1 /* 2 * Copyright (c) 2001, 2012, 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(); 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 // These are macros so that, if the assert fires, we get the correct 412 // line number, file, etc. 413 414 #define heap_locking_asserts_err_msg(_extra_message_) \ 415 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 416 (_extra_message_), \ 417 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 418 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 419 BOOL_TO_STR(Thread::current()->is_VM_thread())) 420 421 #define assert_heap_locked() \ 422 do { \ 423 assert(Heap_lock->owned_by_self(), \ 424 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \ 425 } while (0) 426 427 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 428 do { \ 429 assert(Heap_lock->owned_by_self() || \ 430 (SafepointSynchronize::is_at_safepoint() && \ 431 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 432 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \ 433 "should be at a safepoint")); \ 434 } while (0) 435 436 #define assert_heap_locked_and_not_at_safepoint() \ 437 do { \ 438 assert(Heap_lock->owned_by_self() && \ 439 !SafepointSynchronize::is_at_safepoint(), \ 440 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \ 441 "should not be at a safepoint")); \ 442 } while (0) 443 444 #define assert_heap_not_locked() \ 445 do { \ 446 assert(!Heap_lock->owned_by_self(), \ 447 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \ 448 } while (0) 449 450 #define assert_heap_not_locked_and_not_at_safepoint() \ 451 do { \ 452 assert(!Heap_lock->owned_by_self() && \ 453 !SafepointSynchronize::is_at_safepoint(), \ 454 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \ 455 "should not be at a safepoint")); \ 456 } while (0) 457 458 #define assert_at_safepoint(_should_be_vm_thread_) \ 459 do { \ 460 assert(SafepointSynchronize::is_at_safepoint() && \ 461 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 462 heap_locking_asserts_err_msg("should be at a safepoint")); \ 463 } while (0) 464 465 #define assert_not_at_safepoint() \ 466 do { \ 467 assert(!SafepointSynchronize::is_at_safepoint(), \ 468 heap_locking_asserts_err_msg("should not be at a safepoint")); \ 469 } while (0) 470 471 protected: 472 473 // The young region list. 474 YoungList* _young_list; 475 476 // The current policy object for the collector. 477 G1CollectorPolicy* _g1_policy; 478 479 // This is the second level of trying to allocate a new region. If 480 // new_region() didn't find a region on the free_list, this call will 481 // check whether there's anything available on the 482 // secondary_free_list and/or wait for more regions to appear on 483 // that list, if _free_regions_coming is set. 484 HeapRegion* new_region_try_secondary_free_list(); 485 486 // Try to allocate a single non-humongous HeapRegion sufficient for 487 // an allocation of the given word_size. If do_expand is true, 488 // attempt to expand the heap if necessary to satisfy the allocation 489 // request. 490 HeapRegion* new_region(size_t word_size, bool do_expand); 491 492 // Attempt to satisfy a humongous allocation request of the given 493 // size by finding a contiguous set of free regions of num_regions 494 // length and remove them from the master free list. Return the 495 // index of the first region or G1_NULL_HRS_INDEX if the search 496 // was unsuccessful. 497 uint humongous_obj_allocate_find_first(uint num_regions, 498 size_t word_size); 499 500 // Initialize a contiguous set of free regions of length num_regions 501 // and starting at index first so that they appear as a single 502 // humongous region. 503 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 504 uint num_regions, 505 size_t word_size); 506 507 // Attempt to allocate a humongous object of the given size. Return 508 // NULL if unsuccessful. 509 HeapWord* humongous_obj_allocate(size_t word_size); 510 511 // The following two methods, allocate_new_tlab() and 512 // mem_allocate(), are the two main entry points from the runtime 513 // into the G1's allocation routines. They have the following 514 // assumptions: 515 // 516 // * They should both be called outside safepoints. 517 // 518 // * They should both be called without holding the Heap_lock. 519 // 520 // * All allocation requests for new TLABs should go to 521 // allocate_new_tlab(). 522 // 523 // * All non-TLAB allocation requests should go to mem_allocate(). 524 // 525 // * If either call cannot satisfy the allocation request using the 526 // current allocating region, they will try to get a new one. If 527 // this fails, they will attempt to do an evacuation pause and 528 // retry the allocation. 529 // 530 // * If all allocation attempts fail, even after trying to schedule 531 // an evacuation pause, allocate_new_tlab() will return NULL, 532 // whereas mem_allocate() will attempt a heap expansion and/or 533 // schedule a Full GC. 534 // 535 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 536 // should never be called with word_size being humongous. All 537 // humongous allocation requests should go to mem_allocate() which 538 // will satisfy them with a special path. 539 540 virtual HeapWord* allocate_new_tlab(size_t word_size); 541 542 virtual HeapWord* mem_allocate(size_t word_size, 543 bool* gc_overhead_limit_was_exceeded); 544 545 // The following three methods take a gc_count_before_ret 546 // parameter which is used to return the GC count if the method 547 // returns NULL. Given that we are required to read the GC count 548 // while holding the Heap_lock, and these paths will take the 549 // Heap_lock at some point, it's easier to get them to read the GC 550 // count while holding the Heap_lock before they return NULL instead 551 // of the caller (namely: mem_allocate()) having to also take the 552 // Heap_lock just to read the GC count. 553 554 // First-level mutator allocation attempt: try to allocate out of 555 // the mutator alloc region without taking the Heap_lock. This 556 // should only be used for non-humongous allocations. 557 inline HeapWord* attempt_allocation(size_t word_size, 558 unsigned int* gc_count_before_ret); 559 560 // Second-level mutator allocation attempt: take the Heap_lock and 561 // retry the allocation attempt, potentially scheduling a GC 562 // pause. This should only be used for non-humongous allocations. 563 HeapWord* attempt_allocation_slow(size_t word_size, 564 unsigned int* gc_count_before_ret); 565 566 // Takes the Heap_lock and attempts a humongous allocation. It can 567 // potentially schedule a GC pause. 568 HeapWord* attempt_allocation_humongous(size_t word_size, 569 unsigned int* gc_count_before_ret); 570 571 // Allocation attempt that should be called during safepoints (e.g., 572 // at the end of a successful GC). expect_null_mutator_alloc_region 573 // specifies whether the mutator alloc region is expected to be NULL 574 // or not. 575 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 576 bool expect_null_mutator_alloc_region); 577 578 // It dirties the cards that cover the block so that so that the post 579 // write barrier never queues anything when updating objects on this 580 // block. It is assumed (and in fact we assert) that the block 581 // belongs to a young region. 582 inline void dirty_young_block(HeapWord* start, size_t word_size); 583 584 // Allocate blocks during garbage collection. Will ensure an 585 // allocation region, either by picking one or expanding the 586 // heap, and then allocate a block of the given size. The block 587 // may not be a humongous - it must fit into a single heap region. 588 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size); 589 590 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose, 591 HeapRegion* alloc_region, 592 bool par, 593 size_t word_size); 594 595 // Ensure that no further allocations can happen in "r", bearing in mind 596 // that parallel threads might be attempting allocations. 597 void par_allocate_remaining_space(HeapRegion* r); 598 599 // Allocation attempt during GC for a survivor object / PLAB. 600 inline HeapWord* survivor_attempt_allocation(size_t word_size); 601 602 // Allocation attempt during GC for an old object / PLAB. 603 inline HeapWord* old_attempt_allocation(size_t word_size); 604 605 // These methods are the "callbacks" from the G1AllocRegion class. 606 607 // For mutator alloc regions. 608 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 609 void retire_mutator_alloc_region(HeapRegion* alloc_region, 610 size_t allocated_bytes); 611 612 // For GC alloc regions. 613 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 614 GCAllocPurpose ap); 615 void retire_gc_alloc_region(HeapRegion* alloc_region, 616 size_t allocated_bytes, GCAllocPurpose ap); 617 618 // - if explicit_gc is true, the GC is for a System.gc() or a heap 619 // inspection request and should collect the entire heap 620 // - if clear_all_soft_refs is true, all soft references should be 621 // cleared during the GC 622 // - if explicit_gc is false, word_size describes the allocation that 623 // the GC should attempt (at least) to satisfy 624 // - it returns false if it is unable to do the collection due to the 625 // GC locker being active, true otherwise 626 bool do_collection(bool explicit_gc, 627 bool clear_all_soft_refs, 628 size_t word_size); 629 630 // Callback from VM_G1CollectFull operation. 631 // Perform a full collection. 632 virtual void do_full_collection(bool clear_all_soft_refs); 633 634 // Resize the heap if necessary after a full collection. If this is 635 // after a collect-for allocation, "word_size" is the allocation size, 636 // and will be considered part of the used portion of the heap. 637 void resize_if_necessary_after_full_collection(size_t word_size); 638 639 // Callback from VM_G1CollectForAllocation operation. 640 // This function does everything necessary/possible to satisfy a 641 // failed allocation request (including collection, expansion, etc.) 642 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded); 643 644 // Attempting to expand the heap sufficiently 645 // to support an allocation of the given "word_size". If 646 // successful, perform the allocation and return the address of the 647 // allocated block, or else "NULL". 648 HeapWord* expand_and_allocate(size_t word_size); 649 650 // Process any reference objects discovered during 651 // an incremental evacuation pause. 652 void process_discovered_references(); 653 654 // Enqueue any remaining discovered references 655 // after processing. 656 void enqueue_discovered_references(); 657 658 public: 659 660 G1MonitoringSupport* g1mm() { 661 assert(_g1mm != NULL, "should have been initialized"); 662 return _g1mm; 663 } 664 665 // Expand the garbage-first heap by at least the given size (in bytes!). 666 // Returns true if the heap was expanded by the requested amount; 667 // false otherwise. 668 // (Rounds up to a HeapRegion boundary.) 669 bool expand(size_t expand_bytes); 670 671 // Do anything common to GC's. 672 virtual void gc_prologue(bool full); 673 virtual void gc_epilogue(bool full); 674 675 // We register a region with the fast "in collection set" test. We 676 // simply set to true the array slot corresponding to this region. 677 void register_region_with_in_cset_fast_test(HeapRegion* r) { 678 assert(_in_cset_fast_test_base != NULL, "sanity"); 679 assert(r->in_collection_set(), "invariant"); 680 uint index = r->hrs_index(); 681 assert(index < _in_cset_fast_test_length, "invariant"); 682 assert(!_in_cset_fast_test_base[index], "invariant"); 683 _in_cset_fast_test_base[index] = true; 684 } 685 686 // This is a fast test on whether a reference points into the 687 // collection set or not. It does not assume that the reference 688 // points into the heap; if it doesn't, it will return false. 689 bool in_cset_fast_test(oop obj) { 690 assert(_in_cset_fast_test != NULL, "sanity"); 691 if (_g1_committed.contains((HeapWord*) obj)) { 692 // no need to subtract the bottom of the heap from obj, 693 // _in_cset_fast_test is biased 694 uintx index = (uintx) obj >> HeapRegion::LogOfHRGrainBytes; 695 bool ret = _in_cset_fast_test[index]; 696 // let's make sure the result is consistent with what the slower 697 // test returns 698 assert( ret || !obj_in_cs(obj), "sanity"); 699 assert(!ret || obj_in_cs(obj), "sanity"); 700 return ret; 701 } else { 702 return false; 703 } 704 } 705 706 void clear_cset_fast_test() { 707 assert(_in_cset_fast_test_base != NULL, "sanity"); 708 memset(_in_cset_fast_test_base, false, 709 (size_t) _in_cset_fast_test_length * sizeof(bool)); 710 } 711 712 // This is called at the start of either a concurrent cycle or a Full 713 // GC to update the number of old marking cycles started. 714 void increment_old_marking_cycles_started(); 715 716 // This is called at the end of either a concurrent cycle or a Full 717 // GC to update the number of old marking cycles completed. Those two 718 // can happen in a nested fashion, i.e., we start a concurrent 719 // cycle, a Full GC happens half-way through it which ends first, 720 // and then the cycle notices that a Full GC happened and ends 721 // too. The concurrent parameter is a boolean to help us do a bit 722 // tighter consistency checking in the method. If concurrent is 723 // false, the caller is the inner caller in the nesting (i.e., the 724 // Full GC). If concurrent is true, the caller is the outer caller 725 // in this nesting (i.e., the concurrent cycle). Further nesting is 726 // not currently supported. The end of this call also notifies 727 // the FullGCCount_lock in case a Java thread is waiting for a full 728 // GC to happen (e.g., it called System.gc() with 729 // +ExplicitGCInvokesConcurrent). 730 void increment_old_marking_cycles_completed(bool concurrent); 731 732 unsigned int old_marking_cycles_completed() { 733 return _old_marking_cycles_completed; 734 } 735 736 G1HRPrinter* hr_printer() { return &_hr_printer; } 737 738 protected: 739 740 // Shrink the garbage-first heap by at most the given size (in bytes!). 741 // (Rounds down to a HeapRegion boundary.) 742 virtual void shrink(size_t expand_bytes); 743 void shrink_helper(size_t expand_bytes); 744 745 #if TASKQUEUE_STATS 746 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 747 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 748 void reset_taskqueue_stats(); 749 #endif // TASKQUEUE_STATS 750 751 // Schedule the VM operation that will do an evacuation pause to 752 // satisfy an allocation request of word_size. *succeeded will 753 // return whether the VM operation was successful (it did do an 754 // evacuation pause) or not (another thread beat us to it or the GC 755 // locker was active). Given that we should not be holding the 756 // Heap_lock when we enter this method, we will pass the 757 // gc_count_before (i.e., total_collections()) as a parameter since 758 // it has to be read while holding the Heap_lock. Currently, both 759 // methods that call do_collection_pause() release the Heap_lock 760 // before the call, so it's easy to read gc_count_before just before. 761 HeapWord* do_collection_pause(size_t word_size, 762 unsigned int gc_count_before, 763 bool* succeeded); 764 765 // The guts of the incremental collection pause, executed by the vm 766 // thread. It returns false if it is unable to do the collection due 767 // to the GC locker being active, true otherwise 768 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 769 770 // Actually do the work of evacuating the collection set. 771 void evacuate_collection_set(); 772 773 // The g1 remembered set of the heap. 774 G1RemSet* _g1_rem_set; 775 // And it's mod ref barrier set, used to track updates for the above. 776 ModRefBarrierSet* _mr_bs; 777 778 // A set of cards that cover the objects for which the Rsets should be updated 779 // concurrently after the collection. 780 DirtyCardQueueSet _dirty_card_queue_set; 781 782 // The Heap Region Rem Set Iterator. 783 HeapRegionRemSetIterator** _rem_set_iterator; 784 785 // The closure used to refine a single card. 786 RefineCardTableEntryClosure* _refine_cte_cl; 787 788 // A function to check the consistency of dirty card logs. 789 void check_ct_logs_at_safepoint(); 790 791 // A DirtyCardQueueSet that is used to hold cards that contain 792 // references into the current collection set. This is used to 793 // update the remembered sets of the regions in the collection 794 // set in the event of an evacuation failure. 795 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 796 797 // After a collection pause, make the regions in the CS into free 798 // regions. 799 void free_collection_set(HeapRegion* cs_head); 800 801 // Abandon the current collection set without recording policy 802 // statistics or updating free lists. 803 void abandon_collection_set(HeapRegion* cs_head); 804 805 // Applies "scan_non_heap_roots" to roots outside the heap, 806 // "scan_rs" to roots inside the heap (having done "set_region" to 807 // indicate the region in which the root resides), 808 // and does "scan_metadata" If "scan_rs" is 809 // NULL, then this step is skipped. The "worker_i" 810 // param is for use with parallel roots processing, and should be 811 // the "i" of the calling parallel worker thread's work(i) function. 812 // In the sequential case this param will be ignored. 813 void g1_process_strong_roots(bool is_scavenging, 814 ScanningOption so, 815 OopClosure* scan_non_heap_roots, 816 OopsInHeapRegionClosure* scan_rs, 817 G1KlassScanClosure* scan_klasses, 818 int worker_i); 819 820 // Apply "blk" to all the weak roots of the system. These include 821 // JNI weak roots, the code cache, system dictionary, symbol table, 822 // string table, and referents of reachable weak refs. 823 void g1_process_weak_roots(OopClosure* root_closure, 824 OopClosure* non_root_closure); 825 826 // Frees a non-humongous region by initializing its contents and 827 // adding it to the free list that's passed as a parameter (this is 828 // usually a local list which will be appended to the master free 829 // list later). The used bytes of freed regions are accumulated in 830 // pre_used. If par is true, the region's RSet will not be freed 831 // up. The assumption is that this will be done later. 832 void free_region(HeapRegion* hr, 833 size_t* pre_used, 834 FreeRegionList* free_list, 835 bool par); 836 837 // Frees a humongous region by collapsing it into individual regions 838 // and calling free_region() for each of them. The freed regions 839 // will be added to the free list that's passed as a parameter (this 840 // is usually a local list which will be appended to the master free 841 // list later). The used bytes of freed regions are accumulated in 842 // pre_used. If par is true, the region's RSet will not be freed 843 // up. The assumption is that this will be done later. 844 void free_humongous_region(HeapRegion* hr, 845 size_t* pre_used, 846 FreeRegionList* free_list, 847 HumongousRegionSet* humongous_proxy_set, 848 bool par); 849 850 // Notifies all the necessary spaces that the committed space has 851 // been updated (either expanded or shrunk). It should be called 852 // after _g1_storage is updated. 853 void update_committed_space(HeapWord* old_end, HeapWord* new_end); 854 855 // The concurrent marker (and the thread it runs in.) 856 ConcurrentMark* _cm; 857 ConcurrentMarkThread* _cmThread; 858 bool _mark_in_progress; 859 860 // The concurrent refiner. 861 ConcurrentG1Refine* _cg1r; 862 863 // The parallel task queues 864 RefToScanQueueSet *_task_queues; 865 866 // True iff a evacuation has failed in the current collection. 867 bool _evacuation_failed; 868 869 // Set the attribute indicating whether evacuation has failed in the 870 // current collection. 871 void set_evacuation_failed(bool b) { _evacuation_failed = b; } 872 873 // Failed evacuations cause some logical from-space objects to have 874 // forwarding pointers to themselves. Reset them. 875 void remove_self_forwarding_pointers(); 876 877 // When one is non-null, so is the other. Together, they each pair is 878 // an object with a preserved mark, and its mark value. 879 GrowableArray<oop>* _objs_with_preserved_marks; 880 GrowableArray<markOop>* _preserved_marks_of_objs; 881 882 // Preserve the mark of "obj", if necessary, in preparation for its mark 883 // word being overwritten with a self-forwarding-pointer. 884 void preserve_mark_if_necessary(oop obj, markOop m); 885 886 // The stack of evac-failure objects left to be scanned. 887 GrowableArray<oop>* _evac_failure_scan_stack; 888 // The closure to apply to evac-failure objects. 889 890 OopsInHeapRegionClosure* _evac_failure_closure; 891 // Set the field above. 892 void 893 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) { 894 _evac_failure_closure = evac_failure_closure; 895 } 896 897 // Push "obj" on the scan stack. 898 void push_on_evac_failure_scan_stack(oop obj); 899 // Process scan stack entries until the stack is empty. 900 void drain_evac_failure_scan_stack(); 901 // True iff an invocation of "drain_scan_stack" is in progress; to 902 // prevent unnecessary recursion. 903 bool _drain_in_progress; 904 905 // Do any necessary initialization for evacuation-failure handling. 906 // "cl" is the closure that will be used to process evac-failure 907 // objects. 908 void init_for_evac_failure(OopsInHeapRegionClosure* cl); 909 // Do any necessary cleanup for evacuation-failure handling data 910 // structures. 911 void finalize_for_evac_failure(); 912 913 // An attempt to evacuate "obj" has failed; take necessary steps. 914 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj); 915 void handle_evacuation_failure_common(oop obj, markOop m); 916 917 #ifndef PRODUCT 918 // Support for forcing evacuation failures. Analogous to 919 // PromotionFailureALot for the other collectors. 920 921 // Records whether G1EvacuationFailureALot should be in effect 922 // for the current GC 923 bool _evacuation_failure_alot_for_current_gc; 924 925 // Used to record the GC number for interval checking when 926 // determining whether G1EvaucationFailureALot is in effect 927 // for the current GC. 928 size_t _evacuation_failure_alot_gc_number; 929 930 // Count of the number of evacuations between failures. 931 volatile size_t _evacuation_failure_alot_count; 932 933 // Set whether G1EvacuationFailureALot should be in effect 934 // for the current GC (based upon the type of GC and which 935 // command line flags are set); 936 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 937 bool during_initial_mark, 938 bool during_marking); 939 940 inline void set_evacuation_failure_alot_for_current_gc(); 941 942 // Return true if it's time to cause an evacuation failure. 943 inline bool evacuation_should_fail(); 944 945 // Reset the G1EvacuationFailureALot counters. Should be called at 946 // the end of an evacuation pause in which an evacuation failure ocurred. 947 inline void reset_evacuation_should_fail(); 948 #endif // !PRODUCT 949 950 // ("Weak") Reference processing support. 951 // 952 // G1 has 2 instances of the referece processor class. One 953 // (_ref_processor_cm) handles reference object discovery 954 // and subsequent processing during concurrent marking cycles. 955 // 956 // The other (_ref_processor_stw) handles reference object 957 // discovery and processing during full GCs and incremental 958 // evacuation pauses. 959 // 960 // During an incremental pause, reference discovery will be 961 // temporarily disabled for _ref_processor_cm and will be 962 // enabled for _ref_processor_stw. At the end of the evacuation 963 // pause references discovered by _ref_processor_stw will be 964 // processed and discovery will be disabled. The previous 965 // setting for reference object discovery for _ref_processor_cm 966 // will be re-instated. 967 // 968 // At the start of marking: 969 // * Discovery by the CM ref processor is verified to be inactive 970 // and it's discovered lists are empty. 971 // * Discovery by the CM ref processor is then enabled. 972 // 973 // At the end of marking: 974 // * Any references on the CM ref processor's discovered 975 // lists are processed (possibly MT). 976 // 977 // At the start of full GC we: 978 // * Disable discovery by the CM ref processor and 979 // empty CM ref processor's discovered lists 980 // (without processing any entries). 981 // * Verify that the STW ref processor is inactive and it's 982 // discovered lists are empty. 983 // * Temporarily set STW ref processor discovery as single threaded. 984 // * Temporarily clear the STW ref processor's _is_alive_non_header 985 // field. 986 // * Finally enable discovery by the STW ref processor. 987 // 988 // The STW ref processor is used to record any discovered 989 // references during the full GC. 990 // 991 // At the end of a full GC we: 992 // * Enqueue any reference objects discovered by the STW ref processor 993 // that have non-live referents. This has the side-effect of 994 // making the STW ref processor inactive by disabling discovery. 995 // * Verify that the CM ref processor is still inactive 996 // and no references have been placed on it's discovered 997 // lists (also checked as a precondition during initial marking). 998 999 // The (stw) reference processor... 1000 ReferenceProcessor* _ref_processor_stw; 1001 1002 // During reference object discovery, the _is_alive_non_header 1003 // closure (if non-null) is applied to the referent object to 1004 // determine whether the referent is live. If so then the 1005 // reference object does not need to be 'discovered' and can 1006 // be treated as a regular oop. This has the benefit of reducing 1007 // the number of 'discovered' reference objects that need to 1008 // be processed. 1009 // 1010 // Instance of the is_alive closure for embedding into the 1011 // STW reference processor as the _is_alive_non_header field. 1012 // Supplying a value for the _is_alive_non_header field is 1013 // optional but doing so prevents unnecessary additions to 1014 // the discovered lists during reference discovery. 1015 G1STWIsAliveClosure _is_alive_closure_stw; 1016 1017 // The (concurrent marking) reference processor... 1018 ReferenceProcessor* _ref_processor_cm; 1019 1020 // Instance of the concurrent mark is_alive closure for embedding 1021 // into the Concurrent Marking reference processor as the 1022 // _is_alive_non_header field. Supplying a value for the 1023 // _is_alive_non_header field is optional but doing so prevents 1024 // unnecessary additions to the discovered lists during reference 1025 // discovery. 1026 G1CMIsAliveClosure _is_alive_closure_cm; 1027 1028 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 1029 HeapRegion** _worker_cset_start_region; 1030 1031 // Time stamp to validate the regions recorded in the cache 1032 // used by G1CollectedHeap::start_cset_region_for_worker(). 1033 // The heap region entry for a given worker is valid iff 1034 // the associated time stamp value matches the current value 1035 // of G1CollectedHeap::_gc_time_stamp. 1036 unsigned int* _worker_cset_start_region_time_stamp; 1037 1038 enum G1H_process_strong_roots_tasks { 1039 G1H_PS_filter_satb_buffers, 1040 G1H_PS_refProcessor_oops_do, 1041 // Leave this one last. 1042 G1H_PS_NumElements 1043 }; 1044 1045 SubTasksDone* _process_strong_tasks; 1046 1047 volatile bool _free_regions_coming; 1048 1049 public: 1050 1051 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; } 1052 1053 void set_refine_cte_cl_concurrency(bool concurrent); 1054 1055 RefToScanQueue *task_queue(int i) const; 1056 1057 // A set of cards where updates happened during the GC 1058 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 1059 1060 // A DirtyCardQueueSet that is used to hold cards that contain 1061 // references into the current collection set. This is used to 1062 // update the remembered sets of the regions in the collection 1063 // set in the event of an evacuation failure. 1064 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 1065 { return _into_cset_dirty_card_queue_set; } 1066 1067 // Create a G1CollectedHeap with the specified policy. 1068 // Must call the initialize method afterwards. 1069 // May not return if something goes wrong. 1070 G1CollectedHeap(G1CollectorPolicy* policy); 1071 1072 // Initialize the G1CollectedHeap to have the initial and 1073 // maximum sizes and remembered and barrier sets 1074 // specified by the policy object. 1075 jint initialize(); 1076 1077 // Initialize weak reference processing. 1078 virtual void ref_processing_init(); 1079 1080 void set_par_threads(uint t) { 1081 SharedHeap::set_par_threads(t); 1082 // Done in SharedHeap but oddly there are 1083 // two _process_strong_tasks's in a G1CollectedHeap 1084 // so do it here too. 1085 _process_strong_tasks->set_n_threads(t); 1086 } 1087 1088 // Set _n_par_threads according to a policy TBD. 1089 void set_par_threads(); 1090 1091 void set_n_termination(int t) { 1092 _process_strong_tasks->set_n_threads(t); 1093 } 1094 1095 virtual CollectedHeap::Name kind() const { 1096 return CollectedHeap::G1CollectedHeap; 1097 } 1098 1099 // The current policy object for the collector. 1100 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1101 1102 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } 1103 1104 // Adaptive size policy. No such thing for g1. 1105 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1106 1107 // The rem set and barrier set. 1108 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1109 ModRefBarrierSet* mr_bs() const { return _mr_bs; } 1110 1111 // The rem set iterator. 1112 HeapRegionRemSetIterator* rem_set_iterator(int i) { 1113 return _rem_set_iterator[i]; 1114 } 1115 1116 HeapRegionRemSetIterator* rem_set_iterator() { 1117 return _rem_set_iterator[0]; 1118 } 1119 1120 unsigned get_gc_time_stamp() { 1121 return _gc_time_stamp; 1122 } 1123 1124 void reset_gc_time_stamp() { 1125 _gc_time_stamp = 0; 1126 OrderAccess::fence(); 1127 // Clear the cached CSet starting regions and time stamps. 1128 // Their validity is dependent on the GC timestamp. 1129 clear_cset_start_regions(); 1130 } 1131 1132 void check_gc_time_stamps() PRODUCT_RETURN; 1133 1134 void increment_gc_time_stamp() { 1135 ++_gc_time_stamp; 1136 OrderAccess::fence(); 1137 } 1138 1139 // Reset the given region's GC timestamp. If it's starts humongous, 1140 // also reset the GC timestamp of its corresponding 1141 // continues humongous regions too. 1142 void reset_gc_time_stamps(HeapRegion* hr); 1143 1144 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1145 DirtyCardQueue* into_cset_dcq, 1146 bool concurrent, int worker_i); 1147 1148 // The shared block offset table array. 1149 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1150 1151 // Reference Processing accessors 1152 1153 // The STW reference processor.... 1154 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1155 1156 // The Concurent Marking reference processor... 1157 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1158 1159 virtual size_t capacity() const; 1160 virtual size_t used() const; 1161 // This should be called when we're not holding the heap lock. The 1162 // result might be a bit inaccurate. 1163 size_t used_unlocked() const; 1164 size_t recalculate_used() const; 1165 1166 // These virtual functions do the actual allocation. 1167 // Some heaps may offer a contiguous region for shared non-blocking 1168 // allocation, via inlined code (by exporting the address of the top and 1169 // end fields defining the extent of the contiguous allocation region.) 1170 // But G1CollectedHeap doesn't yet support this. 1171 1172 // Return an estimate of the maximum allocation that could be performed 1173 // without triggering any collection or expansion activity. In a 1174 // generational collector, for example, this is probably the largest 1175 // allocation that could be supported (without expansion) in the youngest 1176 // generation. It is "unsafe" because no locks are taken; the result 1177 // should be treated as an approximation, not a guarantee, for use in 1178 // heuristic resizing decisions. 1179 virtual size_t unsafe_max_alloc(); 1180 1181 virtual bool is_maximal_no_gc() const { 1182 return _g1_storage.uncommitted_size() == 0; 1183 } 1184 1185 // The total number of regions in the heap. 1186 uint n_regions() { return _hrs.length(); } 1187 1188 // The max number of regions in the heap. 1189 uint max_regions() { return _hrs.max_length(); } 1190 1191 // The number of regions that are completely free. 1192 uint free_regions() { return _free_list.length(); } 1193 1194 // The number of regions that are not completely free. 1195 uint used_regions() { return n_regions() - free_regions(); } 1196 1197 // The number of regions available for "regular" expansion. 1198 uint expansion_regions() { return _expansion_regions; } 1199 1200 // Factory method for HeapRegion instances. It will return NULL if 1201 // the allocation fails. 1202 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom); 1203 1204 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1205 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1206 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1207 void verify_dirty_young_regions() PRODUCT_RETURN; 1208 1209 // verify_region_sets() performs verification over the region 1210 // lists. It will be compiled in the product code to be used when 1211 // necessary (i.e., during heap verification). 1212 void verify_region_sets(); 1213 1214 // verify_region_sets_optional() is planted in the code for 1215 // list verification in non-product builds (and it can be enabled in 1216 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1). 1217 #if HEAP_REGION_SET_FORCE_VERIFY 1218 void verify_region_sets_optional() { 1219 verify_region_sets(); 1220 } 1221 #else // HEAP_REGION_SET_FORCE_VERIFY 1222 void verify_region_sets_optional() { } 1223 #endif // HEAP_REGION_SET_FORCE_VERIFY 1224 1225 #ifdef ASSERT 1226 bool is_on_master_free_list(HeapRegion* hr) { 1227 return hr->containing_set() == &_free_list; 1228 } 1229 1230 bool is_in_humongous_set(HeapRegion* hr) { 1231 return hr->containing_set() == &_humongous_set; 1232 } 1233 #endif // ASSERT 1234 1235 // Wrapper for the region list operations that can be called from 1236 // methods outside this class. 1237 1238 void secondary_free_list_add_as_tail(FreeRegionList* list) { 1239 _secondary_free_list.add_as_tail(list); 1240 } 1241 1242 void append_secondary_free_list() { 1243 _free_list.add_as_head(&_secondary_free_list); 1244 } 1245 1246 void append_secondary_free_list_if_not_empty_with_lock() { 1247 // If the secondary free list looks empty there's no reason to 1248 // take the lock and then try to append it. 1249 if (!_secondary_free_list.is_empty()) { 1250 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1251 append_secondary_free_list(); 1252 } 1253 } 1254 1255 void old_set_remove(HeapRegion* hr) { 1256 _old_set.remove(hr); 1257 } 1258 1259 size_t non_young_capacity_bytes() { 1260 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1261 } 1262 1263 void set_free_regions_coming(); 1264 void reset_free_regions_coming(); 1265 bool free_regions_coming() { return _free_regions_coming; } 1266 void wait_while_free_regions_coming(); 1267 1268 // Determine whether the given region is one that we are using as an 1269 // old GC alloc region. 1270 bool is_old_gc_alloc_region(HeapRegion* hr) { 1271 return hr == _retained_old_gc_alloc_region; 1272 } 1273 1274 // Perform a collection of the heap; intended for use in implementing 1275 // "System.gc". This probably implies as full a collection as the 1276 // "CollectedHeap" supports. 1277 virtual void collect(GCCause::Cause cause); 1278 1279 // The same as above but assume that the caller holds the Heap_lock. 1280 void collect_locked(GCCause::Cause cause); 1281 1282 // True iff a evacuation has failed in the most-recent collection. 1283 bool evacuation_failed() { return _evacuation_failed; } 1284 1285 // It will free a region if it has allocated objects in it that are 1286 // all dead. It calls either free_region() or 1287 // free_humongous_region() depending on the type of the region that 1288 // is passed to it. 1289 void free_region_if_empty(HeapRegion* hr, 1290 size_t* pre_used, 1291 FreeRegionList* free_list, 1292 OldRegionSet* old_proxy_set, 1293 HumongousRegionSet* humongous_proxy_set, 1294 HRRSCleanupTask* hrrs_cleanup_task, 1295 bool par); 1296 1297 // It appends the free list to the master free list and updates the 1298 // master humongous list according to the contents of the proxy 1299 // list. It also adjusts the total used bytes according to pre_used 1300 // (if par is true, it will do so by taking the ParGCRareEvent_lock). 1301 void update_sets_after_freeing_regions(size_t pre_used, 1302 FreeRegionList* free_list, 1303 OldRegionSet* old_proxy_set, 1304 HumongousRegionSet* humongous_proxy_set, 1305 bool par); 1306 1307 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1308 virtual bool is_in(const void* p) const; 1309 1310 // Return "TRUE" iff the given object address is within the collection 1311 // set. 1312 inline bool obj_in_cs(oop obj); 1313 1314 // Return "TRUE" iff the given object address is in the reserved 1315 // region of g1. 1316 bool is_in_g1_reserved(const void* p) const { 1317 return _g1_reserved.contains(p); 1318 } 1319 1320 // Returns a MemRegion that corresponds to the space that has been 1321 // reserved for the heap 1322 MemRegion g1_reserved() { 1323 return _g1_reserved; 1324 } 1325 1326 // Returns a MemRegion that corresponds to the space that has been 1327 // committed in the heap 1328 MemRegion g1_committed() { 1329 return _g1_committed; 1330 } 1331 1332 virtual bool is_in_closed_subset(const void* p) const; 1333 1334 // This resets the card table to all zeros. It is used after 1335 // a collection pause which used the card table to claim cards. 1336 void cleanUpCardTable(); 1337 1338 // Iteration functions. 1339 1340 // Iterate over all the ref-containing fields of all objects, calling 1341 // "cl.do_oop" on each. 1342 virtual void oop_iterate(ExtendedOopClosure* cl); 1343 1344 // Same as above, restricted to a memory region. 1345 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl); 1346 1347 // Iterate over all objects, calling "cl.do_object" on each. 1348 virtual void object_iterate(ObjectClosure* cl); 1349 1350 virtual void safe_object_iterate(ObjectClosure* cl) { 1351 object_iterate(cl); 1352 } 1353 1354 // Iterate over all objects allocated since the last collection, calling 1355 // "cl.do_object" on each. The heap must have been initialized properly 1356 // to support this function, or else this call will fail. 1357 virtual void object_iterate_since_last_GC(ObjectClosure* cl); 1358 1359 // Iterate over all spaces in use in the heap, in ascending address order. 1360 virtual void space_iterate(SpaceClosure* cl); 1361 1362 // Iterate over heap regions, in address order, terminating the 1363 // iteration early if the "doHeapRegion" method returns "true". 1364 void heap_region_iterate(HeapRegionClosure* blk) const; 1365 1366 // Return the region with the given index. It assumes the index is valid. 1367 HeapRegion* region_at(uint index) const { return _hrs.at(index); } 1368 1369 // Divide the heap region sequence into "chunks" of some size (the number 1370 // of regions divided by the number of parallel threads times some 1371 // overpartition factor, currently 4). Assumes that this will be called 1372 // in parallel by ParallelGCThreads worker threads with discinct worker 1373 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel 1374 // calls will use the same "claim_value", and that that claim value is 1375 // different from the claim_value of any heap region before the start of 1376 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by 1377 // attempting to claim the first region in each chunk, and, if 1378 // successful, applying the closure to each region in the chunk (and 1379 // setting the claim value of the second and subsequent regions of the 1380 // chunk.) For now requires that "doHeapRegion" always returns "false", 1381 // i.e., that a closure never attempt to abort a traversal. 1382 void heap_region_par_iterate_chunked(HeapRegionClosure* blk, 1383 uint worker, 1384 uint no_of_par_workers, 1385 jint claim_value); 1386 1387 // It resets all the region claim values to the default. 1388 void reset_heap_region_claim_values(); 1389 1390 // Resets the claim values of regions in the current 1391 // collection set to the default. 1392 void reset_cset_heap_region_claim_values(); 1393 1394 #ifdef ASSERT 1395 bool check_heap_region_claim_values(jint claim_value); 1396 1397 // Same as the routine above but only checks regions in the 1398 // current collection set. 1399 bool check_cset_heap_region_claim_values(jint claim_value); 1400 #endif // ASSERT 1401 1402 // Clear the cached cset start regions and (more importantly) 1403 // the time stamps. Called when we reset the GC time stamp. 1404 void clear_cset_start_regions(); 1405 1406 // Given the id of a worker, obtain or calculate a suitable 1407 // starting region for iterating over the current collection set. 1408 HeapRegion* start_cset_region_for_worker(int worker_i); 1409 1410 // This is a convenience method that is used by the 1411 // HeapRegionIterator classes to calculate the starting region for 1412 // each worker so that they do not all start from the same region. 1413 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers); 1414 1415 // Iterate over the regions (if any) in the current collection set. 1416 void collection_set_iterate(HeapRegionClosure* blk); 1417 1418 // As above but starting from region r 1419 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1420 1421 // Returns the first (lowest address) compactible space in the heap. 1422 virtual CompactibleSpace* first_compactible_space(); 1423 1424 // A CollectedHeap will contain some number of spaces. This finds the 1425 // space containing a given address, or else returns NULL. 1426 virtual Space* space_containing(const void* addr) const; 1427 1428 // A G1CollectedHeap will contain some number of heap regions. This 1429 // finds the region containing a given address, or else returns NULL. 1430 template <class T> 1431 inline HeapRegion* heap_region_containing(const T addr) const; 1432 1433 // Like the above, but requires "addr" to be in the heap (to avoid a 1434 // null-check), and unlike the above, may return an continuing humongous 1435 // region. 1436 template <class T> 1437 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1438 1439 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1440 // each address in the (reserved) heap is a member of exactly 1441 // one block. The defining characteristic of a block is that it is 1442 // possible to find its size, and thus to progress forward to the next 1443 // block. (Blocks may be of different sizes.) Thus, blocks may 1444 // represent Java objects, or they might be free blocks in a 1445 // free-list-based heap (or subheap), as long as the two kinds are 1446 // distinguishable and the size of each is determinable. 1447 1448 // Returns the address of the start of the "block" that contains the 1449 // address "addr". We say "blocks" instead of "object" since some heaps 1450 // may not pack objects densely; a chunk may either be an object or a 1451 // non-object. 1452 virtual HeapWord* block_start(const void* addr) const; 1453 1454 // Requires "addr" to be the start of a chunk, and returns its size. 1455 // "addr + size" is required to be the start of a new chunk, or the end 1456 // of the active area of the heap. 1457 virtual size_t block_size(const HeapWord* addr) const; 1458 1459 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1460 // the block is an object. 1461 virtual bool block_is_obj(const HeapWord* addr) const; 1462 1463 // Does this heap support heap inspection? (+PrintClassHistogram) 1464 virtual bool supports_heap_inspection() const { return true; } 1465 1466 // Section on thread-local allocation buffers (TLABs) 1467 // See CollectedHeap for semantics. 1468 1469 virtual bool supports_tlab_allocation() const; 1470 virtual size_t tlab_capacity(Thread* thr) const; 1471 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const; 1472 1473 // Can a compiler initialize a new object without store barriers? 1474 // This permission only extends from the creation of a new object 1475 // via a TLAB up to the first subsequent safepoint. If such permission 1476 // is granted for this heap type, the compiler promises to call 1477 // defer_store_barrier() below on any slow path allocation of 1478 // a new object for which such initializing store barriers will 1479 // have been elided. G1, like CMS, allows this, but should be 1480 // ready to provide a compensating write barrier as necessary 1481 // if that storage came out of a non-young region. The efficiency 1482 // of this implementation depends crucially on being able to 1483 // answer very efficiently in constant time whether a piece of 1484 // storage in the heap comes from a young region or not. 1485 // See ReduceInitialCardMarks. 1486 virtual bool can_elide_tlab_store_barriers() const { 1487 return true; 1488 } 1489 1490 virtual bool card_mark_must_follow_store() const { 1491 return true; 1492 } 1493 1494 bool is_in_young(const oop obj) { 1495 HeapRegion* hr = heap_region_containing(obj); 1496 return hr != NULL && hr->is_young(); 1497 } 1498 1499 #ifdef ASSERT 1500 virtual bool is_in_partial_collection(const void* p); 1501 #endif 1502 1503 virtual bool is_scavengable(const void* addr); 1504 1505 // We don't need barriers for initializing stores to objects 1506 // in the young gen: for the SATB pre-barrier, there is no 1507 // pre-value that needs to be remembered; for the remembered-set 1508 // update logging post-barrier, we don't maintain remembered set 1509 // information for young gen objects. 1510 virtual bool can_elide_initializing_store_barrier(oop new_obj) { 1511 return is_in_young(new_obj); 1512 } 1513 1514 // Returns "true" iff the given word_size is "very large". 1515 static bool isHumongous(size_t word_size) { 1516 // Note this has to be strictly greater-than as the TLABs 1517 // are capped at the humongous thresold and we want to 1518 // ensure that we don't try to allocate a TLAB as 1519 // humongous and that we don't allocate a humongous 1520 // object in a TLAB. 1521 return word_size > _humongous_object_threshold_in_words; 1522 } 1523 1524 // Update mod union table with the set of dirty cards. 1525 void updateModUnion(); 1526 1527 // Set the mod union bits corresponding to the given memRegion. Note 1528 // that this is always a safe operation, since it doesn't clear any 1529 // bits. 1530 void markModUnionRange(MemRegion mr); 1531 1532 // Records the fact that a marking phase is no longer in progress. 1533 void set_marking_complete() { 1534 _mark_in_progress = false; 1535 } 1536 void set_marking_started() { 1537 _mark_in_progress = true; 1538 } 1539 bool mark_in_progress() { 1540 return _mark_in_progress; 1541 } 1542 1543 // Print the maximum heap capacity. 1544 virtual size_t max_capacity() const; 1545 1546 virtual jlong millis_since_last_gc(); 1547 1548 // Perform any cleanup actions necessary before allowing a verification. 1549 virtual void prepare_for_verify(); 1550 1551 // Perform verification. 1552 1553 // vo == UsePrevMarking -> use "prev" marking information, 1554 // vo == UseNextMarking -> use "next" marking information 1555 // vo == UseMarkWord -> use the mark word in the object header 1556 // 1557 // NOTE: Only the "prev" marking information is guaranteed to be 1558 // consistent most of the time, so most calls to this should use 1559 // vo == UsePrevMarking. 1560 // Currently, there is only one case where this is called with 1561 // vo == UseNextMarking, which is to verify the "next" marking 1562 // information at the end of remark. 1563 // Currently there is only one place where this is called with 1564 // vo == UseMarkWord, which is to verify the marking during a 1565 // full GC. 1566 void verify(bool silent, VerifyOption vo); 1567 1568 // Override; it uses the "prev" marking information 1569 virtual void verify(bool silent); 1570 virtual void print_on(outputStream* st) const; 1571 virtual void print_extended_on(outputStream* st) const; 1572 1573 virtual void print_gc_threads_on(outputStream* st) const; 1574 virtual void gc_threads_do(ThreadClosure* tc) const; 1575 1576 // Override 1577 void print_tracing_info() const; 1578 1579 // The following two methods are helpful for debugging RSet issues. 1580 void print_cset_rsets() PRODUCT_RETURN; 1581 void print_all_rsets() PRODUCT_RETURN; 1582 1583 // Convenience function to be used in situations where the heap type can be 1584 // asserted to be this type. 1585 static G1CollectedHeap* heap(); 1586 1587 void set_region_short_lived_locked(HeapRegion* hr); 1588 // add appropriate methods for any other surv rate groups 1589 1590 YoungList* young_list() { return _young_list; } 1591 1592 // debugging 1593 bool check_young_list_well_formed() { 1594 return _young_list->check_list_well_formed(); 1595 } 1596 1597 bool check_young_list_empty(bool check_heap, 1598 bool check_sample = true); 1599 1600 // *** Stuff related to concurrent marking. It's not clear to me that so 1601 // many of these need to be public. 1602 1603 // The functions below are helper functions that a subclass of 1604 // "CollectedHeap" can use in the implementation of its virtual 1605 // functions. 1606 // This performs a concurrent marking of the live objects in a 1607 // bitmap off to the side. 1608 void doConcurrentMark(); 1609 1610 bool isMarkedPrev(oop obj) const; 1611 bool isMarkedNext(oop obj) const; 1612 1613 // Determine if an object is dead, given the object and also 1614 // the region to which the object belongs. An object is dead 1615 // iff a) it was not allocated since the last mark and b) it 1616 // is not marked. 1617 1618 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1619 return 1620 !hr->obj_allocated_since_prev_marking(obj) && 1621 !isMarkedPrev(obj); 1622 } 1623 1624 // This function returns true when an object has been 1625 // around since the previous marking and hasn't yet 1626 // been marked during this marking. 1627 1628 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1629 return 1630 !hr->obj_allocated_since_next_marking(obj) && 1631 !isMarkedNext(obj); 1632 } 1633 1634 // Determine if an object is dead, given only the object itself. 1635 // This will find the region to which the object belongs and 1636 // then call the region version of the same function. 1637 1638 // Added if it is NULL it isn't dead. 1639 1640 bool is_obj_dead(const oop obj) const { 1641 const HeapRegion* hr = heap_region_containing(obj); 1642 if (hr == NULL) { 1643 if (obj == NULL) return false; 1644 else return true; 1645 } 1646 else return is_obj_dead(obj, hr); 1647 } 1648 1649 bool is_obj_ill(const oop obj) const { 1650 const HeapRegion* hr = heap_region_containing(obj); 1651 if (hr == NULL) { 1652 if (obj == NULL) return false; 1653 else return true; 1654 } 1655 else return is_obj_ill(obj, hr); 1656 } 1657 1658 // The methods below are here for convenience and dispatch the 1659 // appropriate method depending on value of the given VerifyOption 1660 // parameter. The options for that parameter are: 1661 // 1662 // vo == UsePrevMarking -> use "prev" marking information, 1663 // vo == UseNextMarking -> use "next" marking information, 1664 // vo == UseMarkWord -> use mark word from object header 1665 1666 bool is_obj_dead_cond(const oop obj, 1667 const HeapRegion* hr, 1668 const VerifyOption vo) const { 1669 switch (vo) { 1670 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 1671 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 1672 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 1673 default: ShouldNotReachHere(); 1674 } 1675 return false; // keep some compilers happy 1676 } 1677 1678 bool is_obj_dead_cond(const oop obj, 1679 const VerifyOption vo) const { 1680 switch (vo) { 1681 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 1682 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 1683 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 1684 default: ShouldNotReachHere(); 1685 } 1686 return false; // keep some compilers happy 1687 } 1688 1689 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1690 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1691 bool is_marked(oop obj, VerifyOption vo); 1692 const char* top_at_mark_start_str(VerifyOption vo); 1693 1694 // The following is just to alert the verification code 1695 // that a full collection has occurred and that the 1696 // remembered sets are no longer up to date. 1697 bool _full_collection; 1698 void set_full_collection() { _full_collection = true;} 1699 void clear_full_collection() {_full_collection = false;} 1700 bool full_collection() {return _full_collection;} 1701 1702 ConcurrentMark* concurrent_mark() const { return _cm; } 1703 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1704 1705 // The dirty cards region list is used to record a subset of regions 1706 // whose cards need clearing. The list if populated during the 1707 // remembered set scanning and drained during the card table 1708 // cleanup. Although the methods are reentrant, population/draining 1709 // phases must not overlap. For synchronization purposes the last 1710 // element on the list points to itself. 1711 HeapRegion* _dirty_cards_region_list; 1712 void push_dirty_cards_region(HeapRegion* hr); 1713 HeapRegion* pop_dirty_cards_region(); 1714 1715 public: 1716 void stop_conc_gc_threads(); 1717 1718 size_t pending_card_num(); 1719 size_t cards_scanned(); 1720 1721 protected: 1722 size_t _max_heap_capacity; 1723 }; 1724 1725 class G1ParGCAllocBuffer: public ParGCAllocBuffer { 1726 private: 1727 bool _retired; 1728 1729 public: 1730 G1ParGCAllocBuffer(size_t gclab_word_size); 1731 1732 void set_buf(HeapWord* buf) { 1733 ParGCAllocBuffer::set_buf(buf); 1734 _retired = false; 1735 } 1736 1737 void retire(bool end_of_gc, bool retain) { 1738 if (_retired) 1739 return; 1740 ParGCAllocBuffer::retire(end_of_gc, retain); 1741 _retired = true; 1742 } 1743 }; 1744 1745 class G1ParScanThreadState : public StackObj { 1746 protected: 1747 G1CollectedHeap* _g1h; 1748 RefToScanQueue* _refs; 1749 DirtyCardQueue _dcq; 1750 CardTableModRefBS* _ct_bs; 1751 G1RemSet* _g1_rem; 1752 1753 G1ParGCAllocBuffer _surviving_alloc_buffer; 1754 G1ParGCAllocBuffer _tenured_alloc_buffer; 1755 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount]; 1756 ageTable _age_table; 1757 1758 size_t _alloc_buffer_waste; 1759 size_t _undo_waste; 1760 1761 OopsInHeapRegionClosure* _evac_failure_cl; 1762 G1ParScanHeapEvacClosure* _evac_cl; 1763 G1ParScanPartialArrayClosure* _partial_scan_cl; 1764 1765 int _hash_seed; 1766 uint _queue_num; 1767 1768 size_t _term_attempts; 1769 1770 double _start; 1771 double _start_strong_roots; 1772 double _strong_roots_time; 1773 double _start_term; 1774 double _term_time; 1775 1776 // Map from young-age-index (0 == not young, 1 is youngest) to 1777 // surviving words. base is what we get back from the malloc call 1778 size_t* _surviving_young_words_base; 1779 // this points into the array, as we use the first few entries for padding 1780 size_t* _surviving_young_words; 1781 1782 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t)) 1783 1784 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; } 1785 1786 void add_to_undo_waste(size_t waste) { _undo_waste += waste; } 1787 1788 DirtyCardQueue& dirty_card_queue() { return _dcq; } 1789 CardTableModRefBS* ctbs() { return _ct_bs; } 1790 1791 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) { 1792 if (!from->is_survivor()) { 1793 _g1_rem->par_write_ref(from, p, tid); 1794 } 1795 } 1796 1797 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) { 1798 // If the new value of the field points to the same region or 1799 // is the to-space, we don't need to include it in the Rset updates. 1800 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) { 1801 size_t card_index = ctbs()->index_for(p); 1802 // If the card hasn't been added to the buffer, do it. 1803 if (ctbs()->mark_card_deferred(card_index)) { 1804 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index)); 1805 } 1806 } 1807 } 1808 1809 public: 1810 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num); 1811 1812 ~G1ParScanThreadState() { 1813 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC); 1814 } 1815 1816 RefToScanQueue* refs() { return _refs; } 1817 ageTable* age_table() { return &_age_table; } 1818 1819 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) { 1820 return _alloc_buffers[purpose]; 1821 } 1822 1823 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; } 1824 size_t undo_waste() const { return _undo_waste; } 1825 1826 #ifdef ASSERT 1827 bool verify_ref(narrowOop* ref) const; 1828 bool verify_ref(oop* ref) const; 1829 bool verify_task(StarTask ref) const; 1830 #endif // ASSERT 1831 1832 template <class T> void push_on_queue(T* ref) { 1833 assert(verify_ref(ref), "sanity"); 1834 refs()->push(ref); 1835 } 1836 1837 template <class T> void update_rs(HeapRegion* from, T* p, int tid) { 1838 if (G1DeferredRSUpdate) { 1839 deferred_rs_update(from, p, tid); 1840 } else { 1841 immediate_rs_update(from, p, tid); 1842 } 1843 } 1844 1845 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) { 1846 HeapWord* obj = NULL; 1847 size_t gclab_word_size = _g1h->desired_plab_sz(purpose); 1848 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) { 1849 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose); 1850 add_to_alloc_buffer_waste(alloc_buf->words_remaining()); 1851 alloc_buf->flush_stats_and_retire(_g1h->stats_for_purpose(purpose), 1852 false /* end_of_gc */, 1853 false /* retain */); 1854 1855 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size); 1856 if (buf == NULL) return NULL; // Let caller handle allocation failure. 1857 // Otherwise. 1858 alloc_buf->set_word_size(gclab_word_size); 1859 alloc_buf->set_buf(buf); 1860 1861 obj = alloc_buf->allocate(word_sz); 1862 assert(obj != NULL, "buffer was definitely big enough..."); 1863 } else { 1864 obj = _g1h->par_allocate_during_gc(purpose, word_sz); 1865 } 1866 return obj; 1867 } 1868 1869 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) { 1870 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz); 1871 if (obj != NULL) return obj; 1872 return allocate_slow(purpose, word_sz); 1873 } 1874 1875 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) { 1876 if (alloc_buffer(purpose)->contains(obj)) { 1877 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1), 1878 "should contain whole object"); 1879 alloc_buffer(purpose)->undo_allocation(obj, word_sz); 1880 } else { 1881 CollectedHeap::fill_with_object(obj, word_sz); 1882 add_to_undo_waste(word_sz); 1883 } 1884 } 1885 1886 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) { 1887 _evac_failure_cl = evac_failure_cl; 1888 } 1889 OopsInHeapRegionClosure* evac_failure_closure() { 1890 return _evac_failure_cl; 1891 } 1892 1893 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) { 1894 _evac_cl = evac_cl; 1895 } 1896 1897 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) { 1898 _partial_scan_cl = partial_scan_cl; 1899 } 1900 1901 int* hash_seed() { return &_hash_seed; } 1902 uint queue_num() { return _queue_num; } 1903 1904 size_t term_attempts() const { return _term_attempts; } 1905 void note_term_attempt() { _term_attempts++; } 1906 1907 void start_strong_roots() { 1908 _start_strong_roots = os::elapsedTime(); 1909 } 1910 void end_strong_roots() { 1911 _strong_roots_time += (os::elapsedTime() - _start_strong_roots); 1912 } 1913 double strong_roots_time() const { return _strong_roots_time; } 1914 1915 void start_term_time() { 1916 note_term_attempt(); 1917 _start_term = os::elapsedTime(); 1918 } 1919 void end_term_time() { 1920 _term_time += (os::elapsedTime() - _start_term); 1921 } 1922 double term_time() const { return _term_time; } 1923 1924 double elapsed_time() const { 1925 return os::elapsedTime() - _start; 1926 } 1927 1928 static void 1929 print_termination_stats_hdr(outputStream* const st = gclog_or_tty); 1930 void 1931 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const; 1932 1933 size_t* surviving_young_words() { 1934 // We add on to hide entry 0 which accumulates surviving words for 1935 // age -1 regions (i.e. non-young ones) 1936 return _surviving_young_words; 1937 } 1938 1939 void retire_alloc_buffers() { 1940 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) { 1941 size_t waste = _alloc_buffers[ap]->words_remaining(); 1942 add_to_alloc_buffer_waste(waste); 1943 _alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap), 1944 true /* end_of_gc */, 1945 false /* retain */); 1946 } 1947 } 1948 1949 template <class T> void deal_with_reference(T* ref_to_scan) { 1950 if (has_partial_array_mask(ref_to_scan)) { 1951 _partial_scan_cl->do_oop_nv(ref_to_scan); 1952 } else { 1953 // Note: we can use "raw" versions of "region_containing" because 1954 // "obj_to_scan" is definitely in the heap, and is not in a 1955 // humongous region. 1956 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan); 1957 _evac_cl->set_region(r); 1958 _evac_cl->do_oop_nv(ref_to_scan); 1959 } 1960 } 1961 1962 void deal_with_reference(StarTask ref) { 1963 assert(verify_task(ref), "sanity"); 1964 if (ref.is_narrow()) { 1965 deal_with_reference((narrowOop*)ref); 1966 } else { 1967 deal_with_reference((oop*)ref); 1968 } 1969 } 1970 1971 public: 1972 void trim_queue(); 1973 }; 1974 1975 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP