1 /* 2 * Copyright (c) 2001, 2013, 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/shared/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 GenerationSpec; 49 class OopsInHeapRegionClosure; 50 class G1KlassScanClosure; 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, mtGC> RefToScanQueue; 66 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> 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<mtGC> { 78 private: 79 G1CollectedHeap* _g1h; 80 81 HeapRegion* _head; 82 83 HeapRegion* _survivor_head; 84 HeapRegion* _survivor_tail; 85 86 HeapRegion* _curr; 87 88 uint _length; 89 uint _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 uint length() { return _length; } 105 uint 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 (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes; 115 } 116 size_t survivor_used_bytes() { 117 return (size_t) 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 // (optional) _is_alive_non_header closure in the STW 161 // reference processor. It is also extensively used during 162 // refence 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_G1CollectFull; 194 friend class VM_G1IncCollectionPause; 195 friend class VMStructs; 196 friend class MutatorAllocRegion; 197 friend class SurvivorGCAllocRegion; 198 friend class OldGCAllocRegion; 199 200 // Closures used in implementation. 201 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object> 202 friend class G1ParCopyClosure; 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. 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 old regions. 243 MasterOldRegionSet _old_set; 244 245 // It keeps track of the humongous regions. 246 MasterHumongousRegionSet _humongous_set; 247 248 // The number of regions we could create by expansion. 249 uint _expansion_regions; 250 251 // The block offset table for the G1 heap. 252 G1BlockOffsetSharedArray* _bot_shared; 253 254 // Tears down the region sets / lists so that they are empty and the 255 // regions on the heap do not belong to a region set / list. The 256 // only exception is the humongous set which we leave unaltered. If 257 // free_list_only is true, it will only tear down the master free 258 // list. It is called before a Full GC (free_list_only == false) or 259 // before heap shrinking (free_list_only == true). 260 void tear_down_region_sets(bool free_list_only); 261 262 // Rebuilds the region sets / lists so that they are repopulated to 263 // reflect the contents of the heap. The only exception is the 264 // humongous set which was not torn down in the first place. If 265 // free_list_only is true, it will only rebuild the master free 266 // list. It is called after a Full GC (free_list_only == false) or 267 // after heap shrinking (free_list_only == true). 268 void rebuild_region_sets(bool free_list_only); 269 270 // The sequence of all heap regions in the heap. 271 HeapRegionSeq _hrs; 272 273 // Alloc region used to satisfy mutator allocation requests. 274 MutatorAllocRegion _mutator_alloc_region; 275 276 // Alloc region used to satisfy allocation requests by the GC for 277 // survivor objects. 278 SurvivorGCAllocRegion _survivor_gc_alloc_region; 279 280 // PLAB sizing policy for survivors. 281 PLABStats _survivor_plab_stats; 282 283 // Alloc region used to satisfy allocation requests by the GC for 284 // old objects. 285 OldGCAllocRegion _old_gc_alloc_region; 286 287 // PLAB sizing policy for tenured objects. 288 PLABStats _old_plab_stats; 289 290 PLABStats* stats_for_purpose(GCAllocPurpose purpose) { 291 PLABStats* stats = NULL; 292 293 switch (purpose) { 294 case GCAllocForSurvived: 295 stats = &_survivor_plab_stats; 296 break; 297 case GCAllocForTenured: 298 stats = &_old_plab_stats; 299 break; 300 default: 301 assert(false, "unrecognized GCAllocPurpose"); 302 } 303 304 return stats; 305 } 306 307 // The last old region we allocated to during the last GC. 308 // Typically, it is not full so we should re-use it during the next GC. 309 HeapRegion* _retained_old_gc_alloc_region; 310 311 // It specifies whether we should attempt to expand the heap after a 312 // region allocation failure. If heap expansion fails we set this to 313 // false so that we don't re-attempt the heap expansion (it's likely 314 // that subsequent expansion attempts will also fail if one fails). 315 // Currently, it is only consulted during GC and it's reset at the 316 // start of each GC. 317 bool _expand_heap_after_alloc_failure; 318 319 // It resets the mutator alloc region before new allocations can take place. 320 void init_mutator_alloc_region(); 321 322 // It releases the mutator alloc region. 323 void release_mutator_alloc_region(); 324 325 // It initializes the GC alloc regions at the start of a GC. 326 void init_gc_alloc_regions(); 327 328 // It releases the GC alloc regions at the end of a GC. 329 void release_gc_alloc_regions(uint no_of_gc_workers); 330 331 // It does any cleanup that needs to be done on the GC alloc regions 332 // before a Full GC. 333 void abandon_gc_alloc_regions(); 334 335 // Helper for monitoring and management support. 336 G1MonitoringSupport* _g1mm; 337 338 // Determines PLAB size for a particular allocation purpose. 339 size_t desired_plab_sz(GCAllocPurpose purpose); 340 341 // Outside of GC pauses, the number of bytes used in all regions other 342 // than the current allocation region. 343 size_t _summary_bytes_used; 344 345 // This is used for a quick test on whether a reference points into 346 // the collection set or not. Basically, we have an array, with one 347 // byte per region, and that byte denotes whether the corresponding 348 // region is in the collection set or not. The entry corresponding 349 // the bottom of the heap, i.e., region 0, is pointed to by 350 // _in_cset_fast_test_base. The _in_cset_fast_test field has been 351 // biased so that it actually points to address 0 of the address 352 // space, to make the test as fast as possible (we can simply shift 353 // the address to address into it, instead of having to subtract the 354 // bottom of the heap from the address before shifting it; basically 355 // it works in the same way the card table works). 356 bool* _in_cset_fast_test; 357 358 // The allocated array used for the fast test on whether a reference 359 // points into the collection set or not. This field is also used to 360 // free the array. 361 bool* _in_cset_fast_test_base; 362 363 // The length of the _in_cset_fast_test_base array. 364 uint _in_cset_fast_test_length; 365 366 volatile unsigned _gc_time_stamp; 367 368 size_t* _surviving_young_words; 369 370 G1HRPrinter _hr_printer; 371 372 void setup_surviving_young_words(); 373 void update_surviving_young_words(size_t* surv_young_words); 374 void cleanup_surviving_young_words(); 375 376 // It decides whether an explicit GC should start a concurrent cycle 377 // instead of doing a STW GC. Currently, a concurrent cycle is 378 // explicitly started if: 379 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 380 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 381 // (c) cause == _g1_humongous_allocation 382 bool should_do_concurrent_full_gc(GCCause::Cause cause); 383 384 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 385 // concurrent cycles) we have started. 386 volatile unsigned int _old_marking_cycles_started; 387 388 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 389 // concurrent cycles) we have completed. 390 volatile unsigned int _old_marking_cycles_completed; 391 392 // This is a non-product method that is helpful for testing. It is 393 // called at the end of a GC and artificially expands the heap by 394 // allocating a number of dead regions. This way we can induce very 395 // frequent marking cycles and stress the cleanup / concurrent 396 // cleanup code more (as all the regions that will be allocated by 397 // this method will be found dead by the marking cycle). 398 void allocate_dummy_regions() PRODUCT_RETURN; 399 400 // Clear RSets after a compaction. It also resets the GC time stamps. 401 void clear_rsets_post_compaction(); 402 403 // If the HR printer is active, dump the state of the regions in the 404 // heap after a compaction. 405 void print_hrs_post_compaction(); 406 407 double verify(bool guard, const char* msg); 408 void verify_before_gc(); 409 void verify_after_gc(); 410 411 void log_gc_header(); 412 void log_gc_footer(double pause_time_sec); 413 414 // These are macros so that, if the assert fires, we get the correct 415 // line number, file, etc. 416 417 #define heap_locking_asserts_err_msg(_extra_message_) \ 418 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 419 (_extra_message_), \ 420 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 421 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 422 BOOL_TO_STR(Thread::current()->is_VM_thread())) 423 424 #define assert_heap_locked() \ 425 do { \ 426 assert(Heap_lock->owned_by_self(), \ 427 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \ 428 } while (0) 429 430 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 431 do { \ 432 assert(Heap_lock->owned_by_self() || \ 433 (SafepointSynchronize::is_at_safepoint() && \ 434 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 435 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \ 436 "should be at a safepoint")); \ 437 } while (0) 438 439 #define assert_heap_locked_and_not_at_safepoint() \ 440 do { \ 441 assert(Heap_lock->owned_by_self() && \ 442 !SafepointSynchronize::is_at_safepoint(), \ 443 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \ 444 "should not be at a safepoint")); \ 445 } while (0) 446 447 #define assert_heap_not_locked() \ 448 do { \ 449 assert(!Heap_lock->owned_by_self(), \ 450 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \ 451 } while (0) 452 453 #define assert_heap_not_locked_and_not_at_safepoint() \ 454 do { \ 455 assert(!Heap_lock->owned_by_self() && \ 456 !SafepointSynchronize::is_at_safepoint(), \ 457 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \ 458 "should not be at a safepoint")); \ 459 } while (0) 460 461 #define assert_at_safepoint(_should_be_vm_thread_) \ 462 do { \ 463 assert(SafepointSynchronize::is_at_safepoint() && \ 464 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 465 heap_locking_asserts_err_msg("should be at a safepoint")); \ 466 } while (0) 467 468 #define assert_not_at_safepoint() \ 469 do { \ 470 assert(!SafepointSynchronize::is_at_safepoint(), \ 471 heap_locking_asserts_err_msg("should not be at a safepoint")); \ 472 } while (0) 473 474 protected: 475 476 // The young region list. 477 YoungList* _young_list; 478 479 // The current policy object for the collector. 480 G1CollectorPolicy* _g1_policy; 481 482 // This is the second level of trying to allocate a new region. If 483 // new_region() didn't find a region on the free_list, this call will 484 // check whether there's anything available on the 485 // secondary_free_list and/or wait for more regions to appear on 486 // that list, if _free_regions_coming is set. 487 HeapRegion* new_region_try_secondary_free_list(); 488 489 // Try to allocate a single non-humongous HeapRegion sufficient for 490 // an allocation of the given word_size. If do_expand is true, 491 // attempt to expand the heap if necessary to satisfy the allocation 492 // request. 493 HeapRegion* new_region(size_t word_size, bool do_expand); 494 495 // Attempt to satisfy a humongous allocation request of the given 496 // size by finding a contiguous set of free regions of num_regions 497 // length and remove them from the master free list. Return the 498 // index of the first region or G1_NULL_HRS_INDEX if the search 499 // was unsuccessful. 500 uint humongous_obj_allocate_find_first(uint num_regions, 501 size_t word_size); 502 503 // Initialize a contiguous set of free regions of length num_regions 504 // and starting at index first so that they appear as a single 505 // humongous region. 506 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 507 uint num_regions, 508 size_t word_size); 509 510 // Attempt to allocate a humongous object of the given size. Return 511 // NULL if unsuccessful. 512 HeapWord* humongous_obj_allocate(size_t word_size); 513 514 // The following two methods, allocate_new_tlab() and 515 // mem_allocate(), are the two main entry points from the runtime 516 // into the G1's allocation routines. They have the following 517 // assumptions: 518 // 519 // * They should both be called outside safepoints. 520 // 521 // * They should both be called without holding the Heap_lock. 522 // 523 // * All allocation requests for new TLABs should go to 524 // allocate_new_tlab(). 525 // 526 // * All non-TLAB allocation requests should go to mem_allocate(). 527 // 528 // * If either call cannot satisfy the allocation request using the 529 // current allocating region, they will try to get a new one. If 530 // this fails, they will attempt to do an evacuation pause and 531 // retry the allocation. 532 // 533 // * If all allocation attempts fail, even after trying to schedule 534 // an evacuation pause, allocate_new_tlab() will return NULL, 535 // whereas mem_allocate() will attempt a heap expansion and/or 536 // schedule a Full GC. 537 // 538 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 539 // should never be called with word_size being humongous. All 540 // humongous allocation requests should go to mem_allocate() which 541 // will satisfy them with a special path. 542 543 virtual HeapWord* allocate_new_tlab(size_t word_size); 544 545 virtual HeapWord* mem_allocate(size_t word_size, 546 bool* gc_overhead_limit_was_exceeded); 547 548 // The following three methods take a gc_count_before_ret 549 // parameter which is used to return the GC count if the method 550 // returns NULL. Given that we are required to read the GC count 551 // while holding the Heap_lock, and these paths will take the 552 // Heap_lock at some point, it's easier to get them to read the GC 553 // count while holding the Heap_lock before they return NULL instead 554 // of the caller (namely: mem_allocate()) having to also take the 555 // Heap_lock just to read the GC count. 556 557 // First-level mutator allocation attempt: try to allocate out of 558 // the mutator alloc region without taking the Heap_lock. This 559 // should only be used for non-humongous allocations. 560 inline HeapWord* attempt_allocation(size_t word_size, 561 unsigned int* gc_count_before_ret); 562 563 // Second-level mutator allocation attempt: take the Heap_lock and 564 // retry the allocation attempt, potentially scheduling a GC 565 // pause. This should only be used for non-humongous allocations. 566 HeapWord* attempt_allocation_slow(size_t word_size, 567 unsigned int* gc_count_before_ret); 568 569 // Takes the Heap_lock and attempts a humongous allocation. It can 570 // potentially schedule a GC pause. 571 HeapWord* attempt_allocation_humongous(size_t word_size, 572 unsigned int* gc_count_before_ret); 573 574 // Allocation attempt that should be called during safepoints (e.g., 575 // at the end of a successful GC). expect_null_mutator_alloc_region 576 // specifies whether the mutator alloc region is expected to be NULL 577 // or not. 578 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 579 bool expect_null_mutator_alloc_region); 580 581 // It dirties the cards that cover the block so that so that the post 582 // write barrier never queues anything when updating objects on this 583 // block. It is assumed (and in fact we assert) that the block 584 // belongs to a young region. 585 inline void dirty_young_block(HeapWord* start, size_t word_size); 586 587 // Allocate blocks during garbage collection. Will ensure an 588 // allocation region, either by picking one or expanding the 589 // heap, and then allocate a block of the given size. The block 590 // may not be a humongous - it must fit into a single heap region. 591 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size); 592 593 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose, 594 HeapRegion* alloc_region, 595 bool par, 596 size_t word_size); 597 598 // Ensure that no further allocations can happen in "r", bearing in mind 599 // that parallel threads might be attempting allocations. 600 void par_allocate_remaining_space(HeapRegion* r); 601 602 // Allocation attempt during GC for a survivor object / PLAB. 603 inline HeapWord* survivor_attempt_allocation(size_t word_size); 604 605 // Allocation attempt during GC for an old object / PLAB. 606 inline HeapWord* old_attempt_allocation(size_t word_size); 607 608 // These methods are the "callbacks" from the G1AllocRegion class. 609 610 // For mutator alloc regions. 611 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 612 void retire_mutator_alloc_region(HeapRegion* alloc_region, 613 size_t allocated_bytes); 614 615 // For GC alloc regions. 616 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 617 GCAllocPurpose ap); 618 void retire_gc_alloc_region(HeapRegion* alloc_region, 619 size_t allocated_bytes, GCAllocPurpose ap); 620 621 // - if explicit_gc is true, the GC is for a System.gc() or a heap 622 // inspection request and should collect the entire heap 623 // - if clear_all_soft_refs is true, all soft references should be 624 // cleared during the GC 625 // - if explicit_gc is false, word_size describes the allocation that 626 // the GC should attempt (at least) to satisfy 627 // - it returns false if it is unable to do the collection due to the 628 // GC locker being active, true otherwise 629 bool do_collection(bool explicit_gc, 630 bool clear_all_soft_refs, 631 size_t word_size); 632 633 // Callback from VM_G1CollectFull operation. 634 // Perform a full collection. 635 virtual void do_full_collection(bool clear_all_soft_refs); 636 637 // Resize the heap if necessary after a full collection. If this is 638 // after a collect-for allocation, "word_size" is the allocation size, 639 // and will be considered part of the used portion of the heap. 640 void resize_if_necessary_after_full_collection(size_t word_size); 641 642 // Callback from VM_G1CollectForAllocation operation. 643 // This function does everything necessary/possible to satisfy a 644 // failed allocation request (including collection, expansion, etc.) 645 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded); 646 647 // Attempting to expand the heap sufficiently 648 // to support an allocation of the given "word_size". If 649 // successful, perform the allocation and return the address of the 650 // allocated block, or else "NULL". 651 HeapWord* expand_and_allocate(size_t word_size); 652 653 // Process any reference objects discovered during 654 // an incremental evacuation pause. 655 void process_discovered_references(uint no_of_gc_workers); 656 657 // Enqueue any remaining discovered references 658 // after processing. 659 void enqueue_discovered_references(uint no_of_gc_workers); 660 661 public: 662 663 G1MonitoringSupport* g1mm() { 664 assert(_g1mm != NULL, "should have been initialized"); 665 return _g1mm; 666 } 667 668 // Expand the garbage-first heap by at least the given size (in bytes!). 669 // Returns true if the heap was expanded by the requested amount; 670 // false otherwise. 671 // (Rounds up to a HeapRegion boundary.) 672 bool expand(size_t expand_bytes); 673 674 // Do anything common to GC's. 675 virtual void gc_prologue(bool full); 676 virtual void gc_epilogue(bool full); 677 678 // We register a region with the fast "in collection set" test. We 679 // simply set to true the array slot corresponding to this region. 680 void register_region_with_in_cset_fast_test(HeapRegion* r) { 681 assert(_in_cset_fast_test_base != NULL, "sanity"); 682 assert(r->in_collection_set(), "invariant"); 683 uint index = r->hrs_index(); 684 assert(index < _in_cset_fast_test_length, "invariant"); 685 assert(!_in_cset_fast_test_base[index], "invariant"); 686 _in_cset_fast_test_base[index] = true; 687 } 688 689 // This is a fast test on whether a reference points into the 690 // collection set or not. It does not assume that the reference 691 // points into the heap; if it doesn't, it will return false. 692 bool in_cset_fast_test(oop obj) { 693 assert(_in_cset_fast_test != NULL, "sanity"); 694 if (_g1_committed.contains((HeapWord*) obj)) { 695 // no need to subtract the bottom of the heap from obj, 696 // _in_cset_fast_test is biased 697 uintx index = (uintx) obj >> HeapRegion::LogOfHRGrainBytes; 698 bool ret = _in_cset_fast_test[index]; 699 // let's make sure the result is consistent with what the slower 700 // test returns 701 assert( ret || !obj_in_cs(obj), "sanity"); 702 assert(!ret || obj_in_cs(obj), "sanity"); 703 return ret; 704 } else { 705 return false; 706 } 707 } 708 709 void clear_cset_fast_test() { 710 assert(_in_cset_fast_test_base != NULL, "sanity"); 711 memset(_in_cset_fast_test_base, false, 712 (size_t) _in_cset_fast_test_length * sizeof(bool)); 713 } 714 715 // This is called at the start of either a concurrent cycle or a Full 716 // GC to update the number of old marking cycles started. 717 void increment_old_marking_cycles_started(); 718 719 // This is called at the end of either a concurrent cycle or a Full 720 // GC to update the number of old marking cycles completed. Those two 721 // can happen in a nested fashion, i.e., we start a concurrent 722 // cycle, a Full GC happens half-way through it which ends first, 723 // and then the cycle notices that a Full GC happened and ends 724 // too. The concurrent parameter is a boolean to help us do a bit 725 // tighter consistency checking in the method. If concurrent is 726 // false, the caller is the inner caller in the nesting (i.e., the 727 // Full GC). If concurrent is true, the caller is the outer caller 728 // in this nesting (i.e., the concurrent cycle). Further nesting is 729 // not currently supported. The end of this call also notifies 730 // the FullGCCount_lock in case a Java thread is waiting for a full 731 // GC to happen (e.g., it called System.gc() with 732 // +ExplicitGCInvokesConcurrent). 733 void increment_old_marking_cycles_completed(bool concurrent); 734 735 unsigned int old_marking_cycles_completed() { 736 return _old_marking_cycles_completed; 737 } 738 739 G1HRPrinter* hr_printer() { return &_hr_printer; } 740 741 protected: 742 743 // Shrink the garbage-first heap by at most the given size (in bytes!). 744 // (Rounds down to a HeapRegion boundary.) 745 virtual void shrink(size_t expand_bytes); 746 void shrink_helper(size_t expand_bytes); 747 748 #if TASKQUEUE_STATS 749 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 750 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 751 void reset_taskqueue_stats(); 752 #endif // TASKQUEUE_STATS 753 754 // Schedule the VM operation that will do an evacuation pause to 755 // satisfy an allocation request of word_size. *succeeded will 756 // return whether the VM operation was successful (it did do an 757 // evacuation pause) or not (another thread beat us to it or the GC 758 // locker was active). Given that we should not be holding the 759 // Heap_lock when we enter this method, we will pass the 760 // gc_count_before (i.e., total_collections()) as a parameter since 761 // it has to be read while holding the Heap_lock. Currently, both 762 // methods that call do_collection_pause() release the Heap_lock 763 // before the call, so it's easy to read gc_count_before just before. 764 HeapWord* do_collection_pause(size_t word_size, 765 unsigned int gc_count_before, 766 bool* succeeded); 767 768 // The guts of the incremental collection pause, executed by the vm 769 // thread. It returns false if it is unable to do the collection due 770 // to the GC locker being active, true otherwise 771 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 772 773 // Actually do the work of evacuating the collection set. 774 void evacuate_collection_set(); 775 776 // The g1 remembered set of the heap. 777 G1RemSet* _g1_rem_set; 778 // And it's mod ref barrier set, used to track updates for the above. 779 ModRefBarrierSet* _mr_bs; 780 781 // A set of cards that cover the objects for which the Rsets should be updated 782 // concurrently after the collection. 783 DirtyCardQueueSet _dirty_card_queue_set; 784 785 // The Heap Region Rem Set Iterator. 786 HeapRegionRemSetIterator** _rem_set_iterator; 787 788 // The closure used to refine a single card. 789 RefineCardTableEntryClosure* _refine_cte_cl; 790 791 // A function to check the consistency of dirty card logs. 792 void check_ct_logs_at_safepoint(); 793 794 // A DirtyCardQueueSet that is used to hold cards that contain 795 // references into the current collection set. This is used to 796 // update the remembered sets of the regions in the collection 797 // set in the event of an evacuation failure. 798 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 799 800 // After a collection pause, make the regions in the CS into free 801 // regions. 802 void free_collection_set(HeapRegion* cs_head); 803 804 // Abandon the current collection set without recording policy 805 // statistics or updating free lists. 806 void abandon_collection_set(HeapRegion* cs_head); 807 808 // Applies "scan_non_heap_roots" to roots outside the heap, 809 // "scan_rs" to roots inside the heap (having done "set_region" to 810 // indicate the region in which the root resides), 811 // and does "scan_metadata" If "scan_rs" is 812 // NULL, then this step is skipped. The "worker_i" 813 // param is for use with parallel roots processing, and should be 814 // the "i" of the calling parallel worker thread's work(i) function. 815 // In the sequential case this param will be ignored. 816 void g1_process_strong_roots(bool is_scavenging, 817 ScanningOption so, 818 OopClosure* scan_non_heap_roots, 819 OopsInHeapRegionClosure* scan_rs, 820 G1KlassScanClosure* scan_klasses, 821 int worker_i); 822 823 // Apply "blk" to all the weak roots of the system. These include 824 // JNI weak roots, the code cache, system dictionary, symbol table, 825 // string table, and referents of reachable weak refs. 826 void g1_process_weak_roots(OopClosure* root_closure, 827 OopClosure* non_root_closure); 828 829 // Frees a non-humongous region by initializing its contents and 830 // adding it to the free list that's passed as a parameter (this is 831 // usually a local list which will be appended to the master free 832 // list later). The used bytes of freed regions are accumulated in 833 // pre_used. If par is true, the region's RSet will not be freed 834 // up. The assumption is that this will be done later. 835 void free_region(HeapRegion* hr, 836 size_t* pre_used, 837 FreeRegionList* free_list, 838 bool par); 839 840 // Frees a humongous region by collapsing it into individual regions 841 // and calling free_region() for each of them. The freed regions 842 // will be added to the free list that's passed as a parameter (this 843 // is usually a local list which will be appended to the master free 844 // list later). The used bytes of freed regions are accumulated in 845 // pre_used. If par is true, the region's RSet will not be freed 846 // up. The assumption is that this will be done later. 847 void free_humongous_region(HeapRegion* hr, 848 size_t* pre_used, 849 FreeRegionList* free_list, 850 HumongousRegionSet* humongous_proxy_set, 851 bool par); 852 853 // Notifies all the necessary spaces that the committed space has 854 // been updated (either expanded or shrunk). It should be called 855 // after _g1_storage is updated. 856 void update_committed_space(HeapWord* old_end, HeapWord* new_end); 857 858 // The concurrent marker (and the thread it runs in.) 859 ConcurrentMark* _cm; 860 ConcurrentMarkThread* _cmThread; 861 bool _mark_in_progress; 862 863 // The concurrent refiner. 864 ConcurrentG1Refine* _cg1r; 865 866 // The parallel task queues 867 RefToScanQueueSet *_task_queues; 868 869 // True iff a evacuation has failed in the current collection. 870 bool _evacuation_failed; 871 872 // Set the attribute indicating whether evacuation has failed in the 873 // current collection. 874 void set_evacuation_failed(bool b) { _evacuation_failed = b; } 875 876 // Failed evacuations cause some logical from-space objects to have 877 // forwarding pointers to themselves. Reset them. 878 void remove_self_forwarding_pointers(); 879 880 // When one is non-null, so is the other. Together, they each pair is 881 // an object with a preserved mark, and its mark value. 882 GrowableArray<oop>* _objs_with_preserved_marks; 883 GrowableArray<markOop>* _preserved_marks_of_objs; 884 885 // Preserve the mark of "obj", if necessary, in preparation for its mark 886 // word being overwritten with a self-forwarding-pointer. 887 void preserve_mark_if_necessary(oop obj, markOop m); 888 889 // The stack of evac-failure objects left to be scanned. 890 GrowableArray<oop>* _evac_failure_scan_stack; 891 // The closure to apply to evac-failure objects. 892 893 OopsInHeapRegionClosure* _evac_failure_closure; 894 // Set the field above. 895 void 896 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) { 897 _evac_failure_closure = evac_failure_closure; 898 } 899 900 // Push "obj" on the scan stack. 901 void push_on_evac_failure_scan_stack(oop obj); 902 // Process scan stack entries until the stack is empty. 903 void drain_evac_failure_scan_stack(); 904 // True iff an invocation of "drain_scan_stack" is in progress; to 905 // prevent unnecessary recursion. 906 bool _drain_in_progress; 907 908 // Do any necessary initialization for evacuation-failure handling. 909 // "cl" is the closure that will be used to process evac-failure 910 // objects. 911 void init_for_evac_failure(OopsInHeapRegionClosure* cl); 912 // Do any necessary cleanup for evacuation-failure handling data 913 // structures. 914 void finalize_for_evac_failure(); 915 916 // An attempt to evacuate "obj" has failed; take necessary steps. 917 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj); 918 void handle_evacuation_failure_common(oop obj, markOop m); 919 920 #ifndef PRODUCT 921 // Support for forcing evacuation failures. Analogous to 922 // PromotionFailureALot for the other collectors. 923 924 // Records whether G1EvacuationFailureALot should be in effect 925 // for the current GC 926 bool _evacuation_failure_alot_for_current_gc; 927 928 // Used to record the GC number for interval checking when 929 // determining whether G1EvaucationFailureALot is in effect 930 // for the current GC. 931 size_t _evacuation_failure_alot_gc_number; 932 933 // Count of the number of evacuations between failures. 934 volatile size_t _evacuation_failure_alot_count; 935 936 // Set whether G1EvacuationFailureALot should be in effect 937 // for the current GC (based upon the type of GC and which 938 // command line flags are set); 939 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 940 bool during_initial_mark, 941 bool during_marking); 942 943 inline void set_evacuation_failure_alot_for_current_gc(); 944 945 // Return true if it's time to cause an evacuation failure. 946 inline bool evacuation_should_fail(); 947 948 // Reset the G1EvacuationFailureALot counters. Should be called at 949 // the end of an evacuation pause in which an evacuation failure ocurred. 950 inline void reset_evacuation_should_fail(); 951 #endif // !PRODUCT 952 953 // ("Weak") Reference processing support. 954 // 955 // G1 has 2 instances of the referece processor class. One 956 // (_ref_processor_cm) handles reference object discovery 957 // and subsequent processing during concurrent marking cycles. 958 // 959 // The other (_ref_processor_stw) handles reference object 960 // discovery and processing during full GCs and incremental 961 // evacuation pauses. 962 // 963 // During an incremental pause, reference discovery will be 964 // temporarily disabled for _ref_processor_cm and will be 965 // enabled for _ref_processor_stw. At the end of the evacuation 966 // pause references discovered by _ref_processor_stw will be 967 // processed and discovery will be disabled. The previous 968 // setting for reference object discovery for _ref_processor_cm 969 // will be re-instated. 970 // 971 // At the start of marking: 972 // * Discovery by the CM ref processor is verified to be inactive 973 // and it's discovered lists are empty. 974 // * Discovery by the CM ref processor is then enabled. 975 // 976 // At the end of marking: 977 // * Any references on the CM ref processor's discovered 978 // lists are processed (possibly MT). 979 // 980 // At the start of full GC we: 981 // * Disable discovery by the CM ref processor and 982 // empty CM ref processor's discovered lists 983 // (without processing any entries). 984 // * Verify that the STW ref processor is inactive and it's 985 // discovered lists are empty. 986 // * Temporarily set STW ref processor discovery as single threaded. 987 // * Temporarily clear the STW ref processor's _is_alive_non_header 988 // field. 989 // * Finally enable discovery by the STW ref processor. 990 // 991 // The STW ref processor is used to record any discovered 992 // references during the full GC. 993 // 994 // At the end of a full GC we: 995 // * Enqueue any reference objects discovered by the STW ref processor 996 // that have non-live referents. This has the side-effect of 997 // making the STW ref processor inactive by disabling discovery. 998 // * Verify that the CM ref processor is still inactive 999 // and no references have been placed on it's discovered 1000 // lists (also checked as a precondition during initial marking). 1001 1002 // The (stw) reference processor... 1003 ReferenceProcessor* _ref_processor_stw; 1004 1005 // During reference object discovery, the _is_alive_non_header 1006 // closure (if non-null) is applied to the referent object to 1007 // determine whether the referent is live. If so then the 1008 // reference object does not need to be 'discovered' and can 1009 // be treated as a regular oop. This has the benefit of reducing 1010 // the number of 'discovered' reference objects that need to 1011 // be processed. 1012 // 1013 // Instance of the is_alive closure for embedding into the 1014 // STW reference processor as the _is_alive_non_header field. 1015 // Supplying a value for the _is_alive_non_header field is 1016 // optional but doing so prevents unnecessary additions to 1017 // the discovered lists during reference discovery. 1018 G1STWIsAliveClosure _is_alive_closure_stw; 1019 1020 // The (concurrent marking) reference processor... 1021 ReferenceProcessor* _ref_processor_cm; 1022 1023 // Instance of the concurrent mark is_alive closure for embedding 1024 // into the Concurrent Marking reference processor as the 1025 // _is_alive_non_header field. Supplying a value for the 1026 // _is_alive_non_header field is optional but doing so prevents 1027 // unnecessary additions to the discovered lists during reference 1028 // discovery. 1029 G1CMIsAliveClosure _is_alive_closure_cm; 1030 1031 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 1032 HeapRegion** _worker_cset_start_region; 1033 1034 // Time stamp to validate the regions recorded in the cache 1035 // used by G1CollectedHeap::start_cset_region_for_worker(). 1036 // The heap region entry for a given worker is valid iff 1037 // the associated time stamp value matches the current value 1038 // of G1CollectedHeap::_gc_time_stamp. 1039 unsigned int* _worker_cset_start_region_time_stamp; 1040 1041 enum G1H_process_strong_roots_tasks { 1042 G1H_PS_filter_satb_buffers, 1043 G1H_PS_refProcessor_oops_do, 1044 // Leave this one last. 1045 G1H_PS_NumElements 1046 }; 1047 1048 SubTasksDone* _process_strong_tasks; 1049 1050 volatile bool _free_regions_coming; 1051 1052 public: 1053 1054 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; } 1055 1056 void set_refine_cte_cl_concurrency(bool concurrent); 1057 1058 RefToScanQueue *task_queue(int i) const; 1059 1060 // A set of cards where updates happened during the GC 1061 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 1062 1063 // A DirtyCardQueueSet that is used to hold cards that contain 1064 // references into the current collection set. This is used to 1065 // update the remembered sets of the regions in the collection 1066 // set in the event of an evacuation failure. 1067 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 1068 { return _into_cset_dirty_card_queue_set; } 1069 1070 // Create a G1CollectedHeap with the specified policy. 1071 // Must call the initialize method afterwards. 1072 // May not return if something goes wrong. 1073 G1CollectedHeap(G1CollectorPolicy* policy); 1074 1075 // Initialize the G1CollectedHeap to have the initial and 1076 // maximum sizes and remembered and barrier sets 1077 // specified by the policy object. 1078 jint initialize(); 1079 1080 // Initialize weak reference processing. 1081 virtual void ref_processing_init(); 1082 1083 void set_par_threads(uint t) { 1084 SharedHeap::set_par_threads(t); 1085 // Done in SharedHeap but oddly there are 1086 // two _process_strong_tasks's in a G1CollectedHeap 1087 // so do it here too. 1088 _process_strong_tasks->set_n_threads(t); 1089 } 1090 1091 // Set _n_par_threads according to a policy TBD. 1092 void set_par_threads(); 1093 1094 void set_n_termination(int t) { 1095 _process_strong_tasks->set_n_threads(t); 1096 } 1097 1098 virtual CollectedHeap::Name kind() const { 1099 return CollectedHeap::G1CollectedHeap; 1100 } 1101 1102 // The current policy object for the collector. 1103 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1104 1105 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } 1106 1107 // Adaptive size policy. No such thing for g1. 1108 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1109 1110 // The rem set and barrier set. 1111 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1112 ModRefBarrierSet* mr_bs() const { return _mr_bs; } 1113 1114 // The rem set iterator. 1115 HeapRegionRemSetIterator* rem_set_iterator(int i) { 1116 return _rem_set_iterator[i]; 1117 } 1118 1119 HeapRegionRemSetIterator* rem_set_iterator() { 1120 return _rem_set_iterator[0]; 1121 } 1122 1123 unsigned get_gc_time_stamp() { 1124 return _gc_time_stamp; 1125 } 1126 1127 void reset_gc_time_stamp() { 1128 _gc_time_stamp = 0; 1129 OrderAccess::fence(); 1130 // Clear the cached CSet starting regions and time stamps. 1131 // Their validity is dependent on the GC timestamp. 1132 clear_cset_start_regions(); 1133 } 1134 1135 void check_gc_time_stamps() PRODUCT_RETURN; 1136 1137 void increment_gc_time_stamp() { 1138 ++_gc_time_stamp; 1139 OrderAccess::fence(); 1140 } 1141 1142 // Reset the given region's GC timestamp. If it's starts humongous, 1143 // also reset the GC timestamp of its corresponding 1144 // continues humongous regions too. 1145 void reset_gc_time_stamps(HeapRegion* hr); 1146 1147 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1148 DirtyCardQueue* into_cset_dcq, 1149 bool concurrent, int worker_i); 1150 1151 // The shared block offset table array. 1152 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1153 1154 // Reference Processing accessors 1155 1156 // The STW reference processor.... 1157 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1158 1159 // The Concurent Marking reference processor... 1160 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1161 1162 virtual size_t capacity() const; 1163 virtual size_t used() const; 1164 // This should be called when we're not holding the heap lock. The 1165 // result might be a bit inaccurate. 1166 size_t used_unlocked() const; 1167 size_t recalculate_used() const; 1168 1169 // These virtual functions do the actual allocation. 1170 // Some heaps may offer a contiguous region for shared non-blocking 1171 // allocation, via inlined code (by exporting the address of the top and 1172 // end fields defining the extent of the contiguous allocation region.) 1173 // But G1CollectedHeap doesn't yet support this. 1174 1175 // Return an estimate of the maximum allocation that could be performed 1176 // without triggering any collection or expansion activity. In a 1177 // generational collector, for example, this is probably the largest 1178 // allocation that could be supported (without expansion) in the youngest 1179 // generation. It is "unsafe" because no locks are taken; the result 1180 // should be treated as an approximation, not a guarantee, for use in 1181 // heuristic resizing decisions. 1182 virtual size_t unsafe_max_alloc(); 1183 1184 virtual bool is_maximal_no_gc() const { 1185 return _g1_storage.uncommitted_size() == 0; 1186 } 1187 1188 // The total number of regions in the heap. 1189 uint n_regions() { return _hrs.length(); } 1190 1191 // The max number of regions in the heap. 1192 uint max_regions() { return _hrs.max_length(); } 1193 1194 // The number of regions that are completely free. 1195 uint free_regions() { return _free_list.length(); } 1196 1197 // The number of regions that are not completely free. 1198 uint used_regions() { return n_regions() - free_regions(); } 1199 1200 // The number of regions available for "regular" expansion. 1201 uint expansion_regions() { return _expansion_regions; } 1202 1203 // Factory method for HeapRegion instances. It will return NULL if 1204 // the allocation fails. 1205 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom); 1206 1207 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1208 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1209 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1210 void verify_dirty_young_regions() PRODUCT_RETURN; 1211 1212 #ifndef PRODUCT 1213 // Make sure that the given bitmap has no marked objects in the 1214 // range [from,limit). If it does, print an error message and return 1215 // false. Otherwise, just return true. bitmap_name should be "prev" 1216 // or "next". 1217 bool verify_bitmap(const char* bitmap_name, CMBitMapRO* bitmap, 1218 HeapWord* from, HeapWord* limit); 1219 1220 // Verify that the prev / next bitmap range [tams,end) for the given 1221 // region has no marks. Return true if all is well, false if errors 1222 // are detected. 1223 bool verify_bitmaps(const char* caller, HeapRegion* hr); 1224 #endif // PRODUCT 1225 1226 // If G1VerifyBitmaps is set, verify that the marking bitmaps for 1227 // the given region do not have any spurious marks. If errors are 1228 // detected, print appropriate error messages and crash. 1229 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN; 1230 1231 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not 1232 // have any spurious marks. If errors are detected, print 1233 // appropriate error messages and crash. 1234 void check_bitmaps(const char* caller) PRODUCT_RETURN; 1235 1236 // verify_region_sets() performs verification over the region 1237 // lists. It will be compiled in the product code to be used when 1238 // necessary (i.e., during heap verification). 1239 void verify_region_sets(); 1240 1241 // verify_region_sets_optional() is planted in the code for 1242 // list verification in non-product builds (and it can be enabled in 1243 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1). 1244 #if HEAP_REGION_SET_FORCE_VERIFY 1245 void verify_region_sets_optional() { 1246 verify_region_sets(); 1247 } 1248 #else // HEAP_REGION_SET_FORCE_VERIFY 1249 void verify_region_sets_optional() { } 1250 #endif // HEAP_REGION_SET_FORCE_VERIFY 1251 1252 #ifdef ASSERT 1253 bool is_on_master_free_list(HeapRegion* hr) { 1254 return hr->containing_set() == &_free_list; 1255 } 1256 1257 bool is_in_humongous_set(HeapRegion* hr) { 1258 return hr->containing_set() == &_humongous_set; 1259 } 1260 #endif // ASSERT 1261 1262 // Wrapper for the region list operations that can be called from 1263 // methods outside this class. 1264 1265 void secondary_free_list_add_as_tail(FreeRegionList* list) { 1266 _secondary_free_list.add_as_tail(list); 1267 } 1268 1269 void append_secondary_free_list() { 1270 _free_list.add_as_head(&_secondary_free_list); 1271 } 1272 1273 void append_secondary_free_list_if_not_empty_with_lock() { 1274 // If the secondary free list looks empty there's no reason to 1275 // take the lock and then try to append it. 1276 if (!_secondary_free_list.is_empty()) { 1277 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1278 append_secondary_free_list(); 1279 } 1280 } 1281 1282 void old_set_remove(HeapRegion* hr) { 1283 _old_set.remove(hr); 1284 } 1285 1286 size_t non_young_capacity_bytes() { 1287 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1288 } 1289 1290 void set_free_regions_coming(); 1291 void reset_free_regions_coming(); 1292 bool free_regions_coming() { return _free_regions_coming; } 1293 void wait_while_free_regions_coming(); 1294 1295 // Determine whether the given region is one that we are using as an 1296 // old GC alloc region. 1297 bool is_old_gc_alloc_region(HeapRegion* hr) { 1298 return hr == _retained_old_gc_alloc_region; 1299 } 1300 1301 // Perform a collection of the heap; intended for use in implementing 1302 // "System.gc". This probably implies as full a collection as the 1303 // "CollectedHeap" supports. 1304 virtual void collect(GCCause::Cause cause); 1305 1306 // The same as above but assume that the caller holds the Heap_lock. 1307 void collect_locked(GCCause::Cause cause); 1308 1309 // True iff a evacuation has failed in the most-recent collection. 1310 bool evacuation_failed() { return _evacuation_failed; } 1311 1312 // It will free a region if it has allocated objects in it that are 1313 // all dead. It calls either free_region() or 1314 // free_humongous_region() depending on the type of the region that 1315 // is passed to it. 1316 void free_region_if_empty(HeapRegion* hr, 1317 size_t* pre_used, 1318 FreeRegionList* free_list, 1319 OldRegionSet* old_proxy_set, 1320 HumongousRegionSet* humongous_proxy_set, 1321 HRRSCleanupTask* hrrs_cleanup_task, 1322 bool par); 1323 1324 // It appends the free list to the master free list and updates the 1325 // master humongous list according to the contents of the proxy 1326 // list. It also adjusts the total used bytes according to pre_used 1327 // (if par is true, it will do so by taking the ParGCRareEvent_lock). 1328 void update_sets_after_freeing_regions(size_t pre_used, 1329 FreeRegionList* free_list, 1330 OldRegionSet* old_proxy_set, 1331 HumongousRegionSet* humongous_proxy_set, 1332 bool par); 1333 1334 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1335 virtual bool is_in(const void* p) const; 1336 1337 // Return "TRUE" iff the given object address is within the collection 1338 // set. 1339 inline bool obj_in_cs(oop obj); 1340 1341 // Return "TRUE" iff the given object address is in the reserved 1342 // region of g1. 1343 bool is_in_g1_reserved(const void* p) const { 1344 return _g1_reserved.contains(p); 1345 } 1346 1347 // Returns a MemRegion that corresponds to the space that has been 1348 // reserved for the heap 1349 MemRegion g1_reserved() { 1350 return _g1_reserved; 1351 } 1352 1353 // Returns a MemRegion that corresponds to the space that has been 1354 // committed in the heap 1355 MemRegion g1_committed() { 1356 return _g1_committed; 1357 } 1358 1359 virtual bool is_in_closed_subset(const void* p) const; 1360 1361 // This resets the card table to all zeros. It is used after 1362 // a collection pause which used the card table to claim cards. 1363 void cleanUpCardTable(); 1364 1365 // Iteration functions. 1366 1367 // Iterate over all the ref-containing fields of all objects, calling 1368 // "cl.do_oop" on each. 1369 virtual void oop_iterate(ExtendedOopClosure* cl); 1370 1371 // Same as above, restricted to a memory region. 1372 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl); 1373 1374 // Iterate over all objects, calling "cl.do_object" on each. 1375 virtual void object_iterate(ObjectClosure* cl); 1376 1377 virtual void safe_object_iterate(ObjectClosure* cl) { 1378 object_iterate(cl); 1379 } 1380 1381 // Iterate over all objects allocated since the last collection, calling 1382 // "cl.do_object" on each. The heap must have been initialized properly 1383 // to support this function, or else this call will fail. 1384 virtual void object_iterate_since_last_GC(ObjectClosure* cl); 1385 1386 // Iterate over all spaces in use in the heap, in ascending address order. 1387 virtual void space_iterate(SpaceClosure* cl); 1388 1389 // Iterate over heap regions, in address order, terminating the 1390 // iteration early if the "doHeapRegion" method returns "true". 1391 void heap_region_iterate(HeapRegionClosure* blk) const; 1392 1393 // Return the region with the given index. It assumes the index is valid. 1394 HeapRegion* region_at(uint index) const { return _hrs.at(index); } 1395 1396 // Divide the heap region sequence into "chunks" of some size (the number 1397 // of regions divided by the number of parallel threads times some 1398 // overpartition factor, currently 4). Assumes that this will be called 1399 // in parallel by ParallelGCThreads worker threads with discinct worker 1400 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel 1401 // calls will use the same "claim_value", and that that claim value is 1402 // different from the claim_value of any heap region before the start of 1403 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by 1404 // attempting to claim the first region in each chunk, and, if 1405 // successful, applying the closure to each region in the chunk (and 1406 // setting the claim value of the second and subsequent regions of the 1407 // chunk.) For now requires that "doHeapRegion" always returns "false", 1408 // i.e., that a closure never attempt to abort a traversal. 1409 void heap_region_par_iterate_chunked(HeapRegionClosure* blk, 1410 uint worker, 1411 uint no_of_par_workers, 1412 jint claim_value); 1413 1414 // It resets all the region claim values to the default. 1415 void reset_heap_region_claim_values(); 1416 1417 // Resets the claim values of regions in the current 1418 // collection set to the default. 1419 void reset_cset_heap_region_claim_values(); 1420 1421 #ifdef ASSERT 1422 bool check_heap_region_claim_values(jint claim_value); 1423 1424 // Same as the routine above but only checks regions in the 1425 // current collection set. 1426 bool check_cset_heap_region_claim_values(jint claim_value); 1427 #endif // ASSERT 1428 1429 // Clear the cached cset start regions and (more importantly) 1430 // the time stamps. Called when we reset the GC time stamp. 1431 void clear_cset_start_regions(); 1432 1433 // Given the id of a worker, obtain or calculate a suitable 1434 // starting region for iterating over the current collection set. 1435 HeapRegion* start_cset_region_for_worker(int worker_i); 1436 1437 // This is a convenience method that is used by the 1438 // HeapRegionIterator classes to calculate the starting region for 1439 // each worker so that they do not all start from the same region. 1440 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers); 1441 1442 // Iterate over the regions (if any) in the current collection set. 1443 void collection_set_iterate(HeapRegionClosure* blk); 1444 1445 // As above but starting from region r 1446 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1447 1448 // Returns the first (lowest address) compactible space in the heap. 1449 virtual CompactibleSpace* first_compactible_space(); 1450 1451 // A CollectedHeap will contain some number of spaces. This finds the 1452 // space containing a given address, or else returns NULL. 1453 virtual Space* space_containing(const void* addr) const; 1454 1455 // A G1CollectedHeap will contain some number of heap regions. This 1456 // finds the region containing a given address, or else returns NULL. 1457 template <class T> 1458 inline HeapRegion* heap_region_containing(const T addr) const; 1459 1460 // Like the above, but requires "addr" to be in the heap (to avoid a 1461 // null-check), and unlike the above, may return an continuing humongous 1462 // region. 1463 template <class T> 1464 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1465 1466 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1467 // each address in the (reserved) heap is a member of exactly 1468 // one block. The defining characteristic of a block is that it is 1469 // possible to find its size, and thus to progress forward to the next 1470 // block. (Blocks may be of different sizes.) Thus, blocks may 1471 // represent Java objects, or they might be free blocks in a 1472 // free-list-based heap (or subheap), as long as the two kinds are 1473 // distinguishable and the size of each is determinable. 1474 1475 // Returns the address of the start of the "block" that contains the 1476 // address "addr". We say "blocks" instead of "object" since some heaps 1477 // may not pack objects densely; a chunk may either be an object or a 1478 // non-object. 1479 virtual HeapWord* block_start(const void* addr) const; 1480 1481 // Requires "addr" to be the start of a chunk, and returns its size. 1482 // "addr + size" is required to be the start of a new chunk, or the end 1483 // of the active area of the heap. 1484 virtual size_t block_size(const HeapWord* addr) const; 1485 1486 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1487 // the block is an object. 1488 virtual bool block_is_obj(const HeapWord* addr) const; 1489 1490 // Does this heap support heap inspection? (+PrintClassHistogram) 1491 virtual bool supports_heap_inspection() const { return true; } 1492 1493 // Section on thread-local allocation buffers (TLABs) 1494 // See CollectedHeap for semantics. 1495 1496 virtual bool supports_tlab_allocation() const; 1497 virtual size_t tlab_capacity(Thread* thr) const; 1498 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const; 1499 1500 // Can a compiler initialize a new object without store barriers? 1501 // This permission only extends from the creation of a new object 1502 // via a TLAB up to the first subsequent safepoint. If such permission 1503 // is granted for this heap type, the compiler promises to call 1504 // defer_store_barrier() below on any slow path allocation of 1505 // a new object for which such initializing store barriers will 1506 // have been elided. G1, like CMS, allows this, but should be 1507 // ready to provide a compensating write barrier as necessary 1508 // if that storage came out of a non-young region. The efficiency 1509 // of this implementation depends crucially on being able to 1510 // answer very efficiently in constant time whether a piece of 1511 // storage in the heap comes from a young region or not. 1512 // See ReduceInitialCardMarks. 1513 virtual bool can_elide_tlab_store_barriers() const { 1514 return true; 1515 } 1516 1517 virtual bool card_mark_must_follow_store() const { 1518 return true; 1519 } 1520 1521 bool is_in_young(const oop obj) { 1522 HeapRegion* hr = heap_region_containing(obj); 1523 return hr != NULL && hr->is_young(); 1524 } 1525 1526 #ifdef ASSERT 1527 virtual bool is_in_partial_collection(const void* p); 1528 #endif 1529 1530 virtual bool is_scavengable(const void* addr); 1531 1532 // We don't need barriers for initializing stores to objects 1533 // in the young gen: for the SATB pre-barrier, there is no 1534 // pre-value that needs to be remembered; for the remembered-set 1535 // update logging post-barrier, we don't maintain remembered set 1536 // information for young gen objects. 1537 virtual bool can_elide_initializing_store_barrier(oop new_obj) { 1538 return is_in_young(new_obj); 1539 } 1540 1541 // Returns "true" iff the given word_size is "very large". 1542 static bool isHumongous(size_t word_size) { 1543 // Note this has to be strictly greater-than as the TLABs 1544 // are capped at the humongous thresold and we want to 1545 // ensure that we don't try to allocate a TLAB as 1546 // humongous and that we don't allocate a humongous 1547 // object in a TLAB. 1548 return word_size > _humongous_object_threshold_in_words; 1549 } 1550 1551 // Update mod union table with the set of dirty cards. 1552 void updateModUnion(); 1553 1554 // Set the mod union bits corresponding to the given memRegion. Note 1555 // that this is always a safe operation, since it doesn't clear any 1556 // bits. 1557 void markModUnionRange(MemRegion mr); 1558 1559 // Records the fact that a marking phase is no longer in progress. 1560 void set_marking_complete() { 1561 _mark_in_progress = false; 1562 } 1563 void set_marking_started() { 1564 _mark_in_progress = true; 1565 } 1566 bool mark_in_progress() { 1567 return _mark_in_progress; 1568 } 1569 1570 // Print the maximum heap capacity. 1571 virtual size_t max_capacity() const; 1572 1573 virtual jlong millis_since_last_gc(); 1574 1575 // Perform any cleanup actions necessary before allowing a verification. 1576 virtual void prepare_for_verify(); 1577 1578 // Perform verification. 1579 1580 // vo == UsePrevMarking -> use "prev" marking information, 1581 // vo == UseNextMarking -> use "next" marking information 1582 // vo == UseMarkWord -> use the mark word in the object header 1583 // 1584 // NOTE: Only the "prev" marking information is guaranteed to be 1585 // consistent most of the time, so most calls to this should use 1586 // vo == UsePrevMarking. 1587 // Currently, there is only one case where this is called with 1588 // vo == UseNextMarking, which is to verify the "next" marking 1589 // information at the end of remark. 1590 // Currently there is only one place where this is called with 1591 // vo == UseMarkWord, which is to verify the marking during a 1592 // full GC. 1593 void verify(bool silent, VerifyOption vo); 1594 1595 // Override; it uses the "prev" marking information 1596 virtual void verify(bool silent); 1597 virtual void print_on(outputStream* st) const; 1598 virtual void print_extended_on(outputStream* st) const; 1599 1600 virtual void print_gc_threads_on(outputStream* st) const; 1601 virtual void gc_threads_do(ThreadClosure* tc) const; 1602 1603 // Override 1604 void print_tracing_info() const; 1605 1606 // The following two methods are helpful for debugging RSet issues. 1607 void print_cset_rsets() PRODUCT_RETURN; 1608 void print_all_rsets() PRODUCT_RETURN; 1609 1610 // Convenience function to be used in situations where the heap type can be 1611 // asserted to be this type. 1612 static G1CollectedHeap* heap(); 1613 1614 void set_region_short_lived_locked(HeapRegion* hr); 1615 // add appropriate methods for any other surv rate groups 1616 1617 YoungList* young_list() { return _young_list; } 1618 1619 // debugging 1620 bool check_young_list_well_formed() { 1621 return _young_list->check_list_well_formed(); 1622 } 1623 1624 bool check_young_list_empty(bool check_heap, 1625 bool check_sample = true); 1626 1627 // *** Stuff related to concurrent marking. It's not clear to me that so 1628 // many of these need to be public. 1629 1630 // The functions below are helper functions that a subclass of 1631 // "CollectedHeap" can use in the implementation of its virtual 1632 // functions. 1633 // This performs a concurrent marking of the live objects in a 1634 // bitmap off to the side. 1635 void doConcurrentMark(); 1636 1637 bool isMarkedPrev(oop obj) const; 1638 bool isMarkedNext(oop obj) const; 1639 1640 // Determine if an object is dead, given the object and also 1641 // the region to which the object belongs. An object is dead 1642 // iff a) it was not allocated since the last mark and b) it 1643 // is not marked. 1644 1645 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1646 return 1647 !hr->obj_allocated_since_prev_marking(obj) && 1648 !isMarkedPrev(obj); 1649 } 1650 1651 // This function returns true when an object has been 1652 // around since the previous marking and hasn't yet 1653 // been marked during this marking. 1654 1655 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1656 return 1657 !hr->obj_allocated_since_next_marking(obj) && 1658 !isMarkedNext(obj); 1659 } 1660 1661 // Determine if an object is dead, given only the object itself. 1662 // This will find the region to which the object belongs and 1663 // then call the region version of the same function. 1664 1665 // Added if it is NULL it isn't dead. 1666 1667 bool is_obj_dead(const oop obj) const { 1668 const HeapRegion* hr = heap_region_containing(obj); 1669 if (hr == NULL) { 1670 if (obj == NULL) return false; 1671 else return true; 1672 } 1673 else return is_obj_dead(obj, hr); 1674 } 1675 1676 bool is_obj_ill(const oop obj) const { 1677 const HeapRegion* hr = heap_region_containing(obj); 1678 if (hr == NULL) { 1679 if (obj == NULL) return false; 1680 else return true; 1681 } 1682 else return is_obj_ill(obj, hr); 1683 } 1684 1685 // The methods below are here for convenience and dispatch the 1686 // appropriate method depending on value of the given VerifyOption 1687 // parameter. The options for that parameter are: 1688 // 1689 // vo == UsePrevMarking -> use "prev" marking information, 1690 // vo == UseNextMarking -> use "next" marking information, 1691 // vo == UseMarkWord -> use mark word from object header 1692 1693 bool is_obj_dead_cond(const oop obj, 1694 const HeapRegion* hr, 1695 const VerifyOption vo) const { 1696 switch (vo) { 1697 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 1698 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 1699 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 1700 default: ShouldNotReachHere(); 1701 } 1702 return false; // keep some compilers happy 1703 } 1704 1705 bool is_obj_dead_cond(const oop obj, 1706 const VerifyOption vo) const { 1707 switch (vo) { 1708 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 1709 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 1710 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 1711 default: ShouldNotReachHere(); 1712 } 1713 return false; // keep some compilers happy 1714 } 1715 1716 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1717 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1718 bool is_marked(oop obj, VerifyOption vo); 1719 const char* top_at_mark_start_str(VerifyOption vo); 1720 1721 // The following is just to alert the verification code 1722 // that a full collection has occurred and that the 1723 // remembered sets are no longer up to date. 1724 bool _full_collection; 1725 void set_full_collection() { _full_collection = true;} 1726 void clear_full_collection() {_full_collection = false;} 1727 bool full_collection() {return _full_collection;} 1728 1729 ConcurrentMark* concurrent_mark() const { return _cm; } 1730 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1731 1732 // The dirty cards region list is used to record a subset of regions 1733 // whose cards need clearing. The list if populated during the 1734 // remembered set scanning and drained during the card table 1735 // cleanup. Although the methods are reentrant, population/draining 1736 // phases must not overlap. For synchronization purposes the last 1737 // element on the list points to itself. 1738 HeapRegion* _dirty_cards_region_list; 1739 void push_dirty_cards_region(HeapRegion* hr); 1740 HeapRegion* pop_dirty_cards_region(); 1741 1742 public: 1743 void stop_conc_gc_threads(); 1744 1745 size_t pending_card_num(); 1746 size_t cards_scanned(); 1747 1748 protected: 1749 size_t _max_heap_capacity; 1750 }; 1751 1752 class G1ParGCAllocBuffer: public ParGCAllocBuffer { 1753 private: 1754 bool _retired; 1755 1756 public: 1757 G1ParGCAllocBuffer(size_t gclab_word_size); 1758 1759 void set_buf(HeapWord* buf) { 1760 ParGCAllocBuffer::set_buf(buf); 1761 _retired = false; 1762 } 1763 1764 void retire(bool end_of_gc, bool retain) { 1765 if (_retired) 1766 return; 1767 ParGCAllocBuffer::retire(end_of_gc, retain); 1768 _retired = true; 1769 } 1770 }; 1771 1772 class G1ParScanThreadState : public StackObj { 1773 protected: 1774 G1CollectedHeap* _g1h; 1775 RefToScanQueue* _refs; 1776 DirtyCardQueue _dcq; 1777 CardTableModRefBS* _ct_bs; 1778 G1RemSet* _g1_rem; 1779 1780 G1ParGCAllocBuffer _surviving_alloc_buffer; 1781 G1ParGCAllocBuffer _tenured_alloc_buffer; 1782 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount]; 1783 ageTable _age_table; 1784 1785 size_t _alloc_buffer_waste; 1786 size_t _undo_waste; 1787 1788 OopsInHeapRegionClosure* _evac_failure_cl; 1789 G1ParScanHeapEvacClosure* _evac_cl; 1790 G1ParScanPartialArrayClosure* _partial_scan_cl; 1791 1792 int _hash_seed; 1793 uint _queue_num; 1794 1795 size_t _term_attempts; 1796 1797 double _start; 1798 double _start_strong_roots; 1799 double _strong_roots_time; 1800 double _start_term; 1801 double _term_time; 1802 1803 // Map from young-age-index (0 == not young, 1 is youngest) to 1804 // surviving words. base is what we get back from the malloc call 1805 size_t* _surviving_young_words_base; 1806 // this points into the array, as we use the first few entries for padding 1807 size_t* _surviving_young_words; 1808 1809 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t)) 1810 1811 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; } 1812 1813 void add_to_undo_waste(size_t waste) { _undo_waste += waste; } 1814 1815 DirtyCardQueue& dirty_card_queue() { return _dcq; } 1816 CardTableModRefBS* ctbs() { return _ct_bs; } 1817 1818 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) { 1819 if (!from->is_survivor()) { 1820 _g1_rem->par_write_ref(from, p, tid); 1821 } 1822 } 1823 1824 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) { 1825 // If the new value of the field points to the same region or 1826 // is the to-space, we don't need to include it in the Rset updates. 1827 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) { 1828 size_t card_index = ctbs()->index_for(p); 1829 // If the card hasn't been added to the buffer, do it. 1830 if (ctbs()->mark_card_deferred(card_index)) { 1831 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index)); 1832 } 1833 } 1834 } 1835 1836 public: 1837 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num); 1838 1839 ~G1ParScanThreadState() { 1840 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC); 1841 } 1842 1843 RefToScanQueue* refs() { return _refs; } 1844 ageTable* age_table() { return &_age_table; } 1845 1846 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) { 1847 return _alloc_buffers[purpose]; 1848 } 1849 1850 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; } 1851 size_t undo_waste() const { return _undo_waste; } 1852 1853 #ifdef ASSERT 1854 bool verify_ref(narrowOop* ref) const; 1855 bool verify_ref(oop* ref) const; 1856 bool verify_task(StarTask ref) const; 1857 #endif // ASSERT 1858 1859 template <class T> void push_on_queue(T* ref) { 1860 assert(verify_ref(ref), "sanity"); 1861 refs()->push(ref); 1862 } 1863 1864 template <class T> void update_rs(HeapRegion* from, T* p, int tid) { 1865 if (G1DeferredRSUpdate) { 1866 deferred_rs_update(from, p, tid); 1867 } else { 1868 immediate_rs_update(from, p, tid); 1869 } 1870 } 1871 1872 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) { 1873 HeapWord* obj = NULL; 1874 size_t gclab_word_size = _g1h->desired_plab_sz(purpose); 1875 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) { 1876 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose); 1877 add_to_alloc_buffer_waste(alloc_buf->words_remaining()); 1878 alloc_buf->retire(false /* end_of_gc */, false /* retain */); 1879 1880 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size); 1881 if (buf == NULL) return NULL; // Let caller handle allocation failure. 1882 // Otherwise. 1883 alloc_buf->set_word_size(gclab_word_size); 1884 alloc_buf->set_buf(buf); 1885 1886 obj = alloc_buf->allocate(word_sz); 1887 assert(obj != NULL, "buffer was definitely big enough..."); 1888 } else { 1889 obj = _g1h->par_allocate_during_gc(purpose, word_sz); 1890 } 1891 return obj; 1892 } 1893 1894 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) { 1895 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz); 1896 if (obj != NULL) return obj; 1897 return allocate_slow(purpose, word_sz); 1898 } 1899 1900 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) { 1901 if (alloc_buffer(purpose)->contains(obj)) { 1902 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1), 1903 "should contain whole object"); 1904 alloc_buffer(purpose)->undo_allocation(obj, word_sz); 1905 } else { 1906 CollectedHeap::fill_with_object(obj, word_sz); 1907 add_to_undo_waste(word_sz); 1908 } 1909 } 1910 1911 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) { 1912 _evac_failure_cl = evac_failure_cl; 1913 } 1914 OopsInHeapRegionClosure* evac_failure_closure() { 1915 return _evac_failure_cl; 1916 } 1917 1918 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) { 1919 _evac_cl = evac_cl; 1920 } 1921 1922 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) { 1923 _partial_scan_cl = partial_scan_cl; 1924 } 1925 1926 int* hash_seed() { return &_hash_seed; } 1927 uint queue_num() { return _queue_num; } 1928 1929 size_t term_attempts() const { return _term_attempts; } 1930 void note_term_attempt() { _term_attempts++; } 1931 1932 void start_strong_roots() { 1933 _start_strong_roots = os::elapsedTime(); 1934 } 1935 void end_strong_roots() { 1936 _strong_roots_time += (os::elapsedTime() - _start_strong_roots); 1937 } 1938 double strong_roots_time() const { return _strong_roots_time; } 1939 1940 void start_term_time() { 1941 note_term_attempt(); 1942 _start_term = os::elapsedTime(); 1943 } 1944 void end_term_time() { 1945 _term_time += (os::elapsedTime() - _start_term); 1946 } 1947 double term_time() const { return _term_time; } 1948 1949 double elapsed_time() const { 1950 return os::elapsedTime() - _start; 1951 } 1952 1953 static void 1954 print_termination_stats_hdr(outputStream* const st = gclog_or_tty); 1955 void 1956 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const; 1957 1958 size_t* surviving_young_words() { 1959 // We add on to hide entry 0 which accumulates surviving words for 1960 // age -1 regions (i.e. non-young ones) 1961 return _surviving_young_words; 1962 } 1963 1964 void retire_alloc_buffers() { 1965 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) { 1966 size_t waste = _alloc_buffers[ap]->words_remaining(); 1967 add_to_alloc_buffer_waste(waste); 1968 _alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap), 1969 true /* end_of_gc */, 1970 false /* retain */); 1971 } 1972 } 1973 1974 template <class T> void deal_with_reference(T* ref_to_scan) { 1975 if (has_partial_array_mask(ref_to_scan)) { 1976 _partial_scan_cl->do_oop_nv(ref_to_scan); 1977 } else { 1978 // Note: we can use "raw" versions of "region_containing" because 1979 // "obj_to_scan" is definitely in the heap, and is not in a 1980 // humongous region. 1981 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan); 1982 _evac_cl->set_region(r); 1983 _evac_cl->do_oop_nv(ref_to_scan); 1984 } 1985 } 1986 1987 void deal_with_reference(StarTask ref) { 1988 assert(verify_task(ref), "sanity"); 1989 if (ref.is_narrow()) { 1990 deal_with_reference((narrowOop*)ref); 1991 } else { 1992 deal_with_reference((oop*)ref); 1993 } 1994 } 1995 1996 public: 1997 void trim_queue(); 1998 }; 1999 2000 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP