1 /* 2 * Copyright (c) 2001, 2011, 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_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP 26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP 27 28 #include "gc_implementation/g1/concurrentMark.hpp" 29 #include "gc_implementation/g1/g1AllocRegion.hpp" 30 #include "gc_implementation/g1/g1HRPrinter.hpp" 31 #include "gc_implementation/g1/g1RemSet.hpp" 32 #include "gc_implementation/g1/g1MonitoringSupport.hpp" 33 #include "gc_implementation/g1/heapRegionSeq.hpp" 34 #include "gc_implementation/g1/heapRegionSets.hpp" 35 #include "gc_implementation/shared/hSpaceCounters.hpp" 36 #include "gc_implementation/parNew/parGCAllocBuffer.hpp" 37 #include "memory/barrierSet.hpp" 38 #include "memory/memRegion.hpp" 39 #include "memory/sharedHeap.hpp" 40 41 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 42 // It uses the "Garbage First" heap organization and algorithm, which 43 // may combine concurrent marking with parallel, incremental compaction of 44 // heap subsets that will yield large amounts of garbage. 45 46 class HeapRegion; 47 class HRRSCleanupTask; 48 class PermanentGenerationSpec; 49 class GenerationSpec; 50 class OopsInHeapRegionClosure; 51 class G1ScanHeapEvacClosure; 52 class ObjectClosure; 53 class SpaceClosure; 54 class CompactibleSpaceClosure; 55 class Space; 56 class G1CollectorPolicy; 57 class GenRemSet; 58 class G1RemSet; 59 class HeapRegionRemSetIterator; 60 class ConcurrentMark; 61 class ConcurrentMarkThread; 62 class ConcurrentG1Refine; 63 class GenerationCounters; 64 65 typedef OverflowTaskQueue<StarTask> RefToScanQueue; 66 typedef GenericTaskQueueSet<RefToScanQueue> RefToScanQueueSet; 67 68 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 69 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 70 71 enum GCAllocPurpose { 72 GCAllocForTenured, 73 GCAllocForSurvived, 74 GCAllocPurposeCount 75 }; 76 77 class YoungList : public CHeapObj { 78 private: 79 G1CollectedHeap* _g1h; 80 81 HeapRegion* _head; 82 83 HeapRegion* _survivor_head; 84 HeapRegion* _survivor_tail; 85 86 HeapRegion* _curr; 87 88 size_t _length; 89 size_t _survivor_length; 90 91 size_t _last_sampled_rs_lengths; 92 size_t _sampled_rs_lengths; 93 94 void empty_list(HeapRegion* list); 95 96 public: 97 YoungList(G1CollectedHeap* g1h); 98 99 void push_region(HeapRegion* hr); 100 void add_survivor_region(HeapRegion* hr); 101 102 void empty_list(); 103 bool is_empty() { return _length == 0; } 104 size_t length() { return _length; } 105 size_t survivor_length() { return _survivor_length; } 106 107 // Currently we do not keep track of the used byte sum for the 108 // young list and the survivors and it'd be quite a lot of work to 109 // do so. When we'll eventually replace the young list with 110 // instances of HeapRegionLinkedList we'll get that for free. So, 111 // we'll report the more accurate information then. 112 size_t eden_used_bytes() { 113 assert(length() >= survivor_length(), "invariant"); 114 return (length() - survivor_length()) * HeapRegion::GrainBytes; 115 } 116 size_t survivor_used_bytes() { 117 return survivor_length() * HeapRegion::GrainBytes; 118 } 119 120 void rs_length_sampling_init(); 121 bool rs_length_sampling_more(); 122 void rs_length_sampling_next(); 123 124 void reset_sampled_info() { 125 _last_sampled_rs_lengths = 0; 126 } 127 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; } 128 129 // for development purposes 130 void reset_auxilary_lists(); 131 void clear() { _head = NULL; _length = 0; } 132 133 void clear_survivors() { 134 _survivor_head = NULL; 135 _survivor_tail = NULL; 136 _survivor_length = 0; 137 } 138 139 HeapRegion* first_region() { return _head; } 140 HeapRegion* first_survivor_region() { return _survivor_head; } 141 HeapRegion* last_survivor_region() { return _survivor_tail; } 142 143 // debugging 144 bool check_list_well_formed(); 145 bool check_list_empty(bool check_sample = true); 146 void print(); 147 }; 148 149 class MutatorAllocRegion : public G1AllocRegion { 150 protected: 151 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 152 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 153 public: 154 MutatorAllocRegion() 155 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { } 156 }; 157 158 // The G1 STW is alive closure. 159 // An instance is embedded into the G1CH and used as the 160 // _is_alive_non_header closure in the STW reference 161 // processor. It is also extensively used during refence 162 // processing during STW evacuation pauses. 163 class G1STWIsAliveClosure: public BoolObjectClosure { 164 G1CollectedHeap* _g1; 165 public: 166 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 167 void do_object(oop p) { assert(false, "Do not call."); } 168 bool do_object_b(oop p); 169 }; 170 171 class SurvivorGCAllocRegion : public G1AllocRegion { 172 protected: 173 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 174 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 175 public: 176 SurvivorGCAllocRegion() 177 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { } 178 }; 179 180 class OldGCAllocRegion : public G1AllocRegion { 181 protected: 182 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 183 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 184 public: 185 OldGCAllocRegion() 186 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { } 187 }; 188 189 class RefineCardTableEntryClosure; 190 191 class G1CollectedHeap : public SharedHeap { 192 friend class VM_G1CollectForAllocation; 193 friend class VM_GenCollectForPermanentAllocation; 194 friend class VM_G1CollectFull; 195 friend class VM_G1IncCollectionPause; 196 friend class VMStructs; 197 friend class MutatorAllocRegion; 198 friend class SurvivorGCAllocRegion; 199 friend class OldGCAllocRegion; 200 201 // Closures used in implementation. 202 friend class G1ParCopyHelper; 203 friend class G1IsAliveClosure; 204 friend class G1EvacuateFollowersClosure; 205 friend class G1ParScanThreadState; 206 friend class G1ParScanClosureSuper; 207 friend class G1ParEvacuateFollowersClosure; 208 friend class G1ParTask; 209 friend class G1FreeGarbageRegionClosure; 210 friend class RefineCardTableEntryClosure; 211 friend class G1PrepareCompactClosure; 212 friend class RegionSorter; 213 friend class RegionResetter; 214 friend class CountRCClosure; 215 friend class EvacPopObjClosure; 216 friend class G1ParCleanupCTTask; 217 218 // Other related classes. 219 friend class G1MarkSweep; 220 221 private: 222 // The one and only G1CollectedHeap, so static functions can find it. 223 static G1CollectedHeap* _g1h; 224 225 static size_t _humongous_object_threshold_in_words; 226 227 // Storage for the G1 heap (excludes the permanent generation). 228 VirtualSpace _g1_storage; 229 MemRegion _g1_reserved; 230 231 // The part of _g1_storage that is currently committed. 232 MemRegion _g1_committed; 233 234 // The master free list. It will satisfy all new region allocations. 235 MasterFreeRegionList _free_list; 236 237 // The secondary free list which contains regions that have been 238 // freed up during the cleanup process. This will be appended to the 239 // master free list when appropriate. 240 SecondaryFreeRegionList _secondary_free_list; 241 242 // It keeps track of the humongous regions. 243 MasterHumongousRegionSet _humongous_set; 244 245 // The number of regions we could create by expansion. 246 size_t _expansion_regions; 247 248 // The block offset table for the G1 heap. 249 G1BlockOffsetSharedArray* _bot_shared; 250 251 // Move all of the regions off the free lists, then rebuild those free 252 // lists, before and after full GC. 253 void tear_down_region_lists(); 254 void rebuild_region_lists(); 255 256 // The sequence of all heap regions in the heap. 257 HeapRegionSeq _hrs; 258 259 // Alloc region used to satisfy mutator allocation requests. 260 MutatorAllocRegion _mutator_alloc_region; 261 262 // Alloc region used to satisfy allocation requests by the GC for 263 // survivor objects. 264 SurvivorGCAllocRegion _survivor_gc_alloc_region; 265 266 // Alloc region used to satisfy allocation requests by the GC for 267 // old objects. 268 OldGCAllocRegion _old_gc_alloc_region; 269 270 // The last old region we allocated to during the last GC. 271 // Typically, it is not full so we should re-use it during the next GC. 272 HeapRegion* _retained_old_gc_alloc_region; 273 274 // It resets the mutator alloc region before new allocations can take place. 275 void init_mutator_alloc_region(); 276 277 // It releases the mutator alloc region. 278 void release_mutator_alloc_region(); 279 280 // It initializes the GC alloc regions at the start of a GC. 281 void init_gc_alloc_regions(); 282 283 // It releases the GC alloc regions at the end of a GC. 284 void release_gc_alloc_regions(); 285 286 // It does any cleanup that needs to be done on the GC alloc regions 287 // before a Full GC. 288 void abandon_gc_alloc_regions(); 289 290 // Helper for monitoring and management support. 291 G1MonitoringSupport* _g1mm; 292 293 // Determines PLAB size for a particular allocation purpose. 294 static size_t desired_plab_sz(GCAllocPurpose purpose); 295 296 // Outside of GC pauses, the number of bytes used in all regions other 297 // than the current allocation region. 298 size_t _summary_bytes_used; 299 300 // This is used for a quick test on whether a reference points into 301 // the collection set or not. Basically, we have an array, with one 302 // byte per region, and that byte denotes whether the corresponding 303 // region is in the collection set or not. The entry corresponding 304 // the bottom of the heap, i.e., region 0, is pointed to by 305 // _in_cset_fast_test_base. The _in_cset_fast_test field has been 306 // biased so that it actually points to address 0 of the address 307 // space, to make the test as fast as possible (we can simply shift 308 // the address to address into it, instead of having to subtract the 309 // bottom of the heap from the address before shifting it; basically 310 // it works in the same way the card table works). 311 bool* _in_cset_fast_test; 312 313 // The allocated array used for the fast test on whether a reference 314 // points into the collection set or not. This field is also used to 315 // free the array. 316 bool* _in_cset_fast_test_base; 317 318 // The length of the _in_cset_fast_test_base array. 319 size_t _in_cset_fast_test_length; 320 321 volatile unsigned _gc_time_stamp; 322 323 size_t* _surviving_young_words; 324 325 G1HRPrinter _hr_printer; 326 327 void setup_surviving_young_words(); 328 void update_surviving_young_words(size_t* surv_young_words); 329 void cleanup_surviving_young_words(); 330 331 // It decides whether an explicit GC should start a concurrent cycle 332 // instead of doing a STW GC. Currently, a concurrent cycle is 333 // explicitly started if: 334 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 335 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 336 bool should_do_concurrent_full_gc(GCCause::Cause cause); 337 338 // Keeps track of how many "full collections" (i.e., Full GCs or 339 // concurrent cycles) we have completed. The number of them we have 340 // started is maintained in _total_full_collections in CollectedHeap. 341 volatile unsigned int _full_collections_completed; 342 343 // This is a non-product method that is helpful for testing. It is 344 // called at the end of a GC and artificially expands the heap by 345 // allocating a number of dead regions. This way we can induce very 346 // frequent marking cycles and stress the cleanup / concurrent 347 // cleanup code more (as all the regions that will be allocated by 348 // this method will be found dead by the marking cycle). 349 void allocate_dummy_regions() PRODUCT_RETURN; 350 351 // These are macros so that, if the assert fires, we get the correct 352 // line number, file, etc. 353 354 #define heap_locking_asserts_err_msg(_extra_message_) \ 355 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 356 (_extra_message_), \ 357 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 358 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 359 BOOL_TO_STR(Thread::current()->is_VM_thread())) 360 361 #define assert_heap_locked() \ 362 do { \ 363 assert(Heap_lock->owned_by_self(), \ 364 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \ 365 } while (0) 366 367 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 368 do { \ 369 assert(Heap_lock->owned_by_self() || \ 370 (SafepointSynchronize::is_at_safepoint() && \ 371 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 372 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \ 373 "should be at a safepoint")); \ 374 } while (0) 375 376 #define assert_heap_locked_and_not_at_safepoint() \ 377 do { \ 378 assert(Heap_lock->owned_by_self() && \ 379 !SafepointSynchronize::is_at_safepoint(), \ 380 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \ 381 "should not be at a safepoint")); \ 382 } while (0) 383 384 #define assert_heap_not_locked() \ 385 do { \ 386 assert(!Heap_lock->owned_by_self(), \ 387 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \ 388 } while (0) 389 390 #define assert_heap_not_locked_and_not_at_safepoint() \ 391 do { \ 392 assert(!Heap_lock->owned_by_self() && \ 393 !SafepointSynchronize::is_at_safepoint(), \ 394 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \ 395 "should not be at a safepoint")); \ 396 } while (0) 397 398 #define assert_at_safepoint(_should_be_vm_thread_) \ 399 do { \ 400 assert(SafepointSynchronize::is_at_safepoint() && \ 401 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 402 heap_locking_asserts_err_msg("should be at a safepoint")); \ 403 } while (0) 404 405 #define assert_not_at_safepoint() \ 406 do { \ 407 assert(!SafepointSynchronize::is_at_safepoint(), \ 408 heap_locking_asserts_err_msg("should not be at a safepoint")); \ 409 } while (0) 410 411 protected: 412 413 // The young region list. 414 YoungList* _young_list; 415 416 // The current policy object for the collector. 417 G1CollectorPolicy* _g1_policy; 418 419 // This is the second level of trying to allocate a new region. If 420 // new_region() didn't find a region on the free_list, this call will 421 // check whether there's anything available on the 422 // secondary_free_list and/or wait for more regions to appear on 423 // that list, if _free_regions_coming is set. 424 HeapRegion* new_region_try_secondary_free_list(); 425 426 // Try to allocate a single non-humongous HeapRegion sufficient for 427 // an allocation of the given word_size. If do_expand is true, 428 // attempt to expand the heap if necessary to satisfy the allocation 429 // request. 430 HeapRegion* new_region(size_t word_size, bool do_expand); 431 432 // Attempt to satisfy a humongous allocation request of the given 433 // size by finding a contiguous set of free regions of num_regions 434 // length and remove them from the master free list. Return the 435 // index of the first region or G1_NULL_HRS_INDEX if the search 436 // was unsuccessful. 437 size_t humongous_obj_allocate_find_first(size_t num_regions, 438 size_t word_size); 439 440 // Initialize a contiguous set of free regions of length num_regions 441 // and starting at index first so that they appear as a single 442 // humongous region. 443 HeapWord* humongous_obj_allocate_initialize_regions(size_t first, 444 size_t num_regions, 445 size_t word_size); 446 447 // Attempt to allocate a humongous object of the given size. Return 448 // NULL if unsuccessful. 449 HeapWord* humongous_obj_allocate(size_t word_size); 450 451 // The following two methods, allocate_new_tlab() and 452 // mem_allocate(), are the two main entry points from the runtime 453 // into the G1's allocation routines. They have the following 454 // assumptions: 455 // 456 // * They should both be called outside safepoints. 457 // 458 // * They should both be called without holding the Heap_lock. 459 // 460 // * All allocation requests for new TLABs should go to 461 // allocate_new_tlab(). 462 // 463 // * All non-TLAB allocation requests should go to mem_allocate(). 464 // 465 // * If either call cannot satisfy the allocation request using the 466 // current allocating region, they will try to get a new one. If 467 // this fails, they will attempt to do an evacuation pause and 468 // retry the allocation. 469 // 470 // * If all allocation attempts fail, even after trying to schedule 471 // an evacuation pause, allocate_new_tlab() will return NULL, 472 // whereas mem_allocate() will attempt a heap expansion and/or 473 // schedule a Full GC. 474 // 475 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 476 // should never be called with word_size being humongous. All 477 // humongous allocation requests should go to mem_allocate() which 478 // will satisfy them with a special path. 479 480 virtual HeapWord* allocate_new_tlab(size_t word_size); 481 482 virtual HeapWord* mem_allocate(size_t word_size, 483 bool* gc_overhead_limit_was_exceeded); 484 485 // The following three methods take a gc_count_before_ret 486 // parameter which is used to return the GC count if the method 487 // returns NULL. Given that we are required to read the GC count 488 // while holding the Heap_lock, and these paths will take the 489 // Heap_lock at some point, it's easier to get them to read the GC 490 // count while holding the Heap_lock before they return NULL instead 491 // of the caller (namely: mem_allocate()) having to also take the 492 // Heap_lock just to read the GC count. 493 494 // First-level mutator allocation attempt: try to allocate out of 495 // the mutator alloc region without taking the Heap_lock. This 496 // should only be used for non-humongous allocations. 497 inline HeapWord* attempt_allocation(size_t word_size, 498 unsigned int* gc_count_before_ret); 499 500 // Second-level mutator allocation attempt: take the Heap_lock and 501 // retry the allocation attempt, potentially scheduling a GC 502 // pause. This should only be used for non-humongous allocations. 503 HeapWord* attempt_allocation_slow(size_t word_size, 504 unsigned int* gc_count_before_ret); 505 506 // Takes the Heap_lock and attempts a humongous allocation. It can 507 // potentially schedule a GC pause. 508 HeapWord* attempt_allocation_humongous(size_t word_size, 509 unsigned int* gc_count_before_ret); 510 511 // Allocation attempt that should be called during safepoints (e.g., 512 // at the end of a successful GC). expect_null_mutator_alloc_region 513 // specifies whether the mutator alloc region is expected to be NULL 514 // or not. 515 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 516 bool expect_null_mutator_alloc_region); 517 518 // It dirties the cards that cover the block so that so that the post 519 // write barrier never queues anything when updating objects on this 520 // block. It is assumed (and in fact we assert) that the block 521 // belongs to a young region. 522 inline void dirty_young_block(HeapWord* start, size_t word_size); 523 524 // Allocate blocks during garbage collection. Will ensure an 525 // allocation region, either by picking one or expanding the 526 // heap, and then allocate a block of the given size. The block 527 // may not be a humongous - it must fit into a single heap region. 528 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size); 529 530 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose, 531 HeapRegion* alloc_region, 532 bool par, 533 size_t word_size); 534 535 // Ensure that no further allocations can happen in "r", bearing in mind 536 // that parallel threads might be attempting allocations. 537 void par_allocate_remaining_space(HeapRegion* r); 538 539 // Allocation attempt during GC for a survivor object / PLAB. 540 inline HeapWord* survivor_attempt_allocation(size_t word_size); 541 542 // Allocation attempt during GC for an old object / PLAB. 543 inline HeapWord* old_attempt_allocation(size_t word_size); 544 545 // These methods are the "callbacks" from the G1AllocRegion class. 546 547 // For mutator alloc regions. 548 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 549 void retire_mutator_alloc_region(HeapRegion* alloc_region, 550 size_t allocated_bytes); 551 552 // For GC alloc regions. 553 HeapRegion* new_gc_alloc_region(size_t word_size, size_t count, 554 GCAllocPurpose ap); 555 void retire_gc_alloc_region(HeapRegion* alloc_region, 556 size_t allocated_bytes, GCAllocPurpose ap); 557 558 // - if explicit_gc is true, the GC is for a System.gc() or a heap 559 // inspection request and should collect the entire heap 560 // - if clear_all_soft_refs is true, all soft references should be 561 // cleared during the GC 562 // - if explicit_gc is false, word_size describes the allocation that 563 // the GC should attempt (at least) to satisfy 564 // - it returns false if it is unable to do the collection due to the 565 // GC locker being active, true otherwise 566 bool do_collection(bool explicit_gc, 567 bool clear_all_soft_refs, 568 size_t word_size); 569 570 // Callback from VM_G1CollectFull operation. 571 // Perform a full collection. 572 void do_full_collection(bool clear_all_soft_refs); 573 574 // Resize the heap if necessary after a full collection. If this is 575 // after a collect-for allocation, "word_size" is the allocation size, 576 // and will be considered part of the used portion of the heap. 577 void resize_if_necessary_after_full_collection(size_t word_size); 578 579 // Callback from VM_G1CollectForAllocation operation. 580 // This function does everything necessary/possible to satisfy a 581 // failed allocation request (including collection, expansion, etc.) 582 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded); 583 584 // Attempting to expand the heap sufficiently 585 // to support an allocation of the given "word_size". If 586 // successful, perform the allocation and return the address of the 587 // allocated block, or else "NULL". 588 HeapWord* expand_and_allocate(size_t word_size); 589 590 // Process any reference objects discovered during 591 // an incremental evacuation pause. 592 void process_discovered_references(); 593 594 // Enqueue any remaining discovered references 595 // after processing. 596 void enqueue_discovered_references(); 597 598 public: 599 600 G1MonitoringSupport* g1mm() { return _g1mm; } 601 602 // Expand the garbage-first heap by at least the given size (in bytes!). 603 // Returns true if the heap was expanded by the requested amount; 604 // false otherwise. 605 // (Rounds up to a HeapRegion boundary.) 606 bool expand(size_t expand_bytes); 607 608 // Do anything common to GC's. 609 virtual void gc_prologue(bool full); 610 virtual void gc_epilogue(bool full); 611 612 // We register a region with the fast "in collection set" test. We 613 // simply set to true the array slot corresponding to this region. 614 void register_region_with_in_cset_fast_test(HeapRegion* r) { 615 assert(_in_cset_fast_test_base != NULL, "sanity"); 616 assert(r->in_collection_set(), "invariant"); 617 size_t index = r->hrs_index(); 618 assert(index < _in_cset_fast_test_length, "invariant"); 619 assert(!_in_cset_fast_test_base[index], "invariant"); 620 _in_cset_fast_test_base[index] = true; 621 } 622 623 // This is a fast test on whether a reference points into the 624 // collection set or not. It does not assume that the reference 625 // points into the heap; if it doesn't, it will return false. 626 bool in_cset_fast_test(oop obj) { 627 assert(_in_cset_fast_test != NULL, "sanity"); 628 if (_g1_committed.contains((HeapWord*) obj)) { 629 // no need to subtract the bottom of the heap from obj, 630 // _in_cset_fast_test is biased 631 size_t index = ((size_t) obj) >> HeapRegion::LogOfHRGrainBytes; 632 bool ret = _in_cset_fast_test[index]; 633 // let's make sure the result is consistent with what the slower 634 // test returns 635 assert( ret || !obj_in_cs(obj), "sanity"); 636 assert(!ret || obj_in_cs(obj), "sanity"); 637 return ret; 638 } else { 639 return false; 640 } 641 } 642 643 void clear_cset_fast_test() { 644 assert(_in_cset_fast_test_base != NULL, "sanity"); 645 memset(_in_cset_fast_test_base, false, 646 _in_cset_fast_test_length * sizeof(bool)); 647 } 648 649 // This is called at the end of either a concurrent cycle or a Full 650 // GC to update the number of full collections completed. Those two 651 // can happen in a nested fashion, i.e., we start a concurrent 652 // cycle, a Full GC happens half-way through it which ends first, 653 // and then the cycle notices that a Full GC happened and ends 654 // too. The concurrent parameter is a boolean to help us do a bit 655 // tighter consistency checking in the method. If concurrent is 656 // false, the caller is the inner caller in the nesting (i.e., the 657 // Full GC). If concurrent is true, the caller is the outer caller 658 // in this nesting (i.e., the concurrent cycle). Further nesting is 659 // not currently supported. The end of the this call also notifies 660 // the FullGCCount_lock in case a Java thread is waiting for a full 661 // GC to happen (e.g., it called System.gc() with 662 // +ExplicitGCInvokesConcurrent). 663 void increment_full_collections_completed(bool concurrent); 664 665 unsigned int full_collections_completed() { 666 return _full_collections_completed; 667 } 668 669 G1HRPrinter* hr_printer() { return &_hr_printer; } 670 671 protected: 672 673 // Shrink the garbage-first heap by at most the given size (in bytes!). 674 // (Rounds down to a HeapRegion boundary.) 675 virtual void shrink(size_t expand_bytes); 676 void shrink_helper(size_t expand_bytes); 677 678 #if TASKQUEUE_STATS 679 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 680 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 681 void reset_taskqueue_stats(); 682 #endif // TASKQUEUE_STATS 683 684 // Schedule the VM operation that will do an evacuation pause to 685 // satisfy an allocation request of word_size. *succeeded will 686 // return whether the VM operation was successful (it did do an 687 // evacuation pause) or not (another thread beat us to it or the GC 688 // locker was active). Given that we should not be holding the 689 // Heap_lock when we enter this method, we will pass the 690 // gc_count_before (i.e., total_collections()) as a parameter since 691 // it has to be read while holding the Heap_lock. Currently, both 692 // methods that call do_collection_pause() release the Heap_lock 693 // before the call, so it's easy to read gc_count_before just before. 694 HeapWord* do_collection_pause(size_t word_size, 695 unsigned int gc_count_before, 696 bool* succeeded); 697 698 // The guts of the incremental collection pause, executed by the vm 699 // thread. It returns false if it is unable to do the collection due 700 // to the GC locker being active, true otherwise 701 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 702 703 // Actually do the work of evacuating the collection set. 704 void evacuate_collection_set(); 705 706 // The g1 remembered set of the heap. 707 G1RemSet* _g1_rem_set; 708 // And it's mod ref barrier set, used to track updates for the above. 709 ModRefBarrierSet* _mr_bs; 710 711 // A set of cards that cover the objects for which the Rsets should be updated 712 // concurrently after the collection. 713 DirtyCardQueueSet _dirty_card_queue_set; 714 715 // The Heap Region Rem Set Iterator. 716 HeapRegionRemSetIterator** _rem_set_iterator; 717 718 // The closure used to refine a single card. 719 RefineCardTableEntryClosure* _refine_cte_cl; 720 721 // A function to check the consistency of dirty card logs. 722 void check_ct_logs_at_safepoint(); 723 724 // A DirtyCardQueueSet that is used to hold cards that contain 725 // references into the current collection set. This is used to 726 // update the remembered sets of the regions in the collection 727 // set in the event of an evacuation failure. 728 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 729 730 // After a collection pause, make the regions in the CS into free 731 // regions. 732 void free_collection_set(HeapRegion* cs_head); 733 734 // Abandon the current collection set without recording policy 735 // statistics or updating free lists. 736 void abandon_collection_set(HeapRegion* cs_head); 737 738 // Applies "scan_non_heap_roots" to roots outside the heap, 739 // "scan_rs" to roots inside the heap (having done "set_region" to 740 // indicate the region in which the root resides), and does "scan_perm" 741 // (setting the generation to the perm generation.) If "scan_rs" is 742 // NULL, then this step is skipped. The "worker_i" 743 // param is for use with parallel roots processing, and should be 744 // the "i" of the calling parallel worker thread's work(i) function. 745 // In the sequential case this param will be ignored. 746 void g1_process_strong_roots(bool collecting_perm_gen, 747 SharedHeap::ScanningOption so, 748 OopClosure* scan_non_heap_roots, 749 OopsInHeapRegionClosure* scan_rs, 750 OopsInGenClosure* scan_perm, 751 int worker_i); 752 753 // Apply "blk" to all the weak roots of the system. These include 754 // JNI weak roots, the code cache, system dictionary, symbol table, 755 // string table, and referents of reachable weak refs. 756 void g1_process_weak_roots(OopClosure* root_closure, 757 OopClosure* non_root_closure); 758 759 // Frees a non-humongous region by initializing its contents and 760 // adding it to the free list that's passed as a parameter (this is 761 // usually a local list which will be appended to the master free 762 // list later). The used bytes of freed regions are accumulated in 763 // pre_used. If par is true, the region's RSet will not be freed 764 // up. The assumption is that this will be done later. 765 void free_region(HeapRegion* hr, 766 size_t* pre_used, 767 FreeRegionList* free_list, 768 bool par); 769 770 // Frees a humongous region by collapsing it into individual regions 771 // and calling free_region() for each of them. The freed regions 772 // will be added to the free list that's passed as a parameter (this 773 // is usually a local list which will be appended to the master free 774 // list later). The used bytes of freed regions are accumulated in 775 // pre_used. If par is true, the region's RSet will not be freed 776 // up. The assumption is that this will be done later. 777 void free_humongous_region(HeapRegion* hr, 778 size_t* pre_used, 779 FreeRegionList* free_list, 780 HumongousRegionSet* humongous_proxy_set, 781 bool par); 782 783 // Notifies all the necessary spaces that the committed space has 784 // been updated (either expanded or shrunk). It should be called 785 // after _g1_storage is updated. 786 void update_committed_space(HeapWord* old_end, HeapWord* new_end); 787 788 // The concurrent marker (and the thread it runs in.) 789 ConcurrentMark* _cm; 790 ConcurrentMarkThread* _cmThread; 791 bool _mark_in_progress; 792 793 // The concurrent refiner. 794 ConcurrentG1Refine* _cg1r; 795 796 // The parallel task queues 797 RefToScanQueueSet *_task_queues; 798 799 // True iff a evacuation has failed in the current collection. 800 bool _evacuation_failed; 801 802 // Set the attribute indicating whether evacuation has failed in the 803 // current collection. 804 void set_evacuation_failed(bool b) { _evacuation_failed = b; } 805 806 // Failed evacuations cause some logical from-space objects to have 807 // forwarding pointers to themselves. Reset them. 808 void remove_self_forwarding_pointers(); 809 810 // When one is non-null, so is the other. Together, they each pair is 811 // an object with a preserved mark, and its mark value. 812 GrowableArray<oop>* _objs_with_preserved_marks; 813 GrowableArray<markOop>* _preserved_marks_of_objs; 814 815 // Preserve the mark of "obj", if necessary, in preparation for its mark 816 // word being overwritten with a self-forwarding-pointer. 817 void preserve_mark_if_necessary(oop obj, markOop m); 818 819 // The stack of evac-failure objects left to be scanned. 820 GrowableArray<oop>* _evac_failure_scan_stack; 821 // The closure to apply to evac-failure objects. 822 823 OopsInHeapRegionClosure* _evac_failure_closure; 824 // Set the field above. 825 void 826 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) { 827 _evac_failure_closure = evac_failure_closure; 828 } 829 830 // Push "obj" on the scan stack. 831 void push_on_evac_failure_scan_stack(oop obj); 832 // Process scan stack entries until the stack is empty. 833 void drain_evac_failure_scan_stack(); 834 // True iff an invocation of "drain_scan_stack" is in progress; to 835 // prevent unnecessary recursion. 836 bool _drain_in_progress; 837 838 // Do any necessary initialization for evacuation-failure handling. 839 // "cl" is the closure that will be used to process evac-failure 840 // objects. 841 void init_for_evac_failure(OopsInHeapRegionClosure* cl); 842 // Do any necessary cleanup for evacuation-failure handling data 843 // structures. 844 void finalize_for_evac_failure(); 845 846 // An attempt to evacuate "obj" has failed; take necessary steps. 847 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj); 848 void handle_evacuation_failure_common(oop obj, markOop m); 849 850 // ("Weak") Reference processing support. 851 // 852 // G1 has 2 instances of the referece processor class. One 853 // (_ref_processor_cm) handles reference object discovery 854 // and subsequent processing during concurrent marking cycles. 855 // 856 // The other (_ref_processor_stw) handles reference object 857 // discovery and processing during full GCs and incremental 858 // evacuation pauses. 859 // 860 // During an incremental pause, reference discovery will be 861 // temporarily disabled for _ref_processor_cm and will be 862 // enabled for _ref_processor_stw. At the end of the evacuation 863 // pause references discovered by _ref_processor_stw will be 864 // processed and discovery will be disabled. The previous 865 // setting for reference object discovery for _ref_processor_cm 866 // will be re-instated. 867 // 868 // At the start of marking: 869 // * Discovery by the CM ref processor is verified to be inactive 870 // and it's discovered lists are empty. 871 // * Discovery by the CM ref processor is then enabled. 872 // 873 // At the end of marking: 874 // * Any references on the CM ref processor's discovered 875 // lists are processed (possibly MT). 876 // 877 // At the start of full GC we: 878 // * Disable discovery by the CM ref processor and 879 // empty CM ref processor's discovered lists 880 // (without processing any entries). 881 // * Verify that the STW ref processor is inactive and it's 882 // discovered lists are empty. 883 // * Temporarily set STW ref processor discovery as single threaded. 884 // * Temporarily clear the STW ref processor's _is_alive_non_header 885 // field. 886 // * Finally enable discovery by the STW ref processor. 887 // 888 // The STW ref processor is used to record any discovered 889 // references during the full GC. 890 // 891 // At the end of a full GC we: 892 // * Will enqueue any non-live discovered references on the 893 // STW ref processor's discovered lists. This makes the 894 // STW ref processor inactive by disabling discovery. 895 // * Verify that the CM ref processor is still inactive 896 // and no references have been placed on it's discovered 897 // lists (also checked as a precondition during initial marking). 898 899 // The (stw) reference processor... 900 ReferenceProcessor* _ref_processor_stw; 901 902 // Instance of the is_alive closure for embedding into the 903 // STW reference processor as the _is_alive_non_header field. 904 // The _is_alive_non_header prevents unnecessary additions to 905 // the discovered lists during reference discovery. 906 G1STWIsAliveClosure _is_alive_closure_stw; 907 908 // The (concurrent marking) reference processor... 909 ReferenceProcessor* _ref_processor_cm; 910 911 // Instance of the concurrent mark is_alive closure for embedding 912 // into the Concurrent Marking reference processor as the 913 // _is_alive_non_header field. The _is_alive_non_header 914 // prevents unnecessary additions to the discovered lists 915 // during concurrent discovery. 916 G1CMIsAliveClosure _is_alive_closure_cm; 917 918 enum G1H_process_strong_roots_tasks { 919 G1H_PS_mark_stack_oops_do, 920 G1H_PS_refProcessor_oops_do, 921 // Leave this one last. 922 G1H_PS_NumElements 923 }; 924 925 SubTasksDone* _process_strong_tasks; 926 927 volatile bool _free_regions_coming; 928 929 public: 930 931 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; } 932 933 void set_refine_cte_cl_concurrency(bool concurrent); 934 935 RefToScanQueue *task_queue(int i) const; 936 937 // A set of cards where updates happened during the GC 938 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 939 940 // A DirtyCardQueueSet that is used to hold cards that contain 941 // references into the current collection set. This is used to 942 // update the remembered sets of the regions in the collection 943 // set in the event of an evacuation failure. 944 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 945 { return _into_cset_dirty_card_queue_set; } 946 947 // Create a G1CollectedHeap with the specified policy. 948 // Must call the initialize method afterwards. 949 // May not return if something goes wrong. 950 G1CollectedHeap(G1CollectorPolicy* policy); 951 952 // Initialize the G1CollectedHeap to have the initial and 953 // maximum sizes, permanent generation, and remembered and barrier sets 954 // specified by the policy object. 955 jint initialize(); 956 957 // Initialize weak reference processing. 958 virtual void ref_processing_init(); 959 960 void set_par_threads(int t) { 961 SharedHeap::set_par_threads(t); 962 _process_strong_tasks->set_n_threads(t); 963 } 964 965 virtual CollectedHeap::Name kind() const { 966 return CollectedHeap::G1CollectedHeap; 967 } 968 969 // The current policy object for the collector. 970 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 971 972 // Adaptive size policy. No such thing for g1. 973 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 974 975 // The rem set and barrier set. 976 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 977 ModRefBarrierSet* mr_bs() const { return _mr_bs; } 978 979 // The rem set iterator. 980 HeapRegionRemSetIterator* rem_set_iterator(int i) { 981 return _rem_set_iterator[i]; 982 } 983 984 HeapRegionRemSetIterator* rem_set_iterator() { 985 return _rem_set_iterator[0]; 986 } 987 988 unsigned get_gc_time_stamp() { 989 return _gc_time_stamp; 990 } 991 992 void reset_gc_time_stamp() { 993 _gc_time_stamp = 0; 994 OrderAccess::fence(); 995 } 996 997 void increment_gc_time_stamp() { 998 ++_gc_time_stamp; 999 OrderAccess::fence(); 1000 } 1001 1002 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1003 DirtyCardQueue* into_cset_dcq, 1004 bool concurrent, int worker_i); 1005 1006 // The shared block offset table array. 1007 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1008 1009 // Reference Processing accessors 1010 1011 // The STW reference processor.... 1012 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1013 1014 // The Concurent Marking reference processor... 1015 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1016 1017 virtual size_t capacity() const; 1018 virtual size_t used() const; 1019 // This should be called when we're not holding the heap lock. The 1020 // result might be a bit inaccurate. 1021 size_t used_unlocked() const; 1022 size_t recalculate_used() const; 1023 1024 // These virtual functions do the actual allocation. 1025 // Some heaps may offer a contiguous region for shared non-blocking 1026 // allocation, via inlined code (by exporting the address of the top and 1027 // end fields defining the extent of the contiguous allocation region.) 1028 // But G1CollectedHeap doesn't yet support this. 1029 1030 // Return an estimate of the maximum allocation that could be performed 1031 // without triggering any collection or expansion activity. In a 1032 // generational collector, for example, this is probably the largest 1033 // allocation that could be supported (without expansion) in the youngest 1034 // generation. It is "unsafe" because no locks are taken; the result 1035 // should be treated as an approximation, not a guarantee, for use in 1036 // heuristic resizing decisions. 1037 virtual size_t unsafe_max_alloc(); 1038 1039 virtual bool is_maximal_no_gc() const { 1040 return _g1_storage.uncommitted_size() == 0; 1041 } 1042 1043 // The total number of regions in the heap. 1044 size_t n_regions() { return _hrs.length(); } 1045 1046 // The max number of regions in the heap. 1047 size_t max_regions() { return _hrs.max_length(); } 1048 1049 // The number of regions that are completely free. 1050 size_t free_regions() { return _free_list.length(); } 1051 1052 // The number of regions that are not completely free. 1053 size_t used_regions() { return n_regions() - free_regions(); } 1054 1055 // The number of regions available for "regular" expansion. 1056 size_t expansion_regions() { return _expansion_regions; } 1057 1058 // Factory method for HeapRegion instances. It will return NULL if 1059 // the allocation fails. 1060 HeapRegion* new_heap_region(size_t hrs_index, HeapWord* bottom); 1061 1062 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1063 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1064 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1065 void verify_dirty_young_regions() PRODUCT_RETURN; 1066 1067 // verify_region_sets() performs verification over the region 1068 // lists. It will be compiled in the product code to be used when 1069 // necessary (i.e., during heap verification). 1070 void verify_region_sets(); 1071 1072 // verify_region_sets_optional() is planted in the code for 1073 // list verification in non-product builds (and it can be enabled in 1074 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1). 1075 #if HEAP_REGION_SET_FORCE_VERIFY 1076 void verify_region_sets_optional() { 1077 verify_region_sets(); 1078 } 1079 #else // HEAP_REGION_SET_FORCE_VERIFY 1080 void verify_region_sets_optional() { } 1081 #endif // HEAP_REGION_SET_FORCE_VERIFY 1082 1083 #ifdef ASSERT 1084 bool is_on_master_free_list(HeapRegion* hr) { 1085 return hr->containing_set() == &_free_list; 1086 } 1087 1088 bool is_in_humongous_set(HeapRegion* hr) { 1089 return hr->containing_set() == &_humongous_set; 1090 } 1091 #endif // ASSERT 1092 1093 // Wrapper for the region list operations that can be called from 1094 // methods outside this class. 1095 1096 void secondary_free_list_add_as_tail(FreeRegionList* list) { 1097 _secondary_free_list.add_as_tail(list); 1098 } 1099 1100 void append_secondary_free_list() { 1101 _free_list.add_as_head(&_secondary_free_list); 1102 } 1103 1104 void append_secondary_free_list_if_not_empty_with_lock() { 1105 // If the secondary free list looks empty there's no reason to 1106 // take the lock and then try to append it. 1107 if (!_secondary_free_list.is_empty()) { 1108 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1109 append_secondary_free_list(); 1110 } 1111 } 1112 1113 void set_free_regions_coming(); 1114 void reset_free_regions_coming(); 1115 bool free_regions_coming() { return _free_regions_coming; } 1116 void wait_while_free_regions_coming(); 1117 1118 // Perform a collection of the heap; intended for use in implementing 1119 // "System.gc". This probably implies as full a collection as the 1120 // "CollectedHeap" supports. 1121 virtual void collect(GCCause::Cause cause); 1122 1123 // The same as above but assume that the caller holds the Heap_lock. 1124 void collect_locked(GCCause::Cause cause); 1125 1126 // This interface assumes that it's being called by the 1127 // vm thread. It collects the heap assuming that the 1128 // heap lock is already held and that we are executing in 1129 // the context of the vm thread. 1130 virtual void collect_as_vm_thread(GCCause::Cause cause); 1131 1132 // True iff a evacuation has failed in the most-recent collection. 1133 bool evacuation_failed() { return _evacuation_failed; } 1134 1135 // It will free a region if it has allocated objects in it that are 1136 // all dead. It calls either free_region() or 1137 // free_humongous_region() depending on the type of the region that 1138 // is passed to it. 1139 void free_region_if_empty(HeapRegion* hr, 1140 size_t* pre_used, 1141 FreeRegionList* free_list, 1142 HumongousRegionSet* humongous_proxy_set, 1143 HRRSCleanupTask* hrrs_cleanup_task, 1144 bool par); 1145 1146 // It appends the free list to the master free list and updates the 1147 // master humongous list according to the contents of the proxy 1148 // list. It also adjusts the total used bytes according to pre_used 1149 // (if par is true, it will do so by taking the ParGCRareEvent_lock). 1150 void update_sets_after_freeing_regions(size_t pre_used, 1151 FreeRegionList* free_list, 1152 HumongousRegionSet* humongous_proxy_set, 1153 bool par); 1154 1155 // Returns "TRUE" iff "p" points into the allocated area of the heap. 1156 virtual bool is_in(const void* p) const; 1157 1158 // Return "TRUE" iff the given object address is within the collection 1159 // set. 1160 inline bool obj_in_cs(oop obj); 1161 1162 // Return "TRUE" iff the given object address is in the reserved 1163 // region of g1 (excluding the permanent generation). 1164 bool is_in_g1_reserved(const void* p) const { 1165 return _g1_reserved.contains(p); 1166 } 1167 1168 // Returns a MemRegion that corresponds to the space that has been 1169 // reserved for the heap 1170 MemRegion g1_reserved() { 1171 return _g1_reserved; 1172 } 1173 1174 // Returns a MemRegion that corresponds to the space that has been 1175 // committed in the heap 1176 MemRegion g1_committed() { 1177 return _g1_committed; 1178 } 1179 1180 virtual bool is_in_closed_subset(const void* p) const; 1181 1182 // This resets the card table to all zeros. It is used after 1183 // a collection pause which used the card table to claim cards. 1184 void cleanUpCardTable(); 1185 1186 // Iteration functions. 1187 1188 // Iterate over all the ref-containing fields of all objects, calling 1189 // "cl.do_oop" on each. 1190 virtual void oop_iterate(OopClosure* cl) { 1191 oop_iterate(cl, true); 1192 } 1193 void oop_iterate(OopClosure* cl, bool do_perm); 1194 1195 // Same as above, restricted to a memory region. 1196 virtual void oop_iterate(MemRegion mr, OopClosure* cl) { 1197 oop_iterate(mr, cl, true); 1198 } 1199 void oop_iterate(MemRegion mr, OopClosure* cl, bool do_perm); 1200 1201 // Iterate over all objects, calling "cl.do_object" on each. 1202 virtual void object_iterate(ObjectClosure* cl) { 1203 object_iterate(cl, true); 1204 } 1205 virtual void safe_object_iterate(ObjectClosure* cl) { 1206 object_iterate(cl, true); 1207 } 1208 void object_iterate(ObjectClosure* cl, bool do_perm); 1209 1210 // Iterate over all objects allocated since the last collection, calling 1211 // "cl.do_object" on each. The heap must have been initialized properly 1212 // to support this function, or else this call will fail. 1213 virtual void object_iterate_since_last_GC(ObjectClosure* cl); 1214 1215 // Iterate over all spaces in use in the heap, in ascending address order. 1216 virtual void space_iterate(SpaceClosure* cl); 1217 1218 // Iterate over heap regions, in address order, terminating the 1219 // iteration early if the "doHeapRegion" method returns "true". 1220 void heap_region_iterate(HeapRegionClosure* blk) const; 1221 1222 // Iterate over heap regions starting with r (or the first region if "r" 1223 // is NULL), in address order, terminating early if the "doHeapRegion" 1224 // method returns "true". 1225 void heap_region_iterate_from(HeapRegion* r, HeapRegionClosure* blk) const; 1226 1227 // Return the region with the given index. It assumes the index is valid. 1228 HeapRegion* region_at(size_t index) const { return _hrs.at(index); } 1229 1230 // Divide the heap region sequence into "chunks" of some size (the number 1231 // of regions divided by the number of parallel threads times some 1232 // overpartition factor, currently 4). Assumes that this will be called 1233 // in parallel by ParallelGCThreads worker threads with discinct worker 1234 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel 1235 // calls will use the same "claim_value", and that that claim value is 1236 // different from the claim_value of any heap region before the start of 1237 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by 1238 // attempting to claim the first region in each chunk, and, if 1239 // successful, applying the closure to each region in the chunk (and 1240 // setting the claim value of the second and subsequent regions of the 1241 // chunk.) For now requires that "doHeapRegion" always returns "false", 1242 // i.e., that a closure never attempt to abort a traversal. 1243 void heap_region_par_iterate_chunked(HeapRegionClosure* blk, 1244 int worker, 1245 jint claim_value); 1246 1247 // It resets all the region claim values to the default. 1248 void reset_heap_region_claim_values(); 1249 1250 #ifdef ASSERT 1251 bool check_heap_region_claim_values(jint claim_value); 1252 #endif // ASSERT 1253 1254 // Iterate over the regions (if any) in the current collection set. 1255 void collection_set_iterate(HeapRegionClosure* blk); 1256 1257 // As above but starting from region r 1258 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1259 1260 // Returns the first (lowest address) compactible space in the heap. 1261 virtual CompactibleSpace* first_compactible_space(); 1262 1263 // A CollectedHeap will contain some number of spaces. This finds the 1264 // space containing a given address, or else returns NULL. 1265 virtual Space* space_containing(const void* addr) const; 1266 1267 // A G1CollectedHeap will contain some number of heap regions. This 1268 // finds the region containing a given address, or else returns NULL. 1269 template <class T> 1270 inline HeapRegion* heap_region_containing(const T addr) const; 1271 1272 // Like the above, but requires "addr" to be in the heap (to avoid a 1273 // null-check), and unlike the above, may return an continuing humongous 1274 // region. 1275 template <class T> 1276 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1277 1278 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1279 // each address in the (reserved) heap is a member of exactly 1280 // one block. The defining characteristic of a block is that it is 1281 // possible to find its size, and thus to progress forward to the next 1282 // block. (Blocks may be of different sizes.) Thus, blocks may 1283 // represent Java objects, or they might be free blocks in a 1284 // free-list-based heap (or subheap), as long as the two kinds are 1285 // distinguishable and the size of each is determinable. 1286 1287 // Returns the address of the start of the "block" that contains the 1288 // address "addr". We say "blocks" instead of "object" since some heaps 1289 // may not pack objects densely; a chunk may either be an object or a 1290 // non-object. 1291 virtual HeapWord* block_start(const void* addr) const; 1292 1293 // Requires "addr" to be the start of a chunk, and returns its size. 1294 // "addr + size" is required to be the start of a new chunk, or the end 1295 // of the active area of the heap. 1296 virtual size_t block_size(const HeapWord* addr) const; 1297 1298 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1299 // the block is an object. 1300 virtual bool block_is_obj(const HeapWord* addr) const; 1301 1302 // Does this heap support heap inspection? (+PrintClassHistogram) 1303 virtual bool supports_heap_inspection() const { return true; } 1304 1305 // Section on thread-local allocation buffers (TLABs) 1306 // See CollectedHeap for semantics. 1307 1308 virtual bool supports_tlab_allocation() const; 1309 virtual size_t tlab_capacity(Thread* thr) const; 1310 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const; 1311 1312 // Can a compiler initialize a new object without store barriers? 1313 // This permission only extends from the creation of a new object 1314 // via a TLAB up to the first subsequent safepoint. If such permission 1315 // is granted for this heap type, the compiler promises to call 1316 // defer_store_barrier() below on any slow path allocation of 1317 // a new object for which such initializing store barriers will 1318 // have been elided. G1, like CMS, allows this, but should be 1319 // ready to provide a compensating write barrier as necessary 1320 // if that storage came out of a non-young region. The efficiency 1321 // of this implementation depends crucially on being able to 1322 // answer very efficiently in constant time whether a piece of 1323 // storage in the heap comes from a young region or not. 1324 // See ReduceInitialCardMarks. 1325 virtual bool can_elide_tlab_store_barriers() const { 1326 // 6920090: Temporarily disabled, because of lingering 1327 // instabilities related to RICM with G1. In the 1328 // interim, the option ReduceInitialCardMarksForG1 1329 // below is left solely as a debugging device at least 1330 // until 6920109 fixes the instabilities. 1331 return ReduceInitialCardMarksForG1; 1332 } 1333 1334 virtual bool card_mark_must_follow_store() const { 1335 return true; 1336 } 1337 1338 bool is_in_young(const oop obj) { 1339 HeapRegion* hr = heap_region_containing(obj); 1340 return hr != NULL && hr->is_young(); 1341 } 1342 1343 #ifdef ASSERT 1344 virtual bool is_in_partial_collection(const void* p); 1345 #endif 1346 1347 virtual bool is_scavengable(const void* addr); 1348 1349 // We don't need barriers for initializing stores to objects 1350 // in the young gen: for the SATB pre-barrier, there is no 1351 // pre-value that needs to be remembered; for the remembered-set 1352 // update logging post-barrier, we don't maintain remembered set 1353 // information for young gen objects. 1354 virtual bool can_elide_initializing_store_barrier(oop new_obj) { 1355 // Re 6920090, 6920109 above. 1356 assert(ReduceInitialCardMarksForG1, "Else cannot be here"); 1357 return is_in_young(new_obj); 1358 } 1359 1360 // Can a compiler elide a store barrier when it writes 1361 // a permanent oop into the heap? Applies when the compiler 1362 // is storing x to the heap, where x->is_perm() is true. 1363 virtual bool can_elide_permanent_oop_store_barriers() const { 1364 // At least until perm gen collection is also G1-ified, at 1365 // which point this should return false. 1366 return true; 1367 } 1368 1369 // Returns "true" iff the given word_size is "very large". 1370 static bool isHumongous(size_t word_size) { 1371 // Note this has to be strictly greater-than as the TLABs 1372 // are capped at the humongous thresold and we want to 1373 // ensure that we don't try to allocate a TLAB as 1374 // humongous and that we don't allocate a humongous 1375 // object in a TLAB. 1376 return word_size > _humongous_object_threshold_in_words; 1377 } 1378 1379 // Update mod union table with the set of dirty cards. 1380 void updateModUnion(); 1381 1382 // Set the mod union bits corresponding to the given memRegion. Note 1383 // that this is always a safe operation, since it doesn't clear any 1384 // bits. 1385 void markModUnionRange(MemRegion mr); 1386 1387 // Records the fact that a marking phase is no longer in progress. 1388 void set_marking_complete() { 1389 _mark_in_progress = false; 1390 } 1391 void set_marking_started() { 1392 _mark_in_progress = true; 1393 } 1394 bool mark_in_progress() { 1395 return _mark_in_progress; 1396 } 1397 1398 // Print the maximum heap capacity. 1399 virtual size_t max_capacity() const; 1400 1401 virtual jlong millis_since_last_gc(); 1402 1403 // Perform any cleanup actions necessary before allowing a verification. 1404 virtual void prepare_for_verify(); 1405 1406 // Perform verification. 1407 1408 // vo == UsePrevMarking -> use "prev" marking information, 1409 // vo == UseNextMarking -> use "next" marking information 1410 // vo == UseMarkWord -> use the mark word in the object header 1411 // 1412 // NOTE: Only the "prev" marking information is guaranteed to be 1413 // consistent most of the time, so most calls to this should use 1414 // vo == UsePrevMarking. 1415 // Currently, there is only one case where this is called with 1416 // vo == UseNextMarking, which is to verify the "next" marking 1417 // information at the end of remark. 1418 // Currently there is only one place where this is called with 1419 // vo == UseMarkWord, which is to verify the marking during a 1420 // full GC. 1421 void verify(bool allow_dirty, bool silent, VerifyOption vo); 1422 1423 // Override; it uses the "prev" marking information 1424 virtual void verify(bool allow_dirty, bool silent); 1425 // Default behavior by calling print(tty); 1426 virtual void print() const; 1427 // This calls print_on(st, PrintHeapAtGCExtended). 1428 virtual void print_on(outputStream* st) const; 1429 // If extended is true, it will print out information for all 1430 // regions in the heap by calling print_on_extended(st). 1431 virtual void print_on(outputStream* st, bool extended) const; 1432 virtual void print_on_extended(outputStream* st) const; 1433 1434 virtual void print_gc_threads_on(outputStream* st) const; 1435 virtual void gc_threads_do(ThreadClosure* tc) const; 1436 1437 // Override 1438 void print_tracing_info() const; 1439 1440 // The following two methods are helpful for debugging RSet issues. 1441 void print_cset_rsets() PRODUCT_RETURN; 1442 void print_all_rsets() PRODUCT_RETURN; 1443 1444 // Convenience function to be used in situations where the heap type can be 1445 // asserted to be this type. 1446 static G1CollectedHeap* heap(); 1447 1448 void empty_young_list(); 1449 1450 void set_region_short_lived_locked(HeapRegion* hr); 1451 // add appropriate methods for any other surv rate groups 1452 1453 YoungList* young_list() { return _young_list; } 1454 1455 // debugging 1456 bool check_young_list_well_formed() { 1457 return _young_list->check_list_well_formed(); 1458 } 1459 1460 bool check_young_list_empty(bool check_heap, 1461 bool check_sample = true); 1462 1463 // *** Stuff related to concurrent marking. It's not clear to me that so 1464 // many of these need to be public. 1465 1466 // The functions below are helper functions that a subclass of 1467 // "CollectedHeap" can use in the implementation of its virtual 1468 // functions. 1469 // This performs a concurrent marking of the live objects in a 1470 // bitmap off to the side. 1471 void doConcurrentMark(); 1472 1473 bool isMarkedPrev(oop obj) const; 1474 bool isMarkedNext(oop obj) const; 1475 1476 // vo == UsePrevMarking -> use "prev" marking information, 1477 // vo == UseNextMarking -> use "next" marking information, 1478 // vo == UseMarkWord -> use mark word from object header 1479 bool is_obj_dead_cond(const oop obj, 1480 const HeapRegion* hr, 1481 const VerifyOption vo) const { 1482 1483 switch (vo) { 1484 case VerifyOption_G1UsePrevMarking: 1485 return is_obj_dead(obj, hr); 1486 case VerifyOption_G1UseNextMarking: 1487 return is_obj_ill(obj, hr); 1488 default: 1489 assert(vo == VerifyOption_G1UseMarkWord, "must be"); 1490 return !obj->is_gc_marked(); 1491 } 1492 } 1493 1494 // Determine if an object is dead, given the object and also 1495 // the region to which the object belongs. An object is dead 1496 // iff a) it was not allocated since the last mark and b) it 1497 // is not marked. 1498 1499 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1500 return 1501 !hr->obj_allocated_since_prev_marking(obj) && 1502 !isMarkedPrev(obj); 1503 } 1504 1505 // This is used when copying an object to survivor space. 1506 // If the object is marked live, then we mark the copy live. 1507 // If the object is allocated since the start of this mark 1508 // cycle, then we mark the copy live. 1509 // If the object has been around since the previous mark 1510 // phase, and hasn't been marked yet during this phase, 1511 // then we don't mark it, we just wait for the 1512 // current marking cycle to get to it. 1513 1514 // This function returns true when an object has been 1515 // around since the previous marking and hasn't yet 1516 // been marked during this marking. 1517 1518 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1519 return 1520 !hr->obj_allocated_since_next_marking(obj) && 1521 !isMarkedNext(obj); 1522 } 1523 1524 // Determine if an object is dead, given only the object itself. 1525 // This will find the region to which the object belongs and 1526 // then call the region version of the same function. 1527 1528 // Added if it is in permanent gen it isn't dead. 1529 // Added if it is NULL it isn't dead. 1530 1531 // vo == UsePrevMarking -> use "prev" marking information, 1532 // vo == UseNextMarking -> use "next" marking information, 1533 // vo == UseMarkWord -> use mark word from object header 1534 bool is_obj_dead_cond(const oop obj, 1535 const VerifyOption vo) const { 1536 1537 switch (vo) { 1538 case VerifyOption_G1UsePrevMarking: 1539 return is_obj_dead(obj); 1540 case VerifyOption_G1UseNextMarking: 1541 return is_obj_ill(obj); 1542 default: 1543 assert(vo == VerifyOption_G1UseMarkWord, "must be"); 1544 return !obj->is_gc_marked(); 1545 } 1546 } 1547 1548 bool is_obj_dead(const oop obj) const { 1549 const HeapRegion* hr = heap_region_containing(obj); 1550 if (hr == NULL) { 1551 if (Universe::heap()->is_in_permanent(obj)) 1552 return false; 1553 else if (obj == NULL) return false; 1554 else return true; 1555 } 1556 else return is_obj_dead(obj, hr); 1557 } 1558 1559 bool is_obj_ill(const oop obj) const { 1560 const HeapRegion* hr = heap_region_containing(obj); 1561 if (hr == NULL) { 1562 if (Universe::heap()->is_in_permanent(obj)) 1563 return false; 1564 else if (obj == NULL) return false; 1565 else return true; 1566 } 1567 else return is_obj_ill(obj, hr); 1568 } 1569 1570 // The following is just to alert the verification code 1571 // that a full collection has occurred and that the 1572 // remembered sets are no longer up to date. 1573 bool _full_collection; 1574 void set_full_collection() { _full_collection = true;} 1575 void clear_full_collection() {_full_collection = false;} 1576 bool full_collection() {return _full_collection;} 1577 1578 ConcurrentMark* concurrent_mark() const { return _cm; } 1579 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1580 1581 // The dirty cards region list is used to record a subset of regions 1582 // whose cards need clearing. The list if populated during the 1583 // remembered set scanning and drained during the card table 1584 // cleanup. Although the methods are reentrant, population/draining 1585 // phases must not overlap. For synchronization purposes the last 1586 // element on the list points to itself. 1587 HeapRegion* _dirty_cards_region_list; 1588 void push_dirty_cards_region(HeapRegion* hr); 1589 HeapRegion* pop_dirty_cards_region(); 1590 1591 public: 1592 void stop_conc_gc_threads(); 1593 1594 // <NEW PREDICTION> 1595 1596 double predict_region_elapsed_time_ms(HeapRegion* hr, bool young); 1597 void check_if_region_is_too_expensive(double predicted_time_ms); 1598 size_t pending_card_num(); 1599 size_t max_pending_card_num(); 1600 size_t cards_scanned(); 1601 1602 // </NEW PREDICTION> 1603 1604 protected: 1605 size_t _max_heap_capacity; 1606 }; 1607 1608 #define use_local_bitmaps 1 1609 #define verify_local_bitmaps 0 1610 #define oop_buffer_length 256 1611 1612 #ifndef PRODUCT 1613 class GCLabBitMap; 1614 class GCLabBitMapClosure: public BitMapClosure { 1615 private: 1616 ConcurrentMark* _cm; 1617 GCLabBitMap* _bitmap; 1618 1619 public: 1620 GCLabBitMapClosure(ConcurrentMark* cm, 1621 GCLabBitMap* bitmap) { 1622 _cm = cm; 1623 _bitmap = bitmap; 1624 } 1625 1626 virtual bool do_bit(size_t offset); 1627 }; 1628 #endif // !PRODUCT 1629 1630 class GCLabBitMap: public BitMap { 1631 private: 1632 ConcurrentMark* _cm; 1633 1634 int _shifter; 1635 size_t _bitmap_word_covers_words; 1636 1637 // beginning of the heap 1638 HeapWord* _heap_start; 1639 1640 // this is the actual start of the GCLab 1641 HeapWord* _real_start_word; 1642 1643 // this is the actual end of the GCLab 1644 HeapWord* _real_end_word; 1645 1646 // this is the first word, possibly located before the actual start 1647 // of the GCLab, that corresponds to the first bit of the bitmap 1648 HeapWord* _start_word; 1649 1650 // size of a GCLab in words 1651 size_t _gclab_word_size; 1652 1653 static int shifter() { 1654 return MinObjAlignment - 1; 1655 } 1656 1657 // how many heap words does a single bitmap word corresponds to? 1658 static size_t bitmap_word_covers_words() { 1659 return BitsPerWord << shifter(); 1660 } 1661 1662 size_t gclab_word_size() const { 1663 return _gclab_word_size; 1664 } 1665 1666 // Calculates actual GCLab size in words 1667 size_t gclab_real_word_size() const { 1668 return bitmap_size_in_bits(pointer_delta(_real_end_word, _start_word)) 1669 / BitsPerWord; 1670 } 1671 1672 static size_t bitmap_size_in_bits(size_t gclab_word_size) { 1673 size_t bits_in_bitmap = gclab_word_size >> shifter(); 1674 // We are going to ensure that the beginning of a word in this 1675 // bitmap also corresponds to the beginning of a word in the 1676 // global marking bitmap. To handle the case where a GCLab 1677 // starts from the middle of the bitmap, we need to add enough 1678 // space (i.e. up to a bitmap word) to ensure that we have 1679 // enough bits in the bitmap. 1680 return bits_in_bitmap + BitsPerWord - 1; 1681 } 1682 public: 1683 GCLabBitMap(HeapWord* heap_start, size_t gclab_word_size) 1684 : BitMap(bitmap_size_in_bits(gclab_word_size)), 1685 _cm(G1CollectedHeap::heap()->concurrent_mark()), 1686 _shifter(shifter()), 1687 _bitmap_word_covers_words(bitmap_word_covers_words()), 1688 _heap_start(heap_start), 1689 _gclab_word_size(gclab_word_size), 1690 _real_start_word(NULL), 1691 _real_end_word(NULL), 1692 _start_word(NULL) 1693 { 1694 guarantee( size_in_words() >= bitmap_size_in_words(), 1695 "just making sure"); 1696 } 1697 1698 inline unsigned heapWordToOffset(HeapWord* addr) { 1699 unsigned offset = (unsigned) pointer_delta(addr, _start_word) >> _shifter; 1700 assert(offset < size(), "offset should be within bounds"); 1701 return offset; 1702 } 1703 1704 inline HeapWord* offsetToHeapWord(size_t offset) { 1705 HeapWord* addr = _start_word + (offset << _shifter); 1706 assert(_real_start_word <= addr && addr < _real_end_word, "invariant"); 1707 return addr; 1708 } 1709 1710 bool fields_well_formed() { 1711 bool ret1 = (_real_start_word == NULL) && 1712 (_real_end_word == NULL) && 1713 (_start_word == NULL); 1714 if (ret1) 1715 return true; 1716 1717 bool ret2 = _real_start_word >= _start_word && 1718 _start_word < _real_end_word && 1719 (_real_start_word + _gclab_word_size) == _real_end_word && 1720 (_start_word + _gclab_word_size + _bitmap_word_covers_words) 1721 > _real_end_word; 1722 return ret2; 1723 } 1724 1725 inline bool mark(HeapWord* addr) { 1726 guarantee(use_local_bitmaps, "invariant"); 1727 assert(fields_well_formed(), "invariant"); 1728 1729 if (addr >= _real_start_word && addr < _real_end_word) { 1730 assert(!isMarked(addr), "should not have already been marked"); 1731 1732 // first mark it on the bitmap 1733 at_put(heapWordToOffset(addr), true); 1734 1735 return true; 1736 } else { 1737 return false; 1738 } 1739 } 1740 1741 inline bool isMarked(HeapWord* addr) { 1742 guarantee(use_local_bitmaps, "invariant"); 1743 assert(fields_well_formed(), "invariant"); 1744 1745 return at(heapWordToOffset(addr)); 1746 } 1747 1748 void set_buffer(HeapWord* start) { 1749 guarantee(use_local_bitmaps, "invariant"); 1750 clear(); 1751 1752 assert(start != NULL, "invariant"); 1753 _real_start_word = start; 1754 _real_end_word = start + _gclab_word_size; 1755 1756 size_t diff = 1757 pointer_delta(start, _heap_start) % _bitmap_word_covers_words; 1758 _start_word = start - diff; 1759 1760 assert(fields_well_formed(), "invariant"); 1761 } 1762 1763 #ifndef PRODUCT 1764 void verify() { 1765 // verify that the marks have been propagated 1766 GCLabBitMapClosure cl(_cm, this); 1767 iterate(&cl); 1768 } 1769 #endif // PRODUCT 1770 1771 void retire() { 1772 guarantee(use_local_bitmaps, "invariant"); 1773 assert(fields_well_formed(), "invariant"); 1774 1775 if (_start_word != NULL) { 1776 CMBitMap* mark_bitmap = _cm->nextMarkBitMap(); 1777 1778 // this means that the bitmap was set up for the GCLab 1779 assert(_real_start_word != NULL && _real_end_word != NULL, "invariant"); 1780 1781 mark_bitmap->mostly_disjoint_range_union(this, 1782 0, // always start from the start of the bitmap 1783 _start_word, 1784 gclab_real_word_size()); 1785 _cm->grayRegionIfNecessary(MemRegion(_real_start_word, _real_end_word)); 1786 1787 #ifndef PRODUCT 1788 if (use_local_bitmaps && verify_local_bitmaps) 1789 verify(); 1790 #endif // PRODUCT 1791 } else { 1792 assert(_real_start_word == NULL && _real_end_word == NULL, "invariant"); 1793 } 1794 } 1795 1796 size_t bitmap_size_in_words() const { 1797 return (bitmap_size_in_bits(gclab_word_size()) + BitsPerWord - 1) / BitsPerWord; 1798 } 1799 1800 }; 1801 1802 class G1ParGCAllocBuffer: public ParGCAllocBuffer { 1803 private: 1804 bool _retired; 1805 bool _should_mark_objects; 1806 GCLabBitMap _bitmap; 1807 1808 public: 1809 G1ParGCAllocBuffer(size_t gclab_word_size); 1810 1811 inline bool mark(HeapWord* addr) { 1812 guarantee(use_local_bitmaps, "invariant"); 1813 assert(_should_mark_objects, "invariant"); 1814 return _bitmap.mark(addr); 1815 } 1816 1817 inline void set_buf(HeapWord* buf) { 1818 if (use_local_bitmaps && _should_mark_objects) { 1819 _bitmap.set_buffer(buf); 1820 } 1821 ParGCAllocBuffer::set_buf(buf); 1822 _retired = false; 1823 } 1824 1825 inline void retire(bool end_of_gc, bool retain) { 1826 if (_retired) 1827 return; 1828 if (use_local_bitmaps && _should_mark_objects) { 1829 _bitmap.retire(); 1830 } 1831 ParGCAllocBuffer::retire(end_of_gc, retain); 1832 _retired = true; 1833 } 1834 }; 1835 1836 class G1ParScanThreadState : public StackObj { 1837 protected: 1838 G1CollectedHeap* _g1h; 1839 RefToScanQueue* _refs; 1840 DirtyCardQueue _dcq; 1841 CardTableModRefBS* _ct_bs; 1842 G1RemSet* _g1_rem; 1843 1844 G1ParGCAllocBuffer _surviving_alloc_buffer; 1845 G1ParGCAllocBuffer _tenured_alloc_buffer; 1846 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount]; 1847 ageTable _age_table; 1848 1849 size_t _alloc_buffer_waste; 1850 size_t _undo_waste; 1851 1852 OopsInHeapRegionClosure* _evac_failure_cl; 1853 G1ParScanHeapEvacClosure* _evac_cl; 1854 G1ParScanPartialArrayClosure* _partial_scan_cl; 1855 1856 int _hash_seed; 1857 int _queue_num; 1858 1859 size_t _term_attempts; 1860 1861 double _start; 1862 double _start_strong_roots; 1863 double _strong_roots_time; 1864 double _start_term; 1865 double _term_time; 1866 1867 // Map from young-age-index (0 == not young, 1 is youngest) to 1868 // surviving words. base is what we get back from the malloc call 1869 size_t* _surviving_young_words_base; 1870 // this points into the array, as we use the first few entries for padding 1871 size_t* _surviving_young_words; 1872 1873 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t)) 1874 1875 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; } 1876 1877 void add_to_undo_waste(size_t waste) { _undo_waste += waste; } 1878 1879 DirtyCardQueue& dirty_card_queue() { return _dcq; } 1880 CardTableModRefBS* ctbs() { return _ct_bs; } 1881 1882 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) { 1883 if (!from->is_survivor()) { 1884 _g1_rem->par_write_ref(from, p, tid); 1885 } 1886 } 1887 1888 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) { 1889 // If the new value of the field points to the same region or 1890 // is the to-space, we don't need to include it in the Rset updates. 1891 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) { 1892 size_t card_index = ctbs()->index_for(p); 1893 // If the card hasn't been added to the buffer, do it. 1894 if (ctbs()->mark_card_deferred(card_index)) { 1895 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index)); 1896 } 1897 } 1898 } 1899 1900 public: 1901 G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num); 1902 1903 ~G1ParScanThreadState() { 1904 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base); 1905 } 1906 1907 RefToScanQueue* refs() { return _refs; } 1908 ageTable* age_table() { return &_age_table; } 1909 1910 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) { 1911 return _alloc_buffers[purpose]; 1912 } 1913 1914 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; } 1915 size_t undo_waste() const { return _undo_waste; } 1916 1917 #ifdef ASSERT 1918 bool verify_ref(narrowOop* ref) const; 1919 bool verify_ref(oop* ref) const; 1920 bool verify_task(StarTask ref) const; 1921 #endif // ASSERT 1922 1923 template <class T> void push_on_queue(T* ref) { 1924 assert(verify_ref(ref), "sanity"); 1925 refs()->push(ref); 1926 } 1927 1928 template <class T> void update_rs(HeapRegion* from, T* p, int tid) { 1929 if (G1DeferredRSUpdate) { 1930 deferred_rs_update(from, p, tid); 1931 } else { 1932 immediate_rs_update(from, p, tid); 1933 } 1934 } 1935 1936 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) { 1937 1938 HeapWord* obj = NULL; 1939 size_t gclab_word_size = _g1h->desired_plab_sz(purpose); 1940 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) { 1941 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose); 1942 assert(gclab_word_size == alloc_buf->word_sz(), 1943 "dynamic resizing is not supported"); 1944 add_to_alloc_buffer_waste(alloc_buf->words_remaining()); 1945 alloc_buf->retire(false, false); 1946 1947 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size); 1948 if (buf == NULL) return NULL; // Let caller handle allocation failure. 1949 // Otherwise. 1950 alloc_buf->set_buf(buf); 1951 1952 obj = alloc_buf->allocate(word_sz); 1953 assert(obj != NULL, "buffer was definitely big enough..."); 1954 } else { 1955 obj = _g1h->par_allocate_during_gc(purpose, word_sz); 1956 } 1957 return obj; 1958 } 1959 1960 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) { 1961 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz); 1962 if (obj != NULL) return obj; 1963 return allocate_slow(purpose, word_sz); 1964 } 1965 1966 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) { 1967 if (alloc_buffer(purpose)->contains(obj)) { 1968 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1), 1969 "should contain whole object"); 1970 alloc_buffer(purpose)->undo_allocation(obj, word_sz); 1971 } else { 1972 CollectedHeap::fill_with_object(obj, word_sz); 1973 add_to_undo_waste(word_sz); 1974 } 1975 } 1976 1977 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) { 1978 _evac_failure_cl = evac_failure_cl; 1979 } 1980 OopsInHeapRegionClosure* evac_failure_closure() { 1981 return _evac_failure_cl; 1982 } 1983 1984 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) { 1985 _evac_cl = evac_cl; 1986 } 1987 1988 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) { 1989 _partial_scan_cl = partial_scan_cl; 1990 } 1991 1992 int* hash_seed() { return &_hash_seed; } 1993 int queue_num() { return _queue_num; } 1994 1995 size_t term_attempts() const { return _term_attempts; } 1996 void note_term_attempt() { _term_attempts++; } 1997 1998 void start_strong_roots() { 1999 _start_strong_roots = os::elapsedTime(); 2000 } 2001 void end_strong_roots() { 2002 _strong_roots_time += (os::elapsedTime() - _start_strong_roots); 2003 } 2004 double strong_roots_time() const { return _strong_roots_time; } 2005 2006 void start_term_time() { 2007 note_term_attempt(); 2008 _start_term = os::elapsedTime(); 2009 } 2010 void end_term_time() { 2011 _term_time += (os::elapsedTime() - _start_term); 2012 } 2013 double term_time() const { return _term_time; } 2014 2015 double elapsed_time() const { 2016 return os::elapsedTime() - _start; 2017 } 2018 2019 static void 2020 print_termination_stats_hdr(outputStream* const st = gclog_or_tty); 2021 void 2022 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const; 2023 2024 size_t* surviving_young_words() { 2025 // We add on to hide entry 0 which accumulates surviving words for 2026 // age -1 regions (i.e. non-young ones) 2027 return _surviving_young_words; 2028 } 2029 2030 void retire_alloc_buffers() { 2031 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) { 2032 size_t waste = _alloc_buffers[ap]->words_remaining(); 2033 add_to_alloc_buffer_waste(waste); 2034 _alloc_buffers[ap]->retire(true, false); 2035 } 2036 } 2037 2038 template <class T> void deal_with_reference(T* ref_to_scan) { 2039 if (has_partial_array_mask(ref_to_scan)) { 2040 _partial_scan_cl->do_oop_nv(ref_to_scan); 2041 } else { 2042 // Note: we can use "raw" versions of "region_containing" because 2043 // "obj_to_scan" is definitely in the heap, and is not in a 2044 // humongous region. 2045 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan); 2046 _evac_cl->set_region(r); 2047 _evac_cl->do_oop_nv(ref_to_scan); 2048 } 2049 } 2050 2051 void deal_with_reference(StarTask ref) { 2052 assert(verify_task(ref), "sanity"); 2053 if (ref.is_narrow()) { 2054 deal_with_reference((narrowOop*)ref); 2055 } else { 2056 deal_with_reference((oop*)ref); 2057 } 2058 } 2059 2060 public: 2061 void trim_queue(); 2062 }; 2063 2064 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP