986 // Initialize weak reference processing. 987 void ref_processing_init(); 988 989 virtual Name kind() const { 990 return CollectedHeap::G1CollectedHeap; 991 } 992 993 virtual const char* name() const { 994 return "G1"; 995 } 996 997 const G1CollectorState* collector_state() const { return &_collector_state; } 998 G1CollectorState* collector_state() { return &_collector_state; } 999 1000 // The current policy object for the collector. 1001 G1Policy* g1_policy() const { return _g1_policy; } 1002 1003 const G1CollectionSet* collection_set() const { return &_collection_set; } 1004 G1CollectionSet* collection_set() { return &_collection_set; } 1005 1006 virtual CollectorPolicy* collector_policy() const; 1007 1008 // Adaptive size policy. No such thing for g1. 1009 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1010 1011 // The rem set and barrier set. 1012 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1013 1014 // Try to minimize the remembered set. 1015 void scrub_rem_set(); 1016 1017 uint get_gc_time_stamp() { 1018 return _gc_time_stamp; 1019 } 1020 1021 inline void reset_gc_time_stamp(); 1022 1023 void check_gc_time_stamps() PRODUCT_RETURN; 1024 1025 inline void increment_gc_time_stamp(); 1026 1027 // Reset the given region's GC timestamp. If it's starts humongous, 1028 // also reset the GC timestamp of its corresponding 1029 // continues humongous regions too. 1030 void reset_gc_time_stamps(HeapRegion* hr); 1031 1032 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 1033 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i); 1034 1035 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. 1036 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i); 1037 1038 // The shared block offset table array. 1039 G1BlockOffsetTable* bot() const { return _bot; } 1040 1041 // Reference Processing accessors 1042 1043 // The STW reference processor.... 1044 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1045 1046 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1047 1048 // The Concurrent Marking reference processor... 1049 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1050 1051 virtual size_t capacity() const; 1052 virtual size_t used() const; 1053 // This should be called when we're not holding the heap lock. The 1054 // result might be a bit inaccurate. 1055 size_t used_unlocked() const; 1056 size_t recalculate_used() const; 1057 1058 // These virtual functions do the actual allocation. 1059 // Some heaps may offer a contiguous region for shared non-blocking 1060 // allocation, via inlined code (by exporting the address of the top and 1061 // end fields defining the extent of the contiguous allocation region.) 1062 // But G1CollectedHeap doesn't yet support this. 1063 1064 virtual bool is_maximal_no_gc() const { 1065 return _hrm.available() == 0; 1066 } 1067 1068 // The current number of regions in the heap. 1069 uint num_regions() const { return _hrm.length(); } 1070 1071 // The max number of regions in the heap. 1072 uint max_regions() const { return _hrm.max_length(); } 1073 1074 // The number of regions that are completely free. 1075 uint num_free_regions() const { return _hrm.num_free_regions(); } 1076 1077 MemoryUsage get_auxiliary_data_memory_usage() const { 1078 return _hrm.get_auxiliary_data_memory_usage(); 1079 } 1080 1081 // The number of regions that are not completely free. 1082 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1083 1084 #ifdef ASSERT 1085 bool is_on_master_free_list(HeapRegion* hr) { 1086 return _hrm.is_free(hr); 1087 } 1088 #endif // ASSERT 1089 1090 // Wrapper for the region list operations that can be called from 1091 // methods outside this class. 1092 1093 void secondary_free_list_add(FreeRegionList* list) { 1094 _secondary_free_list.add_ordered(list); 1095 } 1096 1097 void append_secondary_free_list() { 1098 _hrm.insert_list_into_free_list(&_secondary_free_list); 1099 } 1100 1101 void append_secondary_free_list_if_not_empty_with_lock() { 1102 // If the secondary free list looks empty there's no reason to 1103 // take the lock and then try to append it. 1104 if (!_secondary_free_list.is_empty()) { 1105 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1106 append_secondary_free_list(); 1107 } 1108 } 1109 1110 inline void old_set_add(HeapRegion* hr); 1111 inline void old_set_remove(HeapRegion* hr); 1112 1113 size_t non_young_capacity_bytes() { 1114 return (_old_set.length() + _humongous_set.length()) * HeapRegion::GrainBytes; 1115 } 1116 1117 void set_free_regions_coming(); 1118 void reset_free_regions_coming(); 1119 bool free_regions_coming() { return _free_regions_coming; } 1120 void wait_while_free_regions_coming(); 1121 1122 // Determine whether the given region is one that we are using as an 1123 // old GC alloc region. 1124 bool is_old_gc_alloc_region(HeapRegion* hr); 1125 1126 // Perform a collection of the heap; intended for use in implementing 1127 // "System.gc". This probably implies as full a collection as the 1128 // "CollectedHeap" supports. 1129 virtual void collect(GCCause::Cause cause); 1130 1131 virtual bool copy_allocation_context_stats(const jint* contexts, 1132 jlong* totals, 1133 jbyte* accuracy, 1134 jint len); 1135 1136 // True iff an evacuation has failed in the most-recent collection. 1137 bool evacuation_failed() { return _evacuation_failed; } 1138 1139 void remove_from_old_sets(const uint old_regions_removed, const uint humongous_regions_removed); 1140 void prepend_to_freelist(FreeRegionList* list); 1141 void decrement_summary_bytes(size_t bytes); 1142 1143 virtual bool is_in(const void* p) const; 1144 #ifdef ASSERT 1145 // Returns whether p is in one of the available areas of the heap. Slow but 1146 // extensive version. 1147 bool is_in_exact(const void* p) const; 1148 #endif 1149 1150 // Return "TRUE" iff the given object address is within the collection 1151 // set. Assumes that the reference points into the heap. 1152 inline bool is_in_cset(const HeapRegion *hr); 1153 inline bool is_in_cset(oop obj); 1154 inline bool is_in_cset(HeapWord* addr); 1155 1156 inline bool is_in_cset_or_humongous(const oop obj); 1157 1158 private: 1159 // This array is used for a quick test on whether a reference points into 1160 // the collection set or not. Each of the array's elements denotes whether the 1161 // corresponding region is in the collection set or not. 1162 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1163 1164 public: 1165 1166 inline InCSetState in_cset_state(const oop obj); 1167 1168 // Return "TRUE" iff the given object address is in the reserved 1169 // region of g1. 1170 bool is_in_g1_reserved(const void* p) const { 1171 return _hrm.reserved().contains(p); 1172 } 1173 1174 // Returns a MemRegion that corresponds to the space that has been 1175 // reserved for the heap 1176 MemRegion g1_reserved() const { 1177 return _hrm.reserved(); 1178 } 1179 1180 virtual bool is_in_closed_subset(const void* p) const; 1181 1182 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1183 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set()); 1184 } 1185 1186 // Iteration functions. 1187 1188 // Iterate over all objects, calling "cl.do_object" on each. 1189 virtual void object_iterate(ObjectClosure* cl); 1190 1191 virtual void safe_object_iterate(ObjectClosure* cl) { 1192 object_iterate(cl); 1193 } 1194 1195 // Iterate over heap regions, in address order, terminating the 1196 // iteration early if the "doHeapRegion" method returns "true". 1197 void heap_region_iterate(HeapRegionClosure* blk) const; 1198 1199 // Return the region with the given index. It assumes the index is valid. 1200 inline HeapRegion* region_at(uint index) const; 1201 1202 // Return the next region (by index) that is part of the same 1203 // humongous object that hr is part of. 1204 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1205 1206 // Calculate the region index of the given address. Given address must be 1207 // within the heap. 1208 inline uint addr_to_region(HeapWord* addr) const; 1209 1210 inline HeapWord* bottom_addr_for_region(uint index) const; 1211 1212 // Iterate over the heap regions in parallel. Assumes that this will be called 1213 // in parallel by a number of worker threads with distinct worker ids 1214 // in the range passed to the HeapRegionClaimer. Applies "blk->doHeapRegion" 1215 // to each of the regions, by attempting to claim the region using the 1216 // HeapRegionClaimer and, if successful, applying the closure to the claimed 1217 // region. 1218 void heap_region_par_iterate(HeapRegionClosure* cl, 1219 uint worker_id, 1220 HeapRegionClaimerBase* hrclaimer) const; 1221 1222 // Iterate over the regions (if any) in the current collection set. 1223 void collection_set_iterate(HeapRegionClosure* blk); 1224 1225 // Iterate over the regions (if any) in the current collection set. Starts the 1226 // iteration over the entire collection set so that the start regions of a given 1227 // worker id over the set active_workers are evenly spread across the set of 1228 // collection set regions. 1229 void collection_set_iterate_from(HeapRegionClosure *blk, uint worker_id); 1230 1231 // Returns the HeapRegion that contains addr. addr must not be NULL. 1232 template <class T> 1233 inline HeapRegion* heap_region_containing(const T addr) const; 1234 1235 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1236 // each address in the (reserved) heap is a member of exactly 1237 // one block. The defining characteristic of a block is that it is 1238 // possible to find its size, and thus to progress forward to the next 1239 // block. (Blocks may be of different sizes.) Thus, blocks may 1240 // represent Java objects, or they might be free blocks in a 1241 // free-list-based heap (or subheap), as long as the two kinds are 1242 // distinguishable and the size of each is determinable. 1243 1244 // Returns the address of the start of the "block" that contains the 1245 // address "addr". We say "blocks" instead of "object" since some heaps 1246 // may not pack objects densely; a chunk may either be an object or a 1247 // non-object. 1248 virtual HeapWord* block_start(const void* addr) const; 1249 1250 // Requires "addr" to be the start of a chunk, and returns its size. 1251 // "addr + size" is required to be the start of a new chunk, or the end 1252 // of the active area of the heap. 1253 virtual size_t block_size(const HeapWord* addr) const; 1254 1255 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1256 // the block is an object. 1257 virtual bool block_is_obj(const HeapWord* addr) const; 1258 1259 // Section on thread-local allocation buffers (TLABs) 1260 // See CollectedHeap for semantics. 1261 1262 bool supports_tlab_allocation() const; 1263 size_t tlab_capacity(Thread* ignored) const; 1264 size_t tlab_used(Thread* ignored) const; 1265 size_t max_tlab_size() const; 1266 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1267 1268 // Can a compiler initialize a new object without store barriers? 1269 // This permission only extends from the creation of a new object 1270 // via a TLAB up to the first subsequent safepoint. If such permission 1271 // is granted for this heap type, the compiler promises to call 1272 // defer_store_barrier() below on any slow path allocation of 1273 // a new object for which such initializing store barriers will 1274 // have been elided. G1, like CMS, allows this, but should be 1275 // ready to provide a compensating write barrier as necessary 1276 // if that storage came out of a non-young region. The efficiency 1277 // of this implementation depends crucially on being able to 1278 // answer very efficiently in constant time whether a piece of 1279 // storage in the heap comes from a young region or not. 1280 // See ReduceInitialCardMarks. 1281 virtual bool can_elide_tlab_store_barriers() const { 1282 return true; 1283 } 1284 1285 virtual bool card_mark_must_follow_store() const { 1286 return true; 1287 } 1288 1289 inline bool is_in_young(const oop obj); 1290 1291 virtual bool is_scavengable(const void* addr); 1292 1293 // We don't need barriers for initializing stores to objects 1294 // in the young gen: for the SATB pre-barrier, there is no 1295 // pre-value that needs to be remembered; for the remembered-set 1296 // update logging post-barrier, we don't maintain remembered set 1297 // information for young gen objects. 1298 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1299 1300 // Returns "true" iff the given word_size is "very large". 1301 static bool is_humongous(size_t word_size) { 1302 // Note this has to be strictly greater-than as the TLABs 1303 // are capped at the humongous threshold and we want to 1304 // ensure that we don't try to allocate a TLAB as 1305 // humongous and that we don't allocate a humongous 1306 // object in a TLAB. 1307 return word_size > _humongous_object_threshold_in_words; 1308 } 1309 1310 // Returns the humongous threshold for a specific region size 1311 static size_t humongous_threshold_for(size_t region_size) { 1312 return (region_size / 2); 1313 } 1314 1315 // Returns the number of regions the humongous object of the given word size 1316 // requires. 1317 static size_t humongous_obj_size_in_regions(size_t word_size); 1318 1319 // Print the maximum heap capacity. 1320 virtual size_t max_capacity() const; 1321 1322 virtual jlong millis_since_last_gc(); 1323 1324 1325 // Convenience function to be used in situations where the heap type can be 1326 // asserted to be this type. 1327 static G1CollectedHeap* heap(); 1328 1329 void set_region_short_lived_locked(HeapRegion* hr); 1330 // add appropriate methods for any other surv rate groups 1331 1332 const G1SurvivorRegions* survivor() const { return &_survivor; } 1333 1334 uint survivor_regions_count() const { 1335 return _survivor.length(); 1336 } 1337 1338 uint eden_regions_count() const { 1339 return _eden.length(); 1340 } 1341 1342 uint young_regions_count() const { 1343 return _eden.length() + _survivor.length(); 1344 } 1345 1346 uint old_regions_count() const { return _old_set.length(); } 1347 1348 uint humongous_regions_count() const { return _humongous_set.length(); } 1349 1350 #ifdef ASSERT 1351 bool check_young_list_empty(); 1352 #endif 1353 1354 // *** Stuff related to concurrent marking. It's not clear to me that so 1355 // many of these need to be public. 1356 1357 // The functions below are helper functions that a subclass of 1358 // "CollectedHeap" can use in the implementation of its virtual 1359 // functions. 1360 // This performs a concurrent marking of the live objects in a 1361 // bitmap off to the side. 1362 void doConcurrentMark(); 1363 1364 bool isMarkedNext(oop obj) const; 1365 1366 // Determine if an object is dead, given the object and also 1367 // the region to which the object belongs. An object is dead 1368 // iff a) it was not allocated since the last mark, b) it 1369 // is not marked, and c) it is not in an archive region. 1370 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1371 return 1372 hr->is_obj_dead(obj, _cm->prevMarkBitMap()) && 1373 !hr->is_archive(); 1374 } 1375 1376 // This function returns true when an object has been 1377 // around since the previous marking and hasn't yet 1378 // been marked during this marking, and is not in an archive region. 1379 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1380 return 1381 !hr->obj_allocated_since_next_marking(obj) && 1382 !isMarkedNext(obj) && 1383 !hr->is_archive(); 1384 } 1385 1386 // Determine if an object is dead, given only the object itself. 1387 // This will find the region to which the object belongs and 1388 // then call the region version of the same function. 1389 1390 // Added if it is NULL it isn't dead. 1391 1392 inline bool is_obj_dead(const oop obj) const; 1393 1394 inline bool is_obj_ill(const oop obj) const; 1395 1396 G1ConcurrentMark* concurrent_mark() const { return _cm; } 1397 1398 // Refinement 1399 1400 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1401 1402 // Optimized nmethod scanning support routines 1403 1404 // Register the given nmethod with the G1 heap. 1405 virtual void register_nmethod(nmethod* nm); 1406 1407 // Unregister the given nmethod from the G1 heap. 1408 virtual void unregister_nmethod(nmethod* nm); 1409 1410 // Free up superfluous code root memory. 1411 void purge_code_root_memory(); 1412 1413 // Rebuild the strong code root lists for each region 1414 // after a full GC. 1415 void rebuild_strong_code_roots(); 1416 1417 // Partial cleaning used when class unloading is disabled. 1418 // Let the caller choose what structures to clean out: 1419 // - StringTable 1420 // - SymbolTable 1421 // - StringDeduplication structures 1422 void partial_cleaning(BoolObjectClosure* is_alive, bool unlink_strings, bool unlink_symbols, bool unlink_string_dedup); 1423 1424 // Complete cleaning used when class unloading is enabled. 1425 // Cleans out all structures handled by partial_cleaning and also the CodeCache. 1426 void complete_cleaning(BoolObjectClosure* is_alive, bool class_unloading_occurred); 1427 1428 // Redirty logged cards in the refinement queue. 1429 void redirty_logged_cards(); 1430 // Verification 1431 1432 // Perform any cleanup actions necessary before allowing a verification. 1433 virtual void prepare_for_verify(); 1434 1435 // Perform verification. 1436 1437 // vo == UsePrevMarking -> use "prev" marking information, 1438 // vo == UseNextMarking -> use "next" marking information 1439 // vo == UseMarkWord -> use the mark word in the object header 1440 // 1441 // NOTE: Only the "prev" marking information is guaranteed to be 1442 // consistent most of the time, so most calls to this should use 1443 // vo == UsePrevMarking. 1444 // Currently, there is only one case where this is called with 1445 // vo == UseNextMarking, which is to verify the "next" marking 1446 // information at the end of remark. 1447 // Currently there is only one place where this is called with 1448 // vo == UseMarkWord, which is to verify the marking during a 1449 // full GC. 1450 void verify(VerifyOption vo); 1451 1452 // WhiteBox testing support. 1453 virtual bool supports_concurrent_phase_control() const; 1454 virtual const char* const* concurrent_phases() const; 1455 virtual bool request_concurrent_phase(const char* phase); 1456 1457 // The methods below are here for convenience and dispatch the 1458 // appropriate method depending on value of the given VerifyOption 1459 // parameter. The values for that parameter, and their meanings, 1460 // are the same as those above. 1461 1462 bool is_obj_dead_cond(const oop obj, 1463 const HeapRegion* hr, 1464 const VerifyOption vo) const; 1465 1466 bool is_obj_dead_cond(const oop obj, 1467 const VerifyOption vo) const; 1468 1469 G1HeapSummary create_g1_heap_summary(); 1470 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1471 1472 // Printing 1473 private: 1474 void print_heap_regions() const; 1475 void print_regions_on(outputStream* st) const; 1476 1477 public: 1478 virtual void print_on(outputStream* st) const; 1479 virtual void print_extended_on(outputStream* st) const; 1480 virtual void print_on_error(outputStream* st) const; 1481 1482 virtual void print_gc_threads_on(outputStream* st) const; 1483 virtual void gc_threads_do(ThreadClosure* tc) const; 1484 1485 // Override 1486 void print_tracing_info() const; 1487 1488 // The following two methods are helpful for debugging RSet issues. 1489 void print_cset_rsets() PRODUCT_RETURN; 1490 void print_all_rsets() PRODUCT_RETURN; 1491 1492 public: 1493 size_t pending_card_num(); 1494 1495 protected: 1496 size_t _max_heap_capacity; 1497 }; 1498 1499 class G1ParEvacuateFollowersClosure : public VoidClosure { 1500 private: 1501 double _start_term; 1502 double _term_time; 1503 size_t _term_attempts; 1504 1505 void start_term_time() { _term_attempts++; _start_term = os::elapsedTime(); } 1506 void end_term_time() { _term_time += os::elapsedTime() - _start_term; } 1507 protected: 1508 G1CollectedHeap* _g1h; 1509 G1ParScanThreadState* _par_scan_state; 1510 RefToScanQueueSet* _queues; 1511 ParallelTaskTerminator* _terminator; 1512 1513 G1ParScanThreadState* par_scan_state() { return _par_scan_state; } 1514 RefToScanQueueSet* queues() { return _queues; } 1515 ParallelTaskTerminator* terminator() { return _terminator; } 1516 1517 public: 1518 G1ParEvacuateFollowersClosure(G1CollectedHeap* g1h, 1519 G1ParScanThreadState* par_scan_state, 1520 RefToScanQueueSet* queues, 1521 ParallelTaskTerminator* terminator) 1522 : _g1h(g1h), _par_scan_state(par_scan_state), 1523 _queues(queues), _terminator(terminator), 1524 _start_term(0.0), _term_time(0.0), _term_attempts(0) {} 1525 1526 void do_void(); 1527 1528 double term_time() const { return _term_time; } 1529 size_t term_attempts() const { return _term_attempts; } 1530 1531 private: 1532 inline bool offer_termination(); 1533 }; 1534 1535 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP