1 /* 2 * Copyright (c) 2001, 2015, 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/concurrentMark.hpp" 29 #include "gc/g1/evacuationInfo.hpp" 30 #include "gc/g1/g1AllocationContext.hpp" 31 #include "gc/g1/g1BiasedArray.hpp" 32 #include "gc/g1/g1CollectorState.hpp" 33 #include "gc/g1/g1HRPrinter.hpp" 34 #include "gc/g1/g1InCSetState.hpp" 35 #include "gc/g1/g1MonitoringSupport.hpp" 36 #include "gc/g1/g1EvacStats.hpp" 37 #include "gc/g1/g1SATBCardTableModRefBS.hpp" 38 #include "gc/g1/g1YCTypes.hpp" 39 #include "gc/g1/hSpaceCounters.hpp" 40 #include "gc/g1/heapRegionManager.hpp" 41 #include "gc/g1/heapRegionSet.hpp" 42 #include "gc/shared/barrierSet.hpp" 43 #include "gc/shared/collectedHeap.hpp" 44 #include "gc/shared/plab.hpp" 45 #include "memory/memRegion.hpp" 46 #include "utilities/stack.hpp" 47 48 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 49 // It uses the "Garbage First" heap organization and algorithm, which 50 // may combine concurrent marking with parallel, incremental compaction of 51 // heap subsets that will yield large amounts of garbage. 52 53 // Forward declarations 54 class HeapRegion; 55 class HRRSCleanupTask; 56 class GenerationSpec; 57 class OopsInHeapRegionClosure; 58 class G1ParScanThreadState; 59 class G1ParScanThreadStateSet; 60 class G1KlassScanClosure; 61 class G1ParScanThreadState; 62 class ObjectClosure; 63 class SpaceClosure; 64 class CompactibleSpaceClosure; 65 class Space; 66 class G1CollectorPolicy; 67 class GenRemSet; 68 class G1RemSet; 69 class HeapRegionRemSetIterator; 70 class ConcurrentMark; 71 class ConcurrentMarkThread; 72 class ConcurrentG1Refine; 73 class ConcurrentGCTimer; 74 class GenerationCounters; 75 class STWGCTimer; 76 class G1NewTracer; 77 class G1OldTracer; 78 class EvacuationFailedInfo; 79 class nmethod; 80 class Ticks; 81 class WorkGang; 82 class G1Allocator; 83 class G1ArchiveAllocator; 84 85 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 86 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 87 88 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 89 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 90 91 class YoungList : public CHeapObj<mtGC> { 92 private: 93 G1CollectedHeap* _g1h; 94 95 HeapRegion* _head; 96 97 HeapRegion* _survivor_head; 98 HeapRegion* _survivor_tail; 99 100 HeapRegion* _curr; 101 102 uint _length; 103 uint _survivor_length; 104 105 size_t _last_sampled_rs_lengths; 106 size_t _sampled_rs_lengths; 107 108 void empty_list(HeapRegion* list); 109 110 public: 111 YoungList(G1CollectedHeap* g1h); 112 113 void push_region(HeapRegion* hr); 114 void add_survivor_region(HeapRegion* hr); 115 116 void empty_list(); 117 bool is_empty() { return _length == 0; } 118 uint length() { return _length; } 119 uint eden_length() { return length() - survivor_length(); } 120 uint survivor_length() { return _survivor_length; } 121 122 // Currently we do not keep track of the used byte sum for the 123 // young list and the survivors and it'd be quite a lot of work to 124 // do so. When we'll eventually replace the young list with 125 // instances of HeapRegionLinkedList we'll get that for free. So, 126 // we'll report the more accurate information then. 127 size_t eden_used_bytes() { 128 assert(length() >= survivor_length(), "invariant"); 129 return (size_t) eden_length() * HeapRegion::GrainBytes; 130 } 131 size_t survivor_used_bytes() { 132 return (size_t) survivor_length() * HeapRegion::GrainBytes; 133 } 134 135 void rs_length_sampling_init(); 136 bool rs_length_sampling_more(); 137 void rs_length_sampling_next(); 138 139 void reset_sampled_info() { 140 _last_sampled_rs_lengths = 0; 141 } 142 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; } 143 144 // for development purposes 145 void reset_auxilary_lists(); 146 void clear() { _head = NULL; _length = 0; } 147 148 void clear_survivors() { 149 _survivor_head = NULL; 150 _survivor_tail = NULL; 151 _survivor_length = 0; 152 } 153 154 HeapRegion* first_region() { return _head; } 155 HeapRegion* first_survivor_region() { return _survivor_head; } 156 HeapRegion* last_survivor_region() { return _survivor_tail; } 157 158 // debugging 159 bool check_list_well_formed(); 160 bool check_list_empty(bool check_sample = true); 161 void print(); 162 }; 163 164 // The G1 STW is alive closure. 165 // An instance is embedded into the G1CH and used as the 166 // (optional) _is_alive_non_header closure in the STW 167 // reference processor. It is also extensively used during 168 // reference processing during STW evacuation pauses. 169 class G1STWIsAliveClosure: public BoolObjectClosure { 170 G1CollectedHeap* _g1; 171 public: 172 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 173 bool do_object_b(oop p); 174 }; 175 176 class RefineCardTableEntryClosure; 177 178 class G1RegionMappingChangedListener : public G1MappingChangedListener { 179 private: 180 void reset_from_card_cache(uint start_idx, size_t num_regions); 181 public: 182 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 183 }; 184 185 class G1CollectedHeap : public CollectedHeap { 186 friend class VM_CollectForMetadataAllocation; 187 friend class VM_G1CollectForAllocation; 188 friend class VM_G1CollectFull; 189 friend class VM_G1IncCollectionPause; 190 friend class VMStructs; 191 friend class MutatorAllocRegion; 192 friend class G1GCAllocRegion; 193 194 // Closures used in implementation. 195 friend class G1ParScanThreadState; 196 friend class G1ParScanThreadStateSet; 197 friend class G1ParTask; 198 friend class G1PLABAllocator; 199 friend class G1PrepareCompactClosure; 200 201 // Other related classes. 202 friend class HeapRegionClaimer; 203 204 // Testing classes. 205 friend class G1CheckCSetFastTableClosure; 206 207 private: 208 WorkGang* _workers; 209 210 static size_t _humongous_object_threshold_in_words; 211 212 // The secondary free list which contains regions that have been 213 // freed up during the cleanup process. This will be appended to 214 // the master free list when appropriate. 215 FreeRegionList _secondary_free_list; 216 217 // It keeps track of the old regions. 218 HeapRegionSet _old_set; 219 220 // It keeps track of the humongous regions. 221 HeapRegionSet _humongous_set; 222 223 void eagerly_reclaim_humongous_regions(); 224 225 // The number of regions we could create by expansion. 226 uint _expansion_regions; 227 228 // The block offset table for the G1 heap. 229 G1BlockOffsetSharedArray* _bot_shared; 230 231 // Tears down the region sets / lists so that they are empty and the 232 // regions on the heap do not belong to a region set / list. The 233 // only exception is the humongous set which we leave unaltered. If 234 // free_list_only is true, it will only tear down the master free 235 // list. It is called before a Full GC (free_list_only == false) or 236 // before heap shrinking (free_list_only == true). 237 void tear_down_region_sets(bool free_list_only); 238 239 // Rebuilds the region sets / lists so that they are repopulated to 240 // reflect the contents of the heap. The only exception is the 241 // humongous set which was not torn down in the first place. If 242 // free_list_only is true, it will only rebuild the master free 243 // list. It is called after a Full GC (free_list_only == false) or 244 // after heap shrinking (free_list_only == true). 245 void rebuild_region_sets(bool free_list_only); 246 247 // Callback for region mapping changed events. 248 G1RegionMappingChangedListener _listener; 249 250 // The sequence of all heap regions in the heap. 251 HeapRegionManager _hrm; 252 253 // Manages all allocations with regions except humongous object allocations. 254 G1Allocator* _allocator; 255 256 // Outside of GC pauses, the number of bytes used in all regions other 257 // than the current allocation region(s). 258 size_t _summary_bytes_used; 259 260 void increase_used(size_t bytes); 261 void decrease_used(size_t bytes); 262 263 void set_used(size_t bytes); 264 265 // Class that handles archive allocation ranges. 266 G1ArchiveAllocator* _archive_allocator; 267 268 // Statistics for each allocation context 269 AllocationContextStats _allocation_context_stats; 270 271 // GC allocation statistics policy for survivors. 272 G1EvacStats _survivor_evac_stats; 273 274 // GC allocation statistics policy for tenured objects. 275 G1EvacStats _old_evac_stats; 276 277 // It specifies whether we should attempt to expand the heap after a 278 // region allocation failure. If heap expansion fails we set this to 279 // false so that we don't re-attempt the heap expansion (it's likely 280 // that subsequent expansion attempts will also fail if one fails). 281 // Currently, it is only consulted during GC and it's reset at the 282 // start of each GC. 283 bool _expand_heap_after_alloc_failure; 284 285 // Helper for monitoring and management support. 286 G1MonitoringSupport* _g1mm; 287 288 // Records whether the region at the given index is (still) a 289 // candidate for eager reclaim. Only valid for humongous start 290 // regions; other regions have unspecified values. Humongous start 291 // regions are initialized at start of collection pause, with 292 // candidates removed from the set as they are found reachable from 293 // roots or the young generation. 294 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 295 protected: 296 bool default_value() const { return false; } 297 public: 298 void clear() { G1BiasedMappedArray<bool>::clear(); } 299 void set_candidate(uint region, bool value) { 300 set_by_index(region, value); 301 } 302 bool is_candidate(uint region) { 303 return get_by_index(region); 304 } 305 }; 306 307 HumongousReclaimCandidates _humongous_reclaim_candidates; 308 // Stores whether during humongous object registration we found candidate regions. 309 // If not, we can skip a few steps. 310 bool _has_humongous_reclaim_candidates; 311 312 volatile unsigned _gc_time_stamp; 313 314 G1HRPrinter _hr_printer; 315 316 // It decides whether an explicit GC should start a concurrent cycle 317 // instead of doing a STW GC. Currently, a concurrent cycle is 318 // explicitly started if: 319 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 320 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 321 // (c) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 322 // (d) cause == _g1_humongous_allocation 323 bool should_do_concurrent_full_gc(GCCause::Cause cause); 324 325 // indicates whether we are in young or mixed GC mode 326 G1CollectorState _collector_state; 327 328 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 329 // concurrent cycles) we have started. 330 volatile uint _old_marking_cycles_started; 331 332 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 333 // concurrent cycles) we have completed. 334 volatile uint _old_marking_cycles_completed; 335 336 bool _heap_summary_sent; 337 338 // This is a non-product method that is helpful for testing. It is 339 // called at the end of a GC and artificially expands the heap by 340 // allocating a number of dead regions. This way we can induce very 341 // frequent marking cycles and stress the cleanup / concurrent 342 // cleanup code more (as all the regions that will be allocated by 343 // this method will be found dead by the marking cycle). 344 void allocate_dummy_regions() PRODUCT_RETURN; 345 346 // Clear RSets after a compaction. It also resets the GC time stamps. 347 void clear_rsets_post_compaction(); 348 349 // If the HR printer is active, dump the state of the regions in the 350 // heap after a compaction. 351 void print_hrm_post_compaction(); 352 353 // Create a memory mapper for auxiliary data structures of the given size and 354 // translation factor. 355 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 356 size_t size, 357 size_t translation_factor); 358 359 double verify(bool guard, const char* msg); 360 void verify_before_gc(); 361 void verify_after_gc(); 362 363 void log_gc_header(); 364 void log_gc_footer(double pause_time_sec); 365 366 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 367 368 // These are macros so that, if the assert fires, we get the correct 369 // line number, file, etc. 370 371 #define heap_locking_asserts_params(_extra_message_) \ 372 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 373 (_extra_message_), \ 374 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 375 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 376 BOOL_TO_STR(Thread::current()->is_VM_thread()) 377 378 #define assert_heap_locked() \ 379 do { \ 380 assert(Heap_lock->owned_by_self(), \ 381 heap_locking_asserts_params("should be holding the Heap_lock")); \ 382 } while (0) 383 384 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 385 do { \ 386 assert(Heap_lock->owned_by_self() || \ 387 (SafepointSynchronize::is_at_safepoint() && \ 388 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 389 heap_locking_asserts_params("should be holding the Heap_lock or " \ 390 "should be at a safepoint")); \ 391 } while (0) 392 393 #define assert_heap_locked_and_not_at_safepoint() \ 394 do { \ 395 assert(Heap_lock->owned_by_self() && \ 396 !SafepointSynchronize::is_at_safepoint(), \ 397 heap_locking_asserts_params("should be holding the Heap_lock and " \ 398 "should not be at a safepoint")); \ 399 } while (0) 400 401 #define assert_heap_not_locked() \ 402 do { \ 403 assert(!Heap_lock->owned_by_self(), \ 404 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 405 } while (0) 406 407 #define assert_heap_not_locked_and_not_at_safepoint() \ 408 do { \ 409 assert(!Heap_lock->owned_by_self() && \ 410 !SafepointSynchronize::is_at_safepoint(), \ 411 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 412 "should not be at a safepoint")); \ 413 } while (0) 414 415 #define assert_at_safepoint(_should_be_vm_thread_) \ 416 do { \ 417 assert(SafepointSynchronize::is_at_safepoint() && \ 418 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 419 heap_locking_asserts_params("should be at a safepoint")); \ 420 } while (0) 421 422 #define assert_not_at_safepoint() \ 423 do { \ 424 assert(!SafepointSynchronize::is_at_safepoint(), \ 425 heap_locking_asserts_params("should not be at a safepoint")); \ 426 } while (0) 427 428 protected: 429 430 // The young region list. 431 YoungList* _young_list; 432 433 // The current policy object for the collector. 434 G1CollectorPolicy* _g1_policy; 435 436 // This is the second level of trying to allocate a new region. If 437 // new_region() didn't find a region on the free_list, this call will 438 // check whether there's anything available on the 439 // secondary_free_list and/or wait for more regions to appear on 440 // that list, if _free_regions_coming is set. 441 HeapRegion* new_region_try_secondary_free_list(bool is_old); 442 443 // Try to allocate a single non-humongous HeapRegion sufficient for 444 // an allocation of the given word_size. If do_expand is true, 445 // attempt to expand the heap if necessary to satisfy the allocation 446 // request. If the region is to be used as an old region or for a 447 // humongous object, set is_old to true. If not, to false. 448 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 449 450 // Initialize a contiguous set of free regions of length num_regions 451 // and starting at index first so that they appear as a single 452 // humongous region. 453 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 454 uint num_regions, 455 size_t word_size, 456 AllocationContext_t context); 457 458 // Attempt to allocate a humongous object of the given size. Return 459 // NULL if unsuccessful. 460 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 461 462 // The following two methods, allocate_new_tlab() and 463 // mem_allocate(), are the two main entry points from the runtime 464 // into the G1's allocation routines. They have the following 465 // assumptions: 466 // 467 // * They should both be called outside safepoints. 468 // 469 // * They should both be called without holding the Heap_lock. 470 // 471 // * All allocation requests for new TLABs should go to 472 // allocate_new_tlab(). 473 // 474 // * All non-TLAB allocation requests should go to mem_allocate(). 475 // 476 // * If either call cannot satisfy the allocation request using the 477 // current allocating region, they will try to get a new one. If 478 // this fails, they will attempt to do an evacuation pause and 479 // retry the allocation. 480 // 481 // * If all allocation attempts fail, even after trying to schedule 482 // an evacuation pause, allocate_new_tlab() will return NULL, 483 // whereas mem_allocate() will attempt a heap expansion and/or 484 // schedule a Full GC. 485 // 486 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 487 // should never be called with word_size being humongous. All 488 // humongous allocation requests should go to mem_allocate() which 489 // will satisfy them with a special path. 490 491 virtual HeapWord* allocate_new_tlab(size_t word_size); 492 493 virtual HeapWord* mem_allocate(size_t word_size, 494 bool* gc_overhead_limit_was_exceeded); 495 496 // The following three methods take a gc_count_before_ret 497 // parameter which is used to return the GC count if the method 498 // returns NULL. Given that we are required to read the GC count 499 // while holding the Heap_lock, and these paths will take the 500 // Heap_lock at some point, it's easier to get them to read the GC 501 // count while holding the Heap_lock before they return NULL instead 502 // of the caller (namely: mem_allocate()) having to also take the 503 // Heap_lock just to read the GC count. 504 505 // First-level mutator allocation attempt: try to allocate out of 506 // the mutator alloc region without taking the Heap_lock. This 507 // should only be used for non-humongous allocations. 508 inline HeapWord* attempt_allocation(size_t word_size, 509 uint* gc_count_before_ret, 510 uint* gclocker_retry_count_ret); 511 512 // Second-level mutator allocation attempt: take the Heap_lock and 513 // retry the allocation attempt, potentially scheduling a GC 514 // pause. This should only be used for non-humongous allocations. 515 HeapWord* attempt_allocation_slow(size_t word_size, 516 AllocationContext_t context, 517 uint* gc_count_before_ret, 518 uint* gclocker_retry_count_ret); 519 520 // Takes the Heap_lock and attempts a humongous allocation. It can 521 // potentially schedule a GC pause. 522 HeapWord* attempt_allocation_humongous(size_t word_size, 523 uint* gc_count_before_ret, 524 uint* gclocker_retry_count_ret); 525 526 // Allocation attempt that should be called during safepoints (e.g., 527 // at the end of a successful GC). expect_null_mutator_alloc_region 528 // specifies whether the mutator alloc region is expected to be NULL 529 // or not. 530 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 531 AllocationContext_t context, 532 bool expect_null_mutator_alloc_region); 533 534 // These methods are the "callbacks" from the G1AllocRegion class. 535 536 // For mutator alloc regions. 537 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 538 void retire_mutator_alloc_region(HeapRegion* alloc_region, 539 size_t allocated_bytes); 540 541 // For GC alloc regions. 542 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 543 InCSetState dest); 544 void retire_gc_alloc_region(HeapRegion* alloc_region, 545 size_t allocated_bytes, InCSetState dest); 546 547 // - if explicit_gc is true, the GC is for a System.gc() or a heap 548 // inspection request and should collect the entire heap 549 // - if clear_all_soft_refs is true, all soft references should be 550 // cleared during the GC 551 // - if explicit_gc is false, word_size describes the allocation that 552 // the GC should attempt (at least) to satisfy 553 // - it returns false if it is unable to do the collection due to the 554 // GC locker being active, true otherwise 555 bool do_collection(bool explicit_gc, 556 bool clear_all_soft_refs, 557 size_t word_size); 558 559 // Callback from VM_G1CollectFull operation. 560 // Perform a full collection. 561 virtual void do_full_collection(bool clear_all_soft_refs); 562 563 // Resize the heap if necessary after a full collection. If this is 564 // after a collect-for allocation, "word_size" is the allocation size, 565 // and will be considered part of the used portion of the heap. 566 void resize_if_necessary_after_full_collection(size_t word_size); 567 568 // Callback from VM_G1CollectForAllocation operation. 569 // This function does everything necessary/possible to satisfy a 570 // failed allocation request (including collection, expansion, etc.) 571 HeapWord* satisfy_failed_allocation(size_t word_size, 572 AllocationContext_t context, 573 bool* succeeded); 574 575 // Attempting to expand the heap sufficiently 576 // to support an allocation of the given "word_size". If 577 // successful, perform the allocation and return the address of the 578 // allocated block, or else "NULL". 579 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 580 581 // Process any reference objects discovered during 582 // an incremental evacuation pause. 583 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 584 585 // Enqueue any remaining discovered references 586 // after processing. 587 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states); 588 589 public: 590 WorkGang* workers() const { return _workers; } 591 592 G1Allocator* allocator() { 593 return _allocator; 594 } 595 596 G1MonitoringSupport* g1mm() { 597 assert(_g1mm != NULL, "should have been initialized"); 598 return _g1mm; 599 } 600 601 // Expand the garbage-first heap by at least the given size (in bytes!). 602 // Returns true if the heap was expanded by the requested amount; 603 // false otherwise. 604 // (Rounds up to a HeapRegion boundary.) 605 bool expand(size_t expand_bytes); 606 607 // Returns the PLAB statistics for a given destination. 608 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 609 610 // Determines PLAB size for a given destination. 611 inline size_t desired_plab_sz(InCSetState dest); 612 613 inline AllocationContextStats& allocation_context_stats(); 614 615 // Do anything common to GC's. 616 void gc_prologue(bool full); 617 void gc_epilogue(bool full); 618 619 // Modify the reclaim candidate set and test for presence. 620 // These are only valid for starts_humongous regions. 621 inline void set_humongous_reclaim_candidate(uint region, bool value); 622 inline bool is_humongous_reclaim_candidate(uint region); 623 624 // Remove from the reclaim candidate set. Also remove from the 625 // collection set so that later encounters avoid the slow path. 626 inline void set_humongous_is_live(oop obj); 627 628 // Register the given region to be part of the collection set. 629 inline void register_humongous_region_with_cset(uint index); 630 // Register regions with humongous objects (actually on the start region) in 631 // the in_cset_fast_test table. 632 void register_humongous_regions_with_cset(); 633 // We register a region with the fast "in collection set" test. We 634 // simply set to true the array slot corresponding to this region. 635 void register_young_region_with_cset(HeapRegion* r) { 636 _in_cset_fast_test.set_in_young(r->hrm_index()); 637 } 638 void register_old_region_with_cset(HeapRegion* r) { 639 _in_cset_fast_test.set_in_old(r->hrm_index()); 640 } 641 void clear_in_cset(const HeapRegion* hr) { 642 _in_cset_fast_test.clear(hr); 643 } 644 645 void clear_cset_fast_test() { 646 _in_cset_fast_test.clear(); 647 } 648 649 // This is called at the start of either a concurrent cycle or a Full 650 // GC to update the number of old marking cycles started. 651 void increment_old_marking_cycles_started(); 652 653 // This is called at the end of either a concurrent cycle or a Full 654 // GC to update the number of old marking cycles completed. Those two 655 // can happen in a nested fashion, i.e., we start a concurrent 656 // cycle, a Full GC happens half-way through it which ends first, 657 // and then the cycle notices that a Full GC happened and ends 658 // too. The concurrent parameter is a boolean to help us do a bit 659 // tighter consistency checking in the method. If concurrent is 660 // false, the caller is the inner caller in the nesting (i.e., the 661 // Full GC). If concurrent is true, the caller is the outer caller 662 // in this nesting (i.e., the concurrent cycle). Further nesting is 663 // not currently supported. The end of this call also notifies 664 // the FullGCCount_lock in case a Java thread is waiting for a full 665 // GC to happen (e.g., it called System.gc() with 666 // +ExplicitGCInvokesConcurrent). 667 void increment_old_marking_cycles_completed(bool concurrent); 668 669 uint old_marking_cycles_completed() { 670 return _old_marking_cycles_completed; 671 } 672 673 void register_concurrent_cycle_start(const Ticks& start_time); 674 void register_concurrent_cycle_end(); 675 void trace_heap_after_concurrent_cycle(); 676 677 G1HRPrinter* hr_printer() { return &_hr_printer; } 678 679 // Allocates a new heap region instance. 680 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 681 682 // Allocate the highest free region in the reserved heap. This will commit 683 // regions as necessary. 684 HeapRegion* alloc_highest_free_region(); 685 686 // Frees a non-humongous region by initializing its contents and 687 // adding it to the free list that's passed as a parameter (this is 688 // usually a local list which will be appended to the master free 689 // list later). The used bytes of freed regions are accumulated in 690 // pre_used. If par is true, the region's RSet will not be freed 691 // up. The assumption is that this will be done later. 692 // The locked parameter indicates if the caller has already taken 693 // care of proper synchronization. This may allow some optimizations. 694 void free_region(HeapRegion* hr, 695 FreeRegionList* free_list, 696 bool par, 697 bool locked = false); 698 699 // It dirties the cards that cover the block so that the post 700 // write barrier never queues anything when updating objects on this 701 // block. It is assumed (and in fact we assert) that the block 702 // belongs to a young region. 703 inline void dirty_young_block(HeapWord* start, size_t word_size); 704 705 // Frees a humongous region by collapsing it into individual regions 706 // and calling free_region() for each of them. The freed regions 707 // will be added to the free list that's passed as a parameter (this 708 // is usually a local list which will be appended to the master free 709 // list later). The used bytes of freed regions are accumulated in 710 // pre_used. If par is true, the region's RSet will not be freed 711 // up. The assumption is that this will be done later. 712 void free_humongous_region(HeapRegion* hr, 713 FreeRegionList* free_list, 714 bool par); 715 716 // Facility for allocating in 'archive' regions in high heap memory and 717 // recording the allocated ranges. These should all be called from the 718 // VM thread at safepoints, without the heap lock held. They can be used 719 // to create and archive a set of heap regions which can be mapped at the 720 // same fixed addresses in a subsequent JVM invocation. 721 void begin_archive_alloc_range(); 722 723 // Check if the requested size would be too large for an archive allocation. 724 bool is_archive_alloc_too_large(size_t word_size); 725 726 // Allocate memory of the requested size from the archive region. This will 727 // return NULL if the size is too large or if no memory is available. It 728 // does not trigger a garbage collection. 729 HeapWord* archive_mem_allocate(size_t word_size); 730 731 // Optionally aligns the end address and returns the allocated ranges in 732 // an array of MemRegions in order of ascending addresses. 733 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 734 size_t end_alignment_in_bytes = 0); 735 736 // Facility for allocating a fixed range within the heap and marking 737 // the containing regions as 'archive'. For use at JVM init time, when the 738 // caller may mmap archived heap data at the specified range(s). 739 // Verify that the MemRegions specified in the argument array are within the 740 // reserved heap. 741 bool check_archive_addresses(MemRegion* range, size_t count); 742 743 // Commit the appropriate G1 regions containing the specified MemRegions 744 // and mark them as 'archive' regions. The regions in the array must be 745 // non-overlapping and in order of ascending address. 746 bool alloc_archive_regions(MemRegion* range, size_t count); 747 748 // Insert any required filler objects in the G1 regions around the specified 749 // ranges to make the regions parseable. This must be called after 750 // alloc_archive_regions, and after class loading has occurred. 751 void fill_archive_regions(MemRegion* range, size_t count); 752 753 // For each of the specified MemRegions, uncommit the containing G1 regions 754 // which had been allocated by alloc_archive_regions. This should be called 755 // rather than fill_archive_regions at JVM init time if the archive file 756 // mapping failed, with the same non-overlapping and sorted MemRegion array. 757 void dealloc_archive_regions(MemRegion* range, size_t count); 758 759 protected: 760 761 // Shrink the garbage-first heap by at most the given size (in bytes!). 762 // (Rounds down to a HeapRegion boundary.) 763 virtual void shrink(size_t expand_bytes); 764 void shrink_helper(size_t expand_bytes); 765 766 #if TASKQUEUE_STATS 767 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 768 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 769 void reset_taskqueue_stats(); 770 #endif // TASKQUEUE_STATS 771 772 // Schedule the VM operation that will do an evacuation pause to 773 // satisfy an allocation request of word_size. *succeeded will 774 // return whether the VM operation was successful (it did do an 775 // evacuation pause) or not (another thread beat us to it or the GC 776 // locker was active). Given that we should not be holding the 777 // Heap_lock when we enter this method, we will pass the 778 // gc_count_before (i.e., total_collections()) as a parameter since 779 // it has to be read while holding the Heap_lock. Currently, both 780 // methods that call do_collection_pause() release the Heap_lock 781 // before the call, so it's easy to read gc_count_before just before. 782 HeapWord* do_collection_pause(size_t word_size, 783 uint gc_count_before, 784 bool* succeeded, 785 GCCause::Cause gc_cause); 786 787 void wait_for_root_region_scanning(); 788 789 // The guts of the incremental collection pause, executed by the vm 790 // thread. It returns false if it is unable to do the collection due 791 // to the GC locker being active, true otherwise 792 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 793 794 // Actually do the work of evacuating the collection set. 795 void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states); 796 797 // Print the header for the per-thread termination statistics. 798 static void print_termination_stats_hdr(outputStream* const st); 799 // Print actual per-thread termination statistics. 800 void print_termination_stats(outputStream* const st, 801 uint worker_id, 802 double elapsed_ms, 803 double strong_roots_ms, 804 double term_ms, 805 size_t term_attempts, 806 size_t alloc_buffer_waste, 807 size_t undo_waste) const; 808 // Update object copying statistics. 809 void record_obj_copy_mem_stats(); 810 811 // The g1 remembered set of the heap. 812 G1RemSet* _g1_rem_set; 813 814 // A set of cards that cover the objects for which the Rsets should be updated 815 // concurrently after the collection. 816 DirtyCardQueueSet _dirty_card_queue_set; 817 818 // The closure used to refine a single card. 819 RefineCardTableEntryClosure* _refine_cte_cl; 820 821 // A DirtyCardQueueSet that is used to hold cards that contain 822 // references into the current collection set. This is used to 823 // update the remembered sets of the regions in the collection 824 // set in the event of an evacuation failure. 825 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 826 827 // After a collection pause, make the regions in the CS into free 828 // regions. 829 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 830 831 // Abandon the current collection set without recording policy 832 // statistics or updating free lists. 833 void abandon_collection_set(HeapRegion* cs_head); 834 835 // The concurrent marker (and the thread it runs in.) 836 ConcurrentMark* _cm; 837 ConcurrentMarkThread* _cmThread; 838 839 // The concurrent refiner. 840 ConcurrentG1Refine* _cg1r; 841 842 // The parallel task queues 843 RefToScanQueueSet *_task_queues; 844 845 // True iff a evacuation has failed in the current collection. 846 bool _evacuation_failed; 847 848 EvacuationFailedInfo* _evacuation_failed_info_array; 849 850 // Failed evacuations cause some logical from-space objects to have 851 // forwarding pointers to themselves. Reset them. 852 void remove_self_forwarding_pointers(); 853 854 struct OopAndMarkOop { 855 private: 856 oop _o; 857 markOop _m; 858 public: 859 OopAndMarkOop(oop obj, markOop m) : _o(obj), _m(m) { 860 } 861 862 void set_mark() { 863 _o->set_mark(_m); 864 } 865 }; 866 867 typedef Stack<OopAndMarkOop,mtGC> OopAndMarkOopStack; 868 // Stores marks with the corresponding oop that we need to preserve during evacuation 869 // failure. 870 OopAndMarkOopStack* _preserved_objs; 871 872 // Preserve the mark of "obj", if necessary, in preparation for its mark 873 // word being overwritten with a self-forwarding-pointer. 874 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 875 876 #ifndef PRODUCT 877 // Support for forcing evacuation failures. Analogous to 878 // PromotionFailureALot for the other collectors. 879 880 // Records whether G1EvacuationFailureALot should be in effect 881 // for the current GC 882 bool _evacuation_failure_alot_for_current_gc; 883 884 // Used to record the GC number for interval checking when 885 // determining whether G1EvaucationFailureALot is in effect 886 // for the current GC. 887 size_t _evacuation_failure_alot_gc_number; 888 889 // Count of the number of evacuations between failures. 890 volatile size_t _evacuation_failure_alot_count; 891 892 // Set whether G1EvacuationFailureALot should be in effect 893 // for the current GC (based upon the type of GC and which 894 // command line flags are set); 895 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 896 bool during_initial_mark, 897 bool during_marking); 898 899 inline void set_evacuation_failure_alot_for_current_gc(); 900 901 // Return true if it's time to cause an evacuation failure. 902 inline bool evacuation_should_fail(); 903 904 // Reset the G1EvacuationFailureALot counters. Should be called at 905 // the end of an evacuation pause in which an evacuation failure occurred. 906 inline void reset_evacuation_should_fail(); 907 #endif // !PRODUCT 908 909 // ("Weak") Reference processing support. 910 // 911 // G1 has 2 instances of the reference processor class. One 912 // (_ref_processor_cm) handles reference object discovery 913 // and subsequent processing during concurrent marking cycles. 914 // 915 // The other (_ref_processor_stw) handles reference object 916 // discovery and processing during full GCs and incremental 917 // evacuation pauses. 918 // 919 // During an incremental pause, reference discovery will be 920 // temporarily disabled for _ref_processor_cm and will be 921 // enabled for _ref_processor_stw. At the end of the evacuation 922 // pause references discovered by _ref_processor_stw will be 923 // processed and discovery will be disabled. The previous 924 // setting for reference object discovery for _ref_processor_cm 925 // will be re-instated. 926 // 927 // At the start of marking: 928 // * Discovery by the CM ref processor is verified to be inactive 929 // and it's discovered lists are empty. 930 // * Discovery by the CM ref processor is then enabled. 931 // 932 // At the end of marking: 933 // * Any references on the CM ref processor's discovered 934 // lists are processed (possibly MT). 935 // 936 // At the start of full GC we: 937 // * Disable discovery by the CM ref processor and 938 // empty CM ref processor's discovered lists 939 // (without processing any entries). 940 // * Verify that the STW ref processor is inactive and it's 941 // discovered lists are empty. 942 // * Temporarily set STW ref processor discovery as single threaded. 943 // * Temporarily clear the STW ref processor's _is_alive_non_header 944 // field. 945 // * Finally enable discovery by the STW ref processor. 946 // 947 // The STW ref processor is used to record any discovered 948 // references during the full GC. 949 // 950 // At the end of a full GC we: 951 // * Enqueue any reference objects discovered by the STW ref processor 952 // that have non-live referents. This has the side-effect of 953 // making the STW ref processor inactive by disabling discovery. 954 // * Verify that the CM ref processor is still inactive 955 // and no references have been placed on it's discovered 956 // lists (also checked as a precondition during initial marking). 957 958 // The (stw) reference processor... 959 ReferenceProcessor* _ref_processor_stw; 960 961 STWGCTimer* _gc_timer_stw; 962 ConcurrentGCTimer* _gc_timer_cm; 963 964 G1OldTracer* _gc_tracer_cm; 965 G1NewTracer* _gc_tracer_stw; 966 967 // During reference object discovery, the _is_alive_non_header 968 // closure (if non-null) is applied to the referent object to 969 // determine whether the referent is live. If so then the 970 // reference object does not need to be 'discovered' and can 971 // be treated as a regular oop. This has the benefit of reducing 972 // the number of 'discovered' reference objects that need to 973 // be processed. 974 // 975 // Instance of the is_alive closure for embedding into the 976 // STW reference processor as the _is_alive_non_header field. 977 // Supplying a value for the _is_alive_non_header field is 978 // optional but doing so prevents unnecessary additions to 979 // the discovered lists during reference discovery. 980 G1STWIsAliveClosure _is_alive_closure_stw; 981 982 // The (concurrent marking) reference processor... 983 ReferenceProcessor* _ref_processor_cm; 984 985 // Instance of the concurrent mark is_alive closure for embedding 986 // into the Concurrent Marking reference processor as the 987 // _is_alive_non_header field. Supplying a value for the 988 // _is_alive_non_header field is optional but doing so prevents 989 // unnecessary additions to the discovered lists during reference 990 // discovery. 991 G1CMIsAliveClosure _is_alive_closure_cm; 992 993 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 994 HeapRegion** _worker_cset_start_region; 995 996 // Time stamp to validate the regions recorded in the cache 997 // used by G1CollectedHeap::start_cset_region_for_worker(). 998 // The heap region entry for a given worker is valid iff 999 // the associated time stamp value matches the current value 1000 // of G1CollectedHeap::_gc_time_stamp. 1001 uint* _worker_cset_start_region_time_stamp; 1002 1003 volatile bool _free_regions_coming; 1004 1005 public: 1006 1007 void set_refine_cte_cl_concurrency(bool concurrent); 1008 1009 RefToScanQueue *task_queue(uint i) const; 1010 1011 uint num_task_queues() const; 1012 1013 // A set of cards where updates happened during the GC 1014 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 1015 1016 // A DirtyCardQueueSet that is used to hold cards that contain 1017 // references into the current collection set. This is used to 1018 // update the remembered sets of the regions in the collection 1019 // set in the event of an evacuation failure. 1020 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 1021 { return _into_cset_dirty_card_queue_set; } 1022 1023 // Create a G1CollectedHeap with the specified policy. 1024 // Must call the initialize method afterwards. 1025 // May not return if something goes wrong. 1026 G1CollectedHeap(G1CollectorPolicy* policy); 1027 1028 // Initialize the G1CollectedHeap to have the initial and 1029 // maximum sizes and remembered and barrier sets 1030 // specified by the policy object. 1031 jint initialize(); 1032 1033 virtual void stop(); 1034 1035 // Return the (conservative) maximum heap alignment for any G1 heap 1036 static size_t conservative_max_heap_alignment(); 1037 1038 // Does operations required after initialization has been done. 1039 void post_initialize(); 1040 1041 // Initialize weak reference processing. 1042 void ref_processing_init(); 1043 1044 virtual Name kind() const { 1045 return CollectedHeap::G1CollectedHeap; 1046 } 1047 1048 G1CollectorState* collector_state() { return &_collector_state; } 1049 1050 // The current policy object for the collector. 1051 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1052 1053 virtual CollectorPolicy* collector_policy() const; 1054 1055 // Adaptive size policy. No such thing for g1. 1056 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1057 1058 // The rem set and barrier set. 1059 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1060 1061 unsigned get_gc_time_stamp() { 1062 return _gc_time_stamp; 1063 } 1064 1065 inline void reset_gc_time_stamp(); 1066 1067 void check_gc_time_stamps() PRODUCT_RETURN; 1068 1069 inline void increment_gc_time_stamp(); 1070 1071 // Reset the given region's GC timestamp. If it's starts humongous, 1072 // also reset the GC timestamp of its corresponding 1073 // continues humongous regions too. 1074 void reset_gc_time_stamps(HeapRegion* hr); 1075 1076 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1077 DirtyCardQueue* into_cset_dcq, 1078 bool concurrent, uint worker_i); 1079 1080 // The shared block offset table array. 1081 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1082 1083 // Reference Processing accessors 1084 1085 // The STW reference processor.... 1086 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1087 1088 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1089 1090 // The Concurrent Marking reference processor... 1091 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1092 1093 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } 1094 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } 1095 1096 virtual size_t capacity() const; 1097 virtual size_t used() const; 1098 // This should be called when we're not holding the heap lock. The 1099 // result might be a bit inaccurate. 1100 size_t used_unlocked() const; 1101 size_t recalculate_used() const; 1102 1103 // These virtual functions do the actual allocation. 1104 // Some heaps may offer a contiguous region for shared non-blocking 1105 // allocation, via inlined code (by exporting the address of the top and 1106 // end fields defining the extent of the contiguous allocation region.) 1107 // But G1CollectedHeap doesn't yet support this. 1108 1109 virtual bool is_maximal_no_gc() const { 1110 return _hrm.available() == 0; 1111 } 1112 1113 // The current number of regions in the heap. 1114 uint num_regions() const { return _hrm.length(); } 1115 1116 // The max number of regions in the heap. 1117 uint max_regions() const { return _hrm.max_length(); } 1118 1119 // The number of regions that are completely free. 1120 uint num_free_regions() const { return _hrm.num_free_regions(); } 1121 1122 MemoryUsage get_auxiliary_data_memory_usage() const { 1123 return _hrm.get_auxiliary_data_memory_usage(); 1124 } 1125 1126 // The number of regions that are not completely free. 1127 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1128 1129 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1130 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1131 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1132 void verify_dirty_young_regions() PRODUCT_RETURN; 1133 1134 #ifndef PRODUCT 1135 // Make sure that the given bitmap has no marked objects in the 1136 // range [from,limit). If it does, print an error message and return 1137 // false. Otherwise, just return true. bitmap_name should be "prev" 1138 // or "next". 1139 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 1140 HeapWord* from, HeapWord* limit); 1141 1142 // Verify that the prev / next bitmap range [tams,end) for the given 1143 // region has no marks. Return true if all is well, false if errors 1144 // are detected. 1145 bool verify_bitmaps(const char* caller, HeapRegion* hr); 1146 #endif // PRODUCT 1147 1148 // If G1VerifyBitmaps is set, verify that the marking bitmaps for 1149 // the given region do not have any spurious marks. If errors are 1150 // detected, print appropriate error messages and crash. 1151 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN; 1152 1153 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not 1154 // have any spurious marks. If errors are detected, print 1155 // appropriate error messages and crash. 1156 void check_bitmaps(const char* caller) PRODUCT_RETURN; 1157 1158 // Do sanity check on the contents of the in-cset fast test table. 1159 bool check_cset_fast_test() PRODUCT_RETURN_( return true; ); 1160 1161 // verify_region_sets() performs verification over the region 1162 // lists. It will be compiled in the product code to be used when 1163 // necessary (i.e., during heap verification). 1164 void verify_region_sets(); 1165 1166 // verify_region_sets_optional() is planted in the code for 1167 // list verification in non-product builds (and it can be enabled in 1168 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1). 1169 #if HEAP_REGION_SET_FORCE_VERIFY 1170 void verify_region_sets_optional() { 1171 verify_region_sets(); 1172 } 1173 #else // HEAP_REGION_SET_FORCE_VERIFY 1174 void verify_region_sets_optional() { } 1175 #endif // HEAP_REGION_SET_FORCE_VERIFY 1176 1177 #ifdef ASSERT 1178 bool is_on_master_free_list(HeapRegion* hr) { 1179 return _hrm.is_free(hr); 1180 } 1181 #endif // ASSERT 1182 1183 // Wrapper for the region list operations that can be called from 1184 // methods outside this class. 1185 1186 void secondary_free_list_add(FreeRegionList* list) { 1187 _secondary_free_list.add_ordered(list); 1188 } 1189 1190 void append_secondary_free_list() { 1191 _hrm.insert_list_into_free_list(&_secondary_free_list); 1192 } 1193 1194 void append_secondary_free_list_if_not_empty_with_lock() { 1195 // If the secondary free list looks empty there's no reason to 1196 // take the lock and then try to append it. 1197 if (!_secondary_free_list.is_empty()) { 1198 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1199 append_secondary_free_list(); 1200 } 1201 } 1202 1203 inline void old_set_add(HeapRegion* hr); 1204 inline void old_set_remove(HeapRegion* hr); 1205 1206 size_t non_young_capacity_bytes() { 1207 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1208 } 1209 1210 void set_free_regions_coming(); 1211 void reset_free_regions_coming(); 1212 bool free_regions_coming() { return _free_regions_coming; } 1213 void wait_while_free_regions_coming(); 1214 1215 // Determine whether the given region is one that we are using as an 1216 // old GC alloc region. 1217 bool is_old_gc_alloc_region(HeapRegion* hr); 1218 1219 // Perform a collection of the heap; intended for use in implementing 1220 // "System.gc". This probably implies as full a collection as the 1221 // "CollectedHeap" supports. 1222 virtual void collect(GCCause::Cause cause); 1223 1224 // The same as above but assume that the caller holds the Heap_lock. 1225 void collect_locked(GCCause::Cause cause); 1226 1227 virtual bool copy_allocation_context_stats(const jint* contexts, 1228 jlong* totals, 1229 jbyte* accuracy, 1230 jint len); 1231 1232 // True iff an evacuation has failed in the most-recent collection. 1233 bool evacuation_failed() { return _evacuation_failed; } 1234 1235 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed); 1236 void prepend_to_freelist(FreeRegionList* list); 1237 void decrement_summary_bytes(size_t bytes); 1238 1239 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1240 virtual bool is_in(const void* p) const; 1241 #ifdef ASSERT 1242 // Returns whether p is in one of the available areas of the heap. Slow but 1243 // extensive version. 1244 bool is_in_exact(const void* p) const; 1245 #endif 1246 1247 // Return "TRUE" iff the given object address is within the collection 1248 // set. Slow implementation. 1249 bool obj_in_cs(oop obj); 1250 1251 inline bool is_in_cset(const HeapRegion *hr); 1252 inline bool is_in_cset(oop obj); 1253 1254 inline bool is_in_cset_or_humongous(const oop obj); 1255 1256 private: 1257 // This array is used for a quick test on whether a reference points into 1258 // the collection set or not. Each of the array's elements denotes whether the 1259 // corresponding region is in the collection set or not. 1260 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1261 1262 public: 1263 1264 inline InCSetState in_cset_state(const oop obj); 1265 1266 // Return "TRUE" iff the given object address is in the reserved 1267 // region of g1. 1268 bool is_in_g1_reserved(const void* p) const { 1269 return _hrm.reserved().contains(p); 1270 } 1271 1272 // Returns a MemRegion that corresponds to the space that has been 1273 // reserved for the heap 1274 MemRegion g1_reserved() const { 1275 return _hrm.reserved(); 1276 } 1277 1278 virtual bool is_in_closed_subset(const void* p) const; 1279 1280 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1281 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set()); 1282 } 1283 1284 // This resets the card table to all zeros. It is used after 1285 // a collection pause which used the card table to claim cards. 1286 void cleanUpCardTable(); 1287 1288 // Iteration functions. 1289 1290 // Iterate over all objects, calling "cl.do_object" on each. 1291 virtual void object_iterate(ObjectClosure* cl); 1292 1293 virtual void safe_object_iterate(ObjectClosure* cl) { 1294 object_iterate(cl); 1295 } 1296 1297 // Iterate over heap regions, in address order, terminating the 1298 // iteration early if the "doHeapRegion" method returns "true". 1299 void heap_region_iterate(HeapRegionClosure* blk) const; 1300 1301 // Return the region with the given index. It assumes the index is valid. 1302 inline HeapRegion* region_at(uint index) const; 1303 1304 // Calculate the region index of the given address. Given address must be 1305 // within the heap. 1306 inline uint addr_to_region(HeapWord* addr) const; 1307 1308 inline HeapWord* bottom_addr_for_region(uint index) const; 1309 1310 // Iterate over the heap regions in parallel. Assumes that this will be called 1311 // in parallel by ParallelGCThreads worker threads with distinct worker ids 1312 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion" 1313 // to each of the regions, by attempting to claim the region using the 1314 // HeapRegionClaimer and, if successful, applying the closure to the claimed 1315 // region. The concurrent argument should be set to true if iteration is 1316 // performed concurrently, during which no assumptions are made for consistent 1317 // attributes of the heap regions (as they might be modified while iterating). 1318 void heap_region_par_iterate(HeapRegionClosure* cl, 1319 uint worker_id, 1320 HeapRegionClaimer* hrclaimer, 1321 bool concurrent = false) const; 1322 1323 // Clear the cached cset start regions and (more importantly) 1324 // the time stamps. Called when we reset the GC time stamp. 1325 void clear_cset_start_regions(); 1326 1327 // Given the id of a worker, obtain or calculate a suitable 1328 // starting region for iterating over the current collection set. 1329 HeapRegion* start_cset_region_for_worker(uint worker_i); 1330 1331 // Iterate over the regions (if any) in the current collection set. 1332 void collection_set_iterate(HeapRegionClosure* blk); 1333 1334 // As above but starting from region r 1335 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1336 1337 HeapRegion* next_compaction_region(const HeapRegion* from) const; 1338 1339 // Returns the HeapRegion that contains addr. addr must not be NULL. 1340 template <class T> 1341 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1342 1343 // Returns the HeapRegion that contains addr. addr must not be NULL. 1344 // If addr is within a humongous continues region, it returns its humongous start region. 1345 template <class T> 1346 inline HeapRegion* heap_region_containing(const T addr) const; 1347 1348 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1349 // each address in the (reserved) heap is a member of exactly 1350 // one block. The defining characteristic of a block is that it is 1351 // possible to find its size, and thus to progress forward to the next 1352 // block. (Blocks may be of different sizes.) Thus, blocks may 1353 // represent Java objects, or they might be free blocks in a 1354 // free-list-based heap (or subheap), as long as the two kinds are 1355 // distinguishable and the size of each is determinable. 1356 1357 // Returns the address of the start of the "block" that contains the 1358 // address "addr". We say "blocks" instead of "object" since some heaps 1359 // may not pack objects densely; a chunk may either be an object or a 1360 // non-object. 1361 virtual HeapWord* block_start(const void* addr) const; 1362 1363 // Requires "addr" to be the start of a chunk, and returns its size. 1364 // "addr + size" is required to be the start of a new chunk, or the end 1365 // of the active area of the heap. 1366 virtual size_t block_size(const HeapWord* addr) const; 1367 1368 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1369 // the block is an object. 1370 virtual bool block_is_obj(const HeapWord* addr) const; 1371 1372 // Section on thread-local allocation buffers (TLABs) 1373 // See CollectedHeap for semantics. 1374 1375 bool supports_tlab_allocation() const; 1376 size_t tlab_capacity(Thread* ignored) const; 1377 size_t tlab_used(Thread* ignored) const; 1378 size_t max_tlab_size() const; 1379 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1380 1381 // Can a compiler initialize a new object without store barriers? 1382 // This permission only extends from the creation of a new object 1383 // via a TLAB up to the first subsequent safepoint. If such permission 1384 // is granted for this heap type, the compiler promises to call 1385 // defer_store_barrier() below on any slow path allocation of 1386 // a new object for which such initializing store barriers will 1387 // have been elided. G1, like CMS, allows this, but should be 1388 // ready to provide a compensating write barrier as necessary 1389 // if that storage came out of a non-young region. The efficiency 1390 // of this implementation depends crucially on being able to 1391 // answer very efficiently in constant time whether a piece of 1392 // storage in the heap comes from a young region or not. 1393 // See ReduceInitialCardMarks. 1394 virtual bool can_elide_tlab_store_barriers() const { 1395 return true; 1396 } 1397 1398 virtual bool card_mark_must_follow_store() const { 1399 return true; 1400 } 1401 1402 inline bool is_in_young(const oop obj); 1403 1404 virtual bool is_scavengable(const void* addr); 1405 1406 // We don't need barriers for initializing stores to objects 1407 // in the young gen: for the SATB pre-barrier, there is no 1408 // pre-value that needs to be remembered; for the remembered-set 1409 // update logging post-barrier, we don't maintain remembered set 1410 // information for young gen objects. 1411 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1412 1413 // Returns "true" iff the given word_size is "very large". 1414 static bool is_humongous(size_t word_size) { 1415 // Note this has to be strictly greater-than as the TLABs 1416 // are capped at the humongous threshold and we want to 1417 // ensure that we don't try to allocate a TLAB as 1418 // humongous and that we don't allocate a humongous 1419 // object in a TLAB. 1420 return word_size > _humongous_object_threshold_in_words; 1421 } 1422 1423 // Returns the humongous threshold for a specific region size 1424 static size_t humongous_threshold_for(size_t region_size) { 1425 return (region_size / 2); 1426 } 1427 1428 // Update mod union table with the set of dirty cards. 1429 void updateModUnion(); 1430 1431 // Set the mod union bits corresponding to the given memRegion. Note 1432 // that this is always a safe operation, since it doesn't clear any 1433 // bits. 1434 void markModUnionRange(MemRegion mr); 1435 1436 // Print the maximum heap capacity. 1437 virtual size_t max_capacity() const; 1438 1439 virtual jlong millis_since_last_gc(); 1440 1441 1442 // Convenience function to be used in situations where the heap type can be 1443 // asserted to be this type. 1444 static G1CollectedHeap* heap(); 1445 1446 void set_region_short_lived_locked(HeapRegion* hr); 1447 // add appropriate methods for any other surv rate groups 1448 1449 YoungList* young_list() const { return _young_list; } 1450 1451 // debugging 1452 bool check_young_list_well_formed() { 1453 return _young_list->check_list_well_formed(); 1454 } 1455 1456 bool check_young_list_empty(bool check_heap, 1457 bool check_sample = true); 1458 1459 // *** Stuff related to concurrent marking. It's not clear to me that so 1460 // many of these need to be public. 1461 1462 // The functions below are helper functions that a subclass of 1463 // "CollectedHeap" can use in the implementation of its virtual 1464 // functions. 1465 // This performs a concurrent marking of the live objects in a 1466 // bitmap off to the side. 1467 void doConcurrentMark(); 1468 1469 bool isMarkedPrev(oop obj) const; 1470 bool isMarkedNext(oop obj) const; 1471 1472 // Determine if an object is dead, given the object and also 1473 // the region to which the object belongs. An object is dead 1474 // iff a) it was not allocated since the last mark, b) it 1475 // is not marked, and c) it is not in an archive region. 1476 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1477 return 1478 !hr->obj_allocated_since_prev_marking(obj) && 1479 !isMarkedPrev(obj) && 1480 !hr->is_archive(); 1481 } 1482 1483 // This function returns true when an object has been 1484 // around since the previous marking and hasn't yet 1485 // been marked during this marking, and is not in an archive region. 1486 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1487 return 1488 !hr->obj_allocated_since_next_marking(obj) && 1489 !isMarkedNext(obj) && 1490 !hr->is_archive(); 1491 } 1492 1493 // Determine if an object is dead, given only the object itself. 1494 // This will find the region to which the object belongs and 1495 // then call the region version of the same function. 1496 1497 // Added if it is NULL it isn't dead. 1498 1499 inline bool is_obj_dead(const oop obj) const; 1500 1501 inline bool is_obj_ill(const oop obj) const; 1502 1503 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1504 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1505 bool is_marked(oop obj, VerifyOption vo); 1506 const char* top_at_mark_start_str(VerifyOption vo); 1507 1508 ConcurrentMark* concurrent_mark() const { return _cm; } 1509 1510 // Refinement 1511 1512 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1513 1514 // The dirty cards region list is used to record a subset of regions 1515 // whose cards need clearing. The list if populated during the 1516 // remembered set scanning and drained during the card table 1517 // cleanup. Although the methods are reentrant, population/draining 1518 // phases must not overlap. For synchronization purposes the last 1519 // element on the list points to itself. 1520 HeapRegion* _dirty_cards_region_list; 1521 void push_dirty_cards_region(HeapRegion* hr); 1522 HeapRegion* pop_dirty_cards_region(); 1523 1524 // Optimized nmethod scanning support routines 1525 1526 // Register the given nmethod with the G1 heap. 1527 virtual void register_nmethod(nmethod* nm); 1528 1529 // Unregister the given nmethod from the G1 heap. 1530 virtual void unregister_nmethod(nmethod* nm); 1531 1532 // Free up superfluous code root memory. 1533 void purge_code_root_memory(); 1534 1535 // Rebuild the strong code root lists for each region 1536 // after a full GC. 1537 void rebuild_strong_code_roots(); 1538 1539 // Delete entries for dead interned string and clean up unreferenced symbols 1540 // in symbol table, possibly in parallel. 1541 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true); 1542 1543 // Parallel phase of unloading/cleaning after G1 concurrent mark. 1544 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred); 1545 1546 // Redirty logged cards in the refinement queue. 1547 void redirty_logged_cards(); 1548 // Verification 1549 1550 // Perform any cleanup actions necessary before allowing a verification. 1551 virtual void prepare_for_verify(); 1552 1553 // Perform verification. 1554 1555 // vo == UsePrevMarking -> use "prev" marking information, 1556 // vo == UseNextMarking -> use "next" marking information 1557 // vo == UseMarkWord -> use the mark word in the object header 1558 // 1559 // NOTE: Only the "prev" marking information is guaranteed to be 1560 // consistent most of the time, so most calls to this should use 1561 // vo == UsePrevMarking. 1562 // Currently, there is only one case where this is called with 1563 // vo == UseNextMarking, which is to verify the "next" marking 1564 // information at the end of remark. 1565 // Currently there is only one place where this is called with 1566 // vo == UseMarkWord, which is to verify the marking during a 1567 // full GC. 1568 void verify(bool silent, VerifyOption vo); 1569 1570 // Override; it uses the "prev" marking information 1571 virtual void verify(bool silent); 1572 1573 // The methods below are here for convenience and dispatch the 1574 // appropriate method depending on value of the given VerifyOption 1575 // parameter. The values for that parameter, and their meanings, 1576 // are the same as those above. 1577 1578 bool is_obj_dead_cond(const oop obj, 1579 const HeapRegion* hr, 1580 const VerifyOption vo) const; 1581 1582 bool is_obj_dead_cond(const oop obj, 1583 const VerifyOption vo) const; 1584 1585 G1HeapSummary create_g1_heap_summary(); 1586 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1587 1588 // Printing 1589 1590 virtual void print_on(outputStream* st) const; 1591 virtual void print_extended_on(outputStream* st) const; 1592 virtual void print_on_error(outputStream* st) const; 1593 1594 virtual void print_gc_threads_on(outputStream* st) const; 1595 virtual void gc_threads_do(ThreadClosure* tc) const; 1596 1597 // Override 1598 void print_tracing_info() const; 1599 1600 // The following two methods are helpful for debugging RSet issues. 1601 void print_cset_rsets() PRODUCT_RETURN; 1602 void print_all_rsets() PRODUCT_RETURN; 1603 1604 public: 1605 size_t pending_card_num(); 1606 1607 protected: 1608 size_t _max_heap_capacity; 1609 }; 1610 1611 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP