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(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 // Ensure that no further allocations can happen in "r", bearing in mind 594 // that parallel threads might be attempting allocations. 595 void par_allocate_remaining_space(HeapRegion* r); 596 597 // Allocation attempt during GC for a survivor object / PLAB. 598 inline HeapWord* survivor_attempt_allocation(size_t word_size); 599 600 // Allocation attempt during GC for an old object / PLAB. 601 inline HeapWord* old_attempt_allocation(size_t word_size); 602 603 // These methods are the "callbacks" from the G1AllocRegion class. 604 605 // For mutator alloc regions. 606 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 607 void retire_mutator_alloc_region(HeapRegion* alloc_region, 608 size_t allocated_bytes); 609 610 // For GC alloc regions. 611 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 612 GCAllocPurpose ap); 613 void retire_gc_alloc_region(HeapRegion* alloc_region, 614 size_t allocated_bytes, GCAllocPurpose ap); 615 616 // - if explicit_gc is true, the GC is for a System.gc() or a heap 617 // inspection request and should collect the entire heap 618 // - if clear_all_soft_refs is true, all soft references should be 619 // cleared during the GC 620 // - if explicit_gc is false, word_size describes the allocation that 621 // the GC should attempt (at least) to satisfy 622 // - it returns false if it is unable to do the collection due to the 623 // GC locker being active, true otherwise 624 bool do_collection(bool explicit_gc, 625 bool clear_all_soft_refs, 626 size_t word_size); 627 628 // Callback from VM_G1CollectFull operation. 629 // Perform a full collection. 630 virtual void do_full_collection(bool clear_all_soft_refs); 631 632 // Resize the heap if necessary after a full collection. If this is 633 // after a collect-for allocation, "word_size" is the allocation size, 634 // and will be considered part of the used portion of the heap. 635 void resize_if_necessary_after_full_collection(size_t word_size); 636 637 // Callback from VM_G1CollectForAllocation operation. 638 // This function does everything necessary/possible to satisfy a 639 // failed allocation request (including collection, expansion, etc.) 640 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded); 641 642 // Attempting to expand the heap sufficiently 643 // to support an allocation of the given "word_size". If 644 // successful, perform the allocation and return the address of the 645 // allocated block, or else "NULL". 646 HeapWord* expand_and_allocate(size_t word_size); 647 648 // Process any reference objects discovered during 649 // an incremental evacuation pause. 650 void process_discovered_references(uint no_of_gc_workers); 651 652 // Enqueue any remaining discovered references 653 // after processing. 654 void enqueue_discovered_references(uint no_of_gc_workers); 655 656 public: 657 658 G1MonitoringSupport* g1mm() { 659 assert(_g1mm != NULL, "should have been initialized"); 660 return _g1mm; 661 } 662 663 // Expand the garbage-first heap by at least the given size (in bytes!). 664 // Returns true if the heap was expanded by the requested amount; 665 // false otherwise. 666 // (Rounds up to a HeapRegion boundary.) 667 bool expand(size_t expand_bytes); 668 669 // Do anything common to GC's. 670 virtual void gc_prologue(bool full); 671 virtual void gc_epilogue(bool full); 672 673 // We register a region with the fast "in collection set" test. We 674 // simply set to true the array slot corresponding to this region. 675 void register_region_with_in_cset_fast_test(HeapRegion* r) { 676 assert(_in_cset_fast_test_base != NULL, "sanity"); 677 assert(r->in_collection_set(), "invariant"); 678 uint index = r->hrs_index(); 679 assert(index < _in_cset_fast_test_length, "invariant"); 680 assert(!_in_cset_fast_test_base[index], "invariant"); 681 _in_cset_fast_test_base[index] = true; 682 } 683 684 // This is a fast test on whether a reference points into the 685 // collection set or not. It does not assume that the reference 686 // points into the heap; if it doesn't, it will return false. 687 bool in_cset_fast_test(oop obj) { 688 assert(_in_cset_fast_test != NULL, "sanity"); 689 if (_g1_committed.contains((HeapWord*) obj)) { 690 // no need to subtract the bottom of the heap from obj, 691 // _in_cset_fast_test is biased 692 uintx index = (uintx) obj >> HeapRegion::LogOfHRGrainBytes; 693 bool ret = _in_cset_fast_test[index]; 694 // let's make sure the result is consistent with what the slower 695 // test returns 696 assert( ret || !obj_in_cs(obj), "sanity"); 697 assert(!ret || obj_in_cs(obj), "sanity"); 698 return ret; 699 } else { 700 return false; 701 } 702 } 703 704 void clear_cset_fast_test() { 705 assert(_in_cset_fast_test_base != NULL, "sanity"); 706 memset(_in_cset_fast_test_base, false, 707 (size_t) _in_cset_fast_test_length * sizeof(bool)); 708 } 709 710 // This is called at the start of either a concurrent cycle or a Full 711 // GC to update the number of old marking cycles started. 712 void increment_old_marking_cycles_started(); 713 714 // This is called at the end of either a concurrent cycle or a Full 715 // GC to update the number of old marking cycles completed. Those two 716 // can happen in a nested fashion, i.e., we start a concurrent 717 // cycle, a Full GC happens half-way through it which ends first, 718 // and then the cycle notices that a Full GC happened and ends 719 // too. The concurrent parameter is a boolean to help us do a bit 720 // tighter consistency checking in the method. If concurrent is 721 // false, the caller is the inner caller in the nesting (i.e., the 722 // Full GC). If concurrent is true, the caller is the outer caller 723 // in this nesting (i.e., the concurrent cycle). Further nesting is 724 // not currently supported. The end of this call also notifies 725 // the FullGCCount_lock in case a Java thread is waiting for a full 726 // GC to happen (e.g., it called System.gc() with 727 // +ExplicitGCInvokesConcurrent). 728 void increment_old_marking_cycles_completed(bool concurrent); 729 730 unsigned int old_marking_cycles_completed() { 731 return _old_marking_cycles_completed; 732 } 733 734 G1HRPrinter* hr_printer() { return &_hr_printer; } 735 736 protected: 737 738 // Shrink the garbage-first heap by at most the given size (in bytes!). 739 // (Rounds down to a HeapRegion boundary.) 740 virtual void shrink(size_t expand_bytes); 741 void shrink_helper(size_t expand_bytes); 742 743 #if TASKQUEUE_STATS 744 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 745 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 746 void reset_taskqueue_stats(); 747 #endif // TASKQUEUE_STATS 748 749 // Schedule the VM operation that will do an evacuation pause to 750 // satisfy an allocation request of word_size. *succeeded will 751 // return whether the VM operation was successful (it did do an 752 // evacuation pause) or not (another thread beat us to it or the GC 753 // locker was active). Given that we should not be holding the 754 // Heap_lock when we enter this method, we will pass the 755 // gc_count_before (i.e., total_collections()) as a parameter since 756 // it has to be read while holding the Heap_lock. Currently, both 757 // methods that call do_collection_pause() release the Heap_lock 758 // before the call, so it's easy to read gc_count_before just before. 759 HeapWord* do_collection_pause(size_t word_size, 760 unsigned int gc_count_before, 761 bool* succeeded); 762 763 // The guts of the incremental collection pause, executed by the vm 764 // thread. It returns false if it is unable to do the collection due 765 // to the GC locker being active, true otherwise 766 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 767 768 // Actually do the work of evacuating the collection set. 769 void evacuate_collection_set(); 770 771 // The g1 remembered set of the heap. 772 G1RemSet* _g1_rem_set; 773 // And it's mod ref barrier set, used to track updates for the above. 774 ModRefBarrierSet* _mr_bs; 775 776 // A set of cards that cover the objects for which the Rsets should be updated 777 // concurrently after the collection. 778 DirtyCardQueueSet _dirty_card_queue_set; 779 780 // The Heap Region Rem Set Iterator. 781 HeapRegionRemSetIterator** _rem_set_iterator; 782 783 // The closure used to refine a single card. 784 RefineCardTableEntryClosure* _refine_cte_cl; 785 786 // A function to check the consistency of dirty card logs. 787 void check_ct_logs_at_safepoint(); 788 789 // A DirtyCardQueueSet that is used to hold cards that contain 790 // references into the current collection set. This is used to 791 // update the remembered sets of the regions in the collection 792 // set in the event of an evacuation failure. 793 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 794 795 // After a collection pause, make the regions in the CS into free 796 // regions. 797 void free_collection_set(HeapRegion* cs_head); 798 799 // Abandon the current collection set without recording policy 800 // statistics or updating free lists. 801 void abandon_collection_set(HeapRegion* cs_head); 802 803 // Applies "scan_non_heap_roots" to roots outside the heap, 804 // "scan_rs" to roots inside the heap (having done "set_region" to 805 // indicate the region in which the root resides), 806 // and does "scan_metadata" If "scan_rs" is 807 // NULL, then this step is skipped. The "worker_i" 808 // param is for use with parallel roots processing, and should be 809 // the "i" of the calling parallel worker thread's work(i) function. 810 // In the sequential case this param will be ignored. 811 void g1_process_strong_roots(bool is_scavenging, 812 ScanningOption so, 813 OopClosure* scan_non_heap_roots, 814 OopsInHeapRegionClosure* scan_rs, 815 G1KlassScanClosure* scan_klasses, 816 int worker_i); 817 818 // Apply "blk" to all the weak roots of the system. These include 819 // JNI weak roots, the code cache, system dictionary, symbol table, 820 // string table, and referents of reachable weak refs. 821 void g1_process_weak_roots(OopClosure* root_closure, 822 OopClosure* non_root_closure); 823 824 // Frees a non-humongous region by initializing its contents and 825 // adding it to the free list that's passed as a parameter (this is 826 // usually a local list which will be appended to the master free 827 // list later). The used bytes of freed regions are accumulated in 828 // pre_used. If par is true, the region's RSet will not be freed 829 // up. The assumption is that this will be done later. 830 void free_region(HeapRegion* hr, 831 size_t* pre_used, 832 FreeRegionList* free_list, 833 bool par); 834 835 // Frees a humongous region by collapsing it into individual regions 836 // and calling free_region() for each of them. The freed regions 837 // will be added to the free list that's passed as a parameter (this 838 // is usually a local list which will be appended to the master free 839 // list later). The used bytes of freed regions are accumulated in 840 // pre_used. If par is true, the region's RSet will not be freed 841 // up. The assumption is that this will be done later. 842 void free_humongous_region(HeapRegion* hr, 843 size_t* pre_used, 844 FreeRegionList* free_list, 845 HumongousRegionSet* humongous_proxy_set, 846 bool par); 847 848 // Notifies all the necessary spaces that the committed space has 849 // been updated (either expanded or shrunk). It should be called 850 // after _g1_storage is updated. 851 void update_committed_space(HeapWord* old_end, HeapWord* new_end); 852 853 // The concurrent marker (and the thread it runs in.) 854 ConcurrentMark* _cm; 855 ConcurrentMarkThread* _cmThread; 856 bool _mark_in_progress; 857 858 // The concurrent refiner. 859 ConcurrentG1Refine* _cg1r; 860 861 // The parallel task queues 862 RefToScanQueueSet *_task_queues; 863 864 // True iff a evacuation has failed in the current collection. 865 bool _evacuation_failed; 866 867 // Set the attribute indicating whether evacuation has failed in the 868 // current collection. 869 void set_evacuation_failed(bool b) { _evacuation_failed = b; } 870 871 // Failed evacuations cause some logical from-space objects to have 872 // forwarding pointers to themselves. Reset them. 873 void remove_self_forwarding_pointers(); 874 875 // When one is non-null, so is the other. Together, they each pair is 876 // an object with a preserved mark, and its mark value. 877 GrowableArray<oop>* _objs_with_preserved_marks; 878 GrowableArray<markOop>* _preserved_marks_of_objs; 879 880 // Preserve the mark of "obj", if necessary, in preparation for its mark 881 // word being overwritten with a self-forwarding-pointer. 882 void preserve_mark_if_necessary(oop obj, markOop m); 883 884 // The stack of evac-failure objects left to be scanned. 885 GrowableArray<oop>* _evac_failure_scan_stack; 886 // The closure to apply to evac-failure objects. 887 888 OopsInHeapRegionClosure* _evac_failure_closure; 889 // Set the field above. 890 void 891 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) { 892 _evac_failure_closure = evac_failure_closure; 893 } 894 895 // Push "obj" on the scan stack. 896 void push_on_evac_failure_scan_stack(oop obj); 897 // Process scan stack entries until the stack is empty. 898 void drain_evac_failure_scan_stack(); 899 // True iff an invocation of "drain_scan_stack" is in progress; to 900 // prevent unnecessary recursion. 901 bool _drain_in_progress; 902 903 // Do any necessary initialization for evacuation-failure handling. 904 // "cl" is the closure that will be used to process evac-failure 905 // objects. 906 void init_for_evac_failure(OopsInHeapRegionClosure* cl); 907 // Do any necessary cleanup for evacuation-failure handling data 908 // structures. 909 void finalize_for_evac_failure(); 910 911 // An attempt to evacuate "obj" has failed; take necessary steps. 912 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj); 913 void handle_evacuation_failure_common(oop obj, markOop m); 914 915 #ifndef PRODUCT 916 // Support for forcing evacuation failures. Analogous to 917 // PromotionFailureALot for the other collectors. 918 919 // Records whether G1EvacuationFailureALot should be in effect 920 // for the current GC 921 bool _evacuation_failure_alot_for_current_gc; 922 923 // Used to record the GC number for interval checking when 924 // determining whether G1EvaucationFailureALot is in effect 925 // for the current GC. 926 size_t _evacuation_failure_alot_gc_number; 927 928 // Count of the number of evacuations between failures. 929 volatile size_t _evacuation_failure_alot_count; 930 931 // Set whether G1EvacuationFailureALot should be in effect 932 // for the current GC (based upon the type of GC and which 933 // command line flags are set); 934 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 935 bool during_initial_mark, 936 bool during_marking); 937 938 inline void set_evacuation_failure_alot_for_current_gc(); 939 940 // Return true if it's time to cause an evacuation failure. 941 inline bool evacuation_should_fail(); 942 943 // Reset the G1EvacuationFailureALot counters. Should be called at 944 // the end of an evacuation pause in which an evacuation failure ocurred. 945 inline void reset_evacuation_should_fail(); 946 #endif // !PRODUCT 947 948 // ("Weak") Reference processing support. 949 // 950 // G1 has 2 instances of the referece processor class. One 951 // (_ref_processor_cm) handles reference object discovery 952 // and subsequent processing during concurrent marking cycles. 953 // 954 // The other (_ref_processor_stw) handles reference object 955 // discovery and processing during full GCs and incremental 956 // evacuation pauses. 957 // 958 // During an incremental pause, reference discovery will be 959 // temporarily disabled for _ref_processor_cm and will be 960 // enabled for _ref_processor_stw. At the end of the evacuation 961 // pause references discovered by _ref_processor_stw will be 962 // processed and discovery will be disabled. The previous 963 // setting for reference object discovery for _ref_processor_cm 964 // will be re-instated. 965 // 966 // At the start of marking: 967 // * Discovery by the CM ref processor is verified to be inactive 968 // and it's discovered lists are empty. 969 // * Discovery by the CM ref processor is then enabled. 970 // 971 // At the end of marking: 972 // * Any references on the CM ref processor's discovered 973 // lists are processed (possibly MT). 974 // 975 // At the start of full GC we: 976 // * Disable discovery by the CM ref processor and 977 // empty CM ref processor's discovered lists 978 // (without processing any entries). 979 // * Verify that the STW ref processor is inactive and it's 980 // discovered lists are empty. 981 // * Temporarily set STW ref processor discovery as single threaded. 982 // * Temporarily clear the STW ref processor's _is_alive_non_header 983 // field. 984 // * Finally enable discovery by the STW ref processor. 985 // 986 // The STW ref processor is used to record any discovered 987 // references during the full GC. 988 // 989 // At the end of a full GC we: 990 // * Enqueue any reference objects discovered by the STW ref processor 991 // that have non-live referents. This has the side-effect of 992 // making the STW ref processor inactive by disabling discovery. 993 // * Verify that the CM ref processor is still inactive 994 // and no references have been placed on it's discovered 995 // lists (also checked as a precondition during initial marking). 996 997 // The (stw) reference processor... 998 ReferenceProcessor* _ref_processor_stw; 999 1000 // During reference object discovery, the _is_alive_non_header 1001 // closure (if non-null) is applied to the referent object to 1002 // determine whether the referent is live. If so then the 1003 // reference object does not need to be 'discovered' and can 1004 // be treated as a regular oop. This has the benefit of reducing 1005 // the number of 'discovered' reference objects that need to 1006 // be processed. 1007 // 1008 // Instance of the is_alive closure for embedding into the 1009 // STW reference processor as the _is_alive_non_header field. 1010 // Supplying a value for the _is_alive_non_header field is 1011 // optional but doing so prevents unnecessary additions to 1012 // the discovered lists during reference discovery. 1013 G1STWIsAliveClosure _is_alive_closure_stw; 1014 1015 // The (concurrent marking) reference processor... 1016 ReferenceProcessor* _ref_processor_cm; 1017 1018 // Instance of the concurrent mark is_alive closure for embedding 1019 // into the Concurrent Marking reference processor as the 1020 // _is_alive_non_header field. Supplying a value for the 1021 // _is_alive_non_header field is optional but doing so prevents 1022 // unnecessary additions to the discovered lists during reference 1023 // discovery. 1024 G1CMIsAliveClosure _is_alive_closure_cm; 1025 1026 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 1027 HeapRegion** _worker_cset_start_region; 1028 1029 // Time stamp to validate the regions recorded in the cache 1030 // used by G1CollectedHeap::start_cset_region_for_worker(). 1031 // The heap region entry for a given worker is valid iff 1032 // the associated time stamp value matches the current value 1033 // of G1CollectedHeap::_gc_time_stamp. 1034 unsigned int* _worker_cset_start_region_time_stamp; 1035 1036 enum G1H_process_strong_roots_tasks { 1037 G1H_PS_filter_satb_buffers, 1038 G1H_PS_refProcessor_oops_do, 1039 // Leave this one last. 1040 G1H_PS_NumElements 1041 }; 1042 1043 SubTasksDone* _process_strong_tasks; 1044 1045 volatile bool _free_regions_coming; 1046 1047 public: 1048 1049 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; } 1050 1051 void set_refine_cte_cl_concurrency(bool concurrent); 1052 1053 RefToScanQueue *task_queue(int i) const; 1054 1055 // A set of cards where updates happened during the GC 1056 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 1057 1058 // A DirtyCardQueueSet that is used to hold cards that contain 1059 // references into the current collection set. This is used to 1060 // update the remembered sets of the regions in the collection 1061 // set in the event of an evacuation failure. 1062 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 1063 { return _into_cset_dirty_card_queue_set; } 1064 1065 // Create a G1CollectedHeap with the specified policy. 1066 // Must call the initialize method afterwards. 1067 // May not return if something goes wrong. 1068 G1CollectedHeap(G1CollectorPolicy* policy); 1069 1070 // Initialize the G1CollectedHeap to have the initial and 1071 // maximum sizes and remembered and barrier sets 1072 // specified by the policy object. 1073 jint initialize(); 1074 1075 // Initialize weak reference processing. 1076 virtual void ref_processing_init(); 1077 1078 void set_par_threads(uint t) { 1079 SharedHeap::set_par_threads(t); 1080 // Done in SharedHeap but oddly there are 1081 // two _process_strong_tasks's in a G1CollectedHeap 1082 // so do it here too. 1083 _process_strong_tasks->set_n_threads(t); 1084 } 1085 1086 // Set _n_par_threads according to a policy TBD. 1087 void set_par_threads(); 1088 1089 void set_n_termination(int t) { 1090 _process_strong_tasks->set_n_threads(t); 1091 } 1092 1093 virtual CollectedHeap::Name kind() const { 1094 return CollectedHeap::G1CollectedHeap; 1095 } 1096 1097 // The current policy object for the collector. 1098 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1099 1100 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } 1101 1102 // Adaptive size policy. No such thing for g1. 1103 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1104 1105 // The rem set and barrier set. 1106 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1107 ModRefBarrierSet* mr_bs() const { return _mr_bs; } 1108 1109 // The rem set iterator. 1110 HeapRegionRemSetIterator* rem_set_iterator(int i) { 1111 return _rem_set_iterator[i]; 1112 } 1113 1114 HeapRegionRemSetIterator* rem_set_iterator() { 1115 return _rem_set_iterator[0]; 1116 } 1117 1118 unsigned get_gc_time_stamp() { 1119 return _gc_time_stamp; 1120 } 1121 1122 void reset_gc_time_stamp() { 1123 _gc_time_stamp = 0; 1124 OrderAccess::fence(); 1125 // Clear the cached CSet starting regions and time stamps. 1126 // Their validity is dependent on the GC timestamp. 1127 clear_cset_start_regions(); 1128 } 1129 1130 void check_gc_time_stamps() PRODUCT_RETURN; 1131 1132 void increment_gc_time_stamp() { 1133 ++_gc_time_stamp; 1134 OrderAccess::fence(); 1135 } 1136 1137 // Reset the given region's GC timestamp. If it's starts humongous, 1138 // also reset the GC timestamp of its corresponding 1139 // continues humongous regions too. 1140 void reset_gc_time_stamps(HeapRegion* hr); 1141 1142 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1143 DirtyCardQueue* into_cset_dcq, 1144 bool concurrent, int worker_i); 1145 1146 // The shared block offset table array. 1147 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1148 1149 // Reference Processing accessors 1150 1151 // The STW reference processor.... 1152 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1153 1154 // The Concurent Marking reference processor... 1155 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1156 1157 virtual size_t capacity() const; 1158 virtual size_t used() const; 1159 // This should be called when we're not holding the heap lock. The 1160 // result might be a bit inaccurate. 1161 size_t used_unlocked() const; 1162 size_t recalculate_used() const; 1163 1164 // These virtual functions do the actual allocation. 1165 // Some heaps may offer a contiguous region for shared non-blocking 1166 // allocation, via inlined code (by exporting the address of the top and 1167 // end fields defining the extent of the contiguous allocation region.) 1168 // But G1CollectedHeap doesn't yet support this. 1169 1170 // Return an estimate of the maximum allocation that could be performed 1171 // without triggering any collection or expansion activity. In a 1172 // generational collector, for example, this is probably the largest 1173 // allocation that could be supported (without expansion) in the youngest 1174 // generation. It is "unsafe" because no locks are taken; the result 1175 // should be treated as an approximation, not a guarantee, for use in 1176 // heuristic resizing decisions. 1177 virtual size_t unsafe_max_alloc(); 1178 1179 virtual bool is_maximal_no_gc() const { 1180 return _g1_storage.uncommitted_size() == 0; 1181 } 1182 1183 // The total number of regions in the heap. 1184 uint n_regions() { return _hrs.length(); } 1185 1186 // The max number of regions in the heap. 1187 uint max_regions() { return _hrs.max_length(); } 1188 1189 // The number of regions that are completely free. 1190 uint free_regions() { return _free_list.length(); } 1191 1192 // The number of regions that are not completely free. 1193 uint used_regions() { return n_regions() - free_regions(); } 1194 1195 // The number of regions available for "regular" expansion. 1196 uint expansion_regions() { return _expansion_regions; } 1197 1198 // Factory method for HeapRegion instances. It will return NULL if 1199 // the allocation fails. 1200 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom); 1201 1202 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1203 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1204 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1205 void verify_dirty_young_regions() PRODUCT_RETURN; 1206 1207 // verify_region_sets() performs verification over the region 1208 // lists. It will be compiled in the product code to be used when 1209 // necessary (i.e., during heap verification). 1210 void verify_region_sets(); 1211 1212 // verify_region_sets_optional() is planted in the code for 1213 // list verification in non-product builds (and it can be enabled in 1214 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1). 1215 #if HEAP_REGION_SET_FORCE_VERIFY 1216 void verify_region_sets_optional() { 1217 verify_region_sets(); 1218 } 1219 #else // HEAP_REGION_SET_FORCE_VERIFY 1220 void verify_region_sets_optional() { } 1221 #endif // HEAP_REGION_SET_FORCE_VERIFY 1222 1223 #ifdef ASSERT 1224 bool is_on_master_free_list(HeapRegion* hr) { 1225 return hr->containing_set() == &_free_list; 1226 } 1227 1228 bool is_in_humongous_set(HeapRegion* hr) { 1229 return hr->containing_set() == &_humongous_set; 1230 } 1231 #endif // ASSERT 1232 1233 // Wrapper for the region list operations that can be called from 1234 // methods outside this class. 1235 1236 void secondary_free_list_add_as_tail(FreeRegionList* list) { 1237 _secondary_free_list.add_as_tail(list); 1238 } 1239 1240 void append_secondary_free_list() { 1241 _free_list.add_as_head(&_secondary_free_list); 1242 } 1243 1244 void append_secondary_free_list_if_not_empty_with_lock() { 1245 // If the secondary free list looks empty there's no reason to 1246 // take the lock and then try to append it. 1247 if (!_secondary_free_list.is_empty()) { 1248 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1249 append_secondary_free_list(); 1250 } 1251 } 1252 1253 void old_set_remove(HeapRegion* hr) { 1254 _old_set.remove(hr); 1255 } 1256 1257 size_t non_young_capacity_bytes() { 1258 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1259 } 1260 1261 void set_free_regions_coming(); 1262 void reset_free_regions_coming(); 1263 bool free_regions_coming() { return _free_regions_coming; } 1264 void wait_while_free_regions_coming(); 1265 1266 // Determine whether the given region is one that we are using as an 1267 // old GC alloc region. 1268 bool is_old_gc_alloc_region(HeapRegion* hr) { 1269 return hr == _retained_old_gc_alloc_region; 1270 } 1271 1272 // Perform a collection of the heap; intended for use in implementing 1273 // "System.gc". This probably implies as full a collection as the 1274 // "CollectedHeap" supports. 1275 virtual void collect(GCCause::Cause cause); 1276 1277 // The same as above but assume that the caller holds the Heap_lock. 1278 void collect_locked(GCCause::Cause cause); 1279 1280 // True iff a evacuation has failed in the most-recent collection. 1281 bool evacuation_failed() { return _evacuation_failed; } 1282 1283 // It will free a region if it has allocated objects in it that are 1284 // all dead. It calls either free_region() or 1285 // free_humongous_region() depending on the type of the region that 1286 // is passed to it. 1287 void free_region_if_empty(HeapRegion* hr, 1288 size_t* pre_used, 1289 FreeRegionList* free_list, 1290 OldRegionSet* old_proxy_set, 1291 HumongousRegionSet* humongous_proxy_set, 1292 HRRSCleanupTask* hrrs_cleanup_task, 1293 bool par); 1294 1295 // It appends the free list to the master free list and updates the 1296 // master humongous list according to the contents of the proxy 1297 // list. It also adjusts the total used bytes according to pre_used 1298 // (if par is true, it will do so by taking the ParGCRareEvent_lock). 1299 void update_sets_after_freeing_regions(size_t pre_used, 1300 FreeRegionList* free_list, 1301 OldRegionSet* old_proxy_set, 1302 HumongousRegionSet* humongous_proxy_set, 1303 bool par); 1304 1305 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1306 virtual bool is_in(const void* p) const; 1307 1308 // Return "TRUE" iff the given object address is within the collection 1309 // set. 1310 inline bool obj_in_cs(oop obj); 1311 1312 // Return "TRUE" iff the given object address is in the reserved 1313 // region of g1. 1314 bool is_in_g1_reserved(const void* p) const { 1315 return _g1_reserved.contains(p); 1316 } 1317 1318 // Returns a MemRegion that corresponds to the space that has been 1319 // reserved for the heap 1320 MemRegion g1_reserved() { 1321 return _g1_reserved; 1322 } 1323 1324 // Returns a MemRegion that corresponds to the space that has been 1325 // committed in the heap 1326 MemRegion g1_committed() { 1327 return _g1_committed; 1328 } 1329 1330 virtual bool is_in_closed_subset(const void* p) const; 1331 1332 // This resets the card table to all zeros. It is used after 1333 // a collection pause which used the card table to claim cards. 1334 void cleanUpCardTable(); 1335 1336 // Iteration functions. 1337 1338 // Iterate over all the ref-containing fields of all objects, calling 1339 // "cl.do_oop" on each. 1340 virtual void oop_iterate(ExtendedOopClosure* cl); 1341 1342 // Same as above, restricted to a memory region. 1343 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl); 1344 1345 // Iterate over all objects, calling "cl.do_object" on each. 1346 virtual void object_iterate(ObjectClosure* cl); 1347 1348 virtual void safe_object_iterate(ObjectClosure* cl) { 1349 object_iterate(cl); 1350 } 1351 1352 // Iterate over all objects allocated since the last collection, calling 1353 // "cl.do_object" on each. The heap must have been initialized properly 1354 // to support this function, or else this call will fail. 1355 virtual void object_iterate_since_last_GC(ObjectClosure* cl); 1356 1357 // Iterate over all spaces in use in the heap, in ascending address order. 1358 virtual void space_iterate(SpaceClosure* cl); 1359 1360 // Iterate over heap regions, in address order, terminating the 1361 // iteration early if the "doHeapRegion" method returns "true". 1362 void heap_region_iterate(HeapRegionClosure* blk) const; 1363 1364 // Return the region with the given index. It assumes the index is valid. 1365 HeapRegion* region_at(uint index) const { return _hrs.at(index); } 1366 1367 // Divide the heap region sequence into "chunks" of some size (the number 1368 // of regions divided by the number of parallel threads times some 1369 // overpartition factor, currently 4). Assumes that this will be called 1370 // in parallel by ParallelGCThreads worker threads with discinct worker 1371 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel 1372 // calls will use the same "claim_value", and that that claim value is 1373 // different from the claim_value of any heap region before the start of 1374 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by 1375 // attempting to claim the first region in each chunk, and, if 1376 // successful, applying the closure to each region in the chunk (and 1377 // setting the claim value of the second and subsequent regions of the 1378 // chunk.) For now requires that "doHeapRegion" always returns "false", 1379 // i.e., that a closure never attempt to abort a traversal. 1380 void heap_region_par_iterate_chunked(HeapRegionClosure* blk, 1381 uint worker, 1382 uint no_of_par_workers, 1383 jint claim_value); 1384 1385 // It resets all the region claim values to the default. 1386 void reset_heap_region_claim_values(); 1387 1388 // Resets the claim values of regions in the current 1389 // collection set to the default. 1390 void reset_cset_heap_region_claim_values(); 1391 1392 #ifdef ASSERT 1393 bool check_heap_region_claim_values(jint claim_value); 1394 1395 // Same as the routine above but only checks regions in the 1396 // current collection set. 1397 bool check_cset_heap_region_claim_values(jint claim_value); 1398 #endif // ASSERT 1399 1400 // Clear the cached cset start regions and (more importantly) 1401 // the time stamps. Called when we reset the GC time stamp. 1402 void clear_cset_start_regions(); 1403 1404 // Given the id of a worker, obtain or calculate a suitable 1405 // starting region for iterating over the current collection set. 1406 HeapRegion* start_cset_region_for_worker(int worker_i); 1407 1408 // This is a convenience method that is used by the 1409 // HeapRegionIterator classes to calculate the starting region for 1410 // each worker so that they do not all start from the same region. 1411 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers); 1412 1413 // Iterate over the regions (if any) in the current collection set. 1414 void collection_set_iterate(HeapRegionClosure* blk); 1415 1416 // As above but starting from region r 1417 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1418 1419 // Returns the first (lowest address) compactible space in the heap. 1420 virtual CompactibleSpace* first_compactible_space(); 1421 1422 // A CollectedHeap will contain some number of spaces. This finds the 1423 // space containing a given address, or else returns NULL. 1424 virtual Space* space_containing(const void* addr) const; 1425 1426 // A G1CollectedHeap will contain some number of heap regions. This 1427 // finds the region containing a given address, or else returns NULL. 1428 template <class T> 1429 inline HeapRegion* heap_region_containing(const T addr) const; 1430 1431 // Like the above, but requires "addr" to be in the heap (to avoid a 1432 // null-check), and unlike the above, may return an continuing humongous 1433 // region. 1434 template <class T> 1435 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1436 1437 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1438 // each address in the (reserved) heap is a member of exactly 1439 // one block. The defining characteristic of a block is that it is 1440 // possible to find its size, and thus to progress forward to the next 1441 // block. (Blocks may be of different sizes.) Thus, blocks may 1442 // represent Java objects, or they might be free blocks in a 1443 // free-list-based heap (or subheap), as long as the two kinds are 1444 // distinguishable and the size of each is determinable. 1445 1446 // Returns the address of the start of the "block" that contains the 1447 // address "addr". We say "blocks" instead of "object" since some heaps 1448 // may not pack objects densely; a chunk may either be an object or a 1449 // non-object. 1450 virtual HeapWord* block_start(const void* addr) const; 1451 1452 // Requires "addr" to be the start of a chunk, and returns its size. 1453 // "addr + size" is required to be the start of a new chunk, or the end 1454 // of the active area of the heap. 1455 virtual size_t block_size(const HeapWord* addr) const; 1456 1457 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1458 // the block is an object. 1459 virtual bool block_is_obj(const HeapWord* addr) const; 1460 1461 // Does this heap support heap inspection? (+PrintClassHistogram) 1462 virtual bool supports_heap_inspection() const { return true; } 1463 1464 // Section on thread-local allocation buffers (TLABs) 1465 // See CollectedHeap for semantics. 1466 1467 virtual bool supports_tlab_allocation() const; 1468 virtual size_t tlab_capacity(Thread* thr) const; 1469 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const; 1470 1471 // Can a compiler initialize a new object without store barriers? 1472 // This permission only extends from the creation of a new object 1473 // via a TLAB up to the first subsequent safepoint. If such permission 1474 // is granted for this heap type, the compiler promises to call 1475 // defer_store_barrier() below on any slow path allocation of 1476 // a new object for which such initializing store barriers will 1477 // have been elided. G1, like CMS, allows this, but should be 1478 // ready to provide a compensating write barrier as necessary 1479 // if that storage came out of a non-young region. The efficiency 1480 // of this implementation depends crucially on being able to 1481 // answer very efficiently in constant time whether a piece of 1482 // storage in the heap comes from a young region or not. 1483 // See ReduceInitialCardMarks. 1484 virtual bool can_elide_tlab_store_barriers() const { 1485 return true; 1486 } 1487 1488 virtual bool card_mark_must_follow_store() const { 1489 return true; 1490 } 1491 1492 bool is_in_young(const oop obj) { 1493 HeapRegion* hr = heap_region_containing(obj); 1494 return hr != NULL && hr->is_young(); 1495 } 1496 1497 #ifdef ASSERT 1498 virtual bool is_in_partial_collection(const void* p); 1499 #endif 1500 1501 virtual bool is_scavengable(const void* addr); 1502 1503 // We don't need barriers for initializing stores to objects 1504 // in the young gen: for the SATB pre-barrier, there is no 1505 // pre-value that needs to be remembered; for the remembered-set 1506 // update logging post-barrier, we don't maintain remembered set 1507 // information for young gen objects. 1508 virtual bool can_elide_initializing_store_barrier(oop new_obj) { 1509 return is_in_young(new_obj); 1510 } 1511 1512 // Returns "true" iff the given word_size is "very large". 1513 static bool isHumongous(size_t word_size) { 1514 // Note this has to be strictly greater-than as the TLABs 1515 // are capped at the humongous thresold and we want to 1516 // ensure that we don't try to allocate a TLAB as 1517 // humongous and that we don't allocate a humongous 1518 // object in a TLAB. 1519 return word_size > _humongous_object_threshold_in_words; 1520 } 1521 1522 // Update mod union table with the set of dirty cards. 1523 void updateModUnion(); 1524 1525 // Set the mod union bits corresponding to the given memRegion. Note 1526 // that this is always a safe operation, since it doesn't clear any 1527 // bits. 1528 void markModUnionRange(MemRegion mr); 1529 1530 // Records the fact that a marking phase is no longer in progress. 1531 void set_marking_complete() { 1532 _mark_in_progress = false; 1533 } 1534 void set_marking_started() { 1535 _mark_in_progress = true; 1536 } 1537 bool mark_in_progress() { 1538 return _mark_in_progress; 1539 } 1540 1541 // Print the maximum heap capacity. 1542 virtual size_t max_capacity() const; 1543 1544 virtual jlong millis_since_last_gc(); 1545 1546 // Perform any cleanup actions necessary before allowing a verification. 1547 virtual void prepare_for_verify(); 1548 1549 // Perform verification. 1550 1551 // vo == UsePrevMarking -> use "prev" marking information, 1552 // vo == UseNextMarking -> use "next" marking information 1553 // vo == UseMarkWord -> use the mark word in the object header 1554 // 1555 // NOTE: Only the "prev" marking information is guaranteed to be 1556 // consistent most of the time, so most calls to this should use 1557 // vo == UsePrevMarking. 1558 // Currently, there is only one case where this is called with 1559 // vo == UseNextMarking, which is to verify the "next" marking 1560 // information at the end of remark. 1561 // Currently there is only one place where this is called with 1562 // vo == UseMarkWord, which is to verify the marking during a 1563 // full GC. 1564 void verify(bool silent, VerifyOption vo); 1565 1566 // Override; it uses the "prev" marking information 1567 virtual void verify(bool silent); 1568 virtual void print_on(outputStream* st) const; 1569 virtual void print_extended_on(outputStream* st) const; 1570 1571 virtual void print_gc_threads_on(outputStream* st) const; 1572 virtual void gc_threads_do(ThreadClosure* tc) const; 1573 1574 // Override 1575 void print_tracing_info() const; 1576 1577 // The following two methods are helpful for debugging RSet issues. 1578 void print_cset_rsets() PRODUCT_RETURN; 1579 void print_all_rsets() PRODUCT_RETURN; 1580 1581 // Convenience function to be used in situations where the heap type can be 1582 // asserted to be this type. 1583 static G1CollectedHeap* heap(); 1584 1585 void set_region_short_lived_locked(HeapRegion* hr); 1586 // add appropriate methods for any other surv rate groups 1587 1588 YoungList* young_list() { return _young_list; } 1589 1590 // debugging 1591 bool check_young_list_well_formed() { 1592 return _young_list->check_list_well_formed(); 1593 } 1594 1595 bool check_young_list_empty(bool check_heap, 1596 bool check_sample = true); 1597 1598 // *** Stuff related to concurrent marking. It's not clear to me that so 1599 // many of these need to be public. 1600 1601 // The functions below are helper functions that a subclass of 1602 // "CollectedHeap" can use in the implementation of its virtual 1603 // functions. 1604 // This performs a concurrent marking of the live objects in a 1605 // bitmap off to the side. 1606 void doConcurrentMark(); 1607 1608 bool isMarkedPrev(oop obj) const; 1609 bool isMarkedNext(oop obj) const; 1610 1611 // Determine if an object is dead, given the object and also 1612 // the region to which the object belongs. An object is dead 1613 // iff a) it was not allocated since the last mark and b) it 1614 // is not marked. 1615 1616 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1617 return 1618 !hr->obj_allocated_since_prev_marking(obj) && 1619 !isMarkedPrev(obj); 1620 } 1621 1622 // This function returns true when an object has been 1623 // around since the previous marking and hasn't yet 1624 // been marked during this marking. 1625 1626 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1627 return 1628 !hr->obj_allocated_since_next_marking(obj) && 1629 !isMarkedNext(obj); 1630 } 1631 1632 // Determine if an object is dead, given only the object itself. 1633 // This will find the region to which the object belongs and 1634 // then call the region version of the same function. 1635 1636 // Added if it is NULL it isn't dead. 1637 1638 bool is_obj_dead(const oop obj) const { 1639 const HeapRegion* hr = heap_region_containing(obj); 1640 if (hr == NULL) { 1641 if (obj == NULL) return false; 1642 else return true; 1643 } 1644 else return is_obj_dead(obj, hr); 1645 } 1646 1647 bool is_obj_ill(const oop obj) const { 1648 const HeapRegion* hr = heap_region_containing(obj); 1649 if (hr == NULL) { 1650 if (obj == NULL) return false; 1651 else return true; 1652 } 1653 else return is_obj_ill(obj, hr); 1654 } 1655 1656 // The methods below are here for convenience and dispatch the 1657 // appropriate method depending on value of the given VerifyOption 1658 // parameter. The options for that parameter are: 1659 // 1660 // vo == UsePrevMarking -> use "prev" marking information, 1661 // vo == UseNextMarking -> use "next" marking information, 1662 // vo == UseMarkWord -> use mark word from object header 1663 1664 bool is_obj_dead_cond(const oop obj, 1665 const HeapRegion* hr, 1666 const VerifyOption vo) const { 1667 switch (vo) { 1668 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 1669 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 1670 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 1671 default: ShouldNotReachHere(); 1672 } 1673 return false; // keep some compilers happy 1674 } 1675 1676 bool is_obj_dead_cond(const oop obj, 1677 const VerifyOption vo) const { 1678 switch (vo) { 1679 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 1680 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 1681 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 1682 default: ShouldNotReachHere(); 1683 } 1684 return false; // keep some compilers happy 1685 } 1686 1687 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1688 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1689 bool is_marked(oop obj, VerifyOption vo); 1690 const char* top_at_mark_start_str(VerifyOption vo); 1691 1692 // The following is just to alert the verification code 1693 // that a full collection has occurred and that the 1694 // remembered sets are no longer up to date. 1695 bool _full_collection; 1696 void set_full_collection() { _full_collection = true;} 1697 void clear_full_collection() {_full_collection = false;} 1698 bool full_collection() {return _full_collection;} 1699 1700 ConcurrentMark* concurrent_mark() const { return _cm; } 1701 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1702 1703 // The dirty cards region list is used to record a subset of regions 1704 // whose cards need clearing. The list if populated during the 1705 // remembered set scanning and drained during the card table 1706 // cleanup. Although the methods are reentrant, population/draining 1707 // phases must not overlap. For synchronization purposes the last 1708 // element on the list points to itself. 1709 HeapRegion* _dirty_cards_region_list; 1710 void push_dirty_cards_region(HeapRegion* hr); 1711 HeapRegion* pop_dirty_cards_region(); 1712 1713 public: 1714 void stop_conc_gc_threads(); 1715 1716 size_t pending_card_num(); 1717 size_t cards_scanned(); 1718 1719 protected: 1720 size_t _max_heap_capacity; 1721 }; 1722 1723 class G1ParGCAllocBuffer: public ParGCAllocBuffer { 1724 private: 1725 bool _retired; 1726 1727 public: 1728 G1ParGCAllocBuffer(size_t gclab_word_size); 1729 1730 void set_buf(HeapWord* buf) { 1731 ParGCAllocBuffer::set_buf(buf); 1732 _retired = false; 1733 } 1734 1735 void retire(bool end_of_gc, bool retain) { 1736 if (_retired) 1737 return; 1738 ParGCAllocBuffer::retire(end_of_gc, retain); 1739 _retired = true; 1740 } 1741 }; 1742 1743 class G1ParScanThreadState : public StackObj { 1744 private: 1745 enum GCAllocPriority { 1746 GCAllocPriority1, 1747 GCAllocPriority2, 1748 GCAllocPriorityCount 1749 }; 1750 1751 int buf_idx(int purpose, int priority) { 1752 return purpose*GCAllocPriorityCount + priority; 1753 } 1754 1755 protected: 1756 G1CollectedHeap* _g1h; 1757 RefToScanQueue* _refs; 1758 DirtyCardQueue _dcq; 1759 CardTableModRefBS* _ct_bs; 1760 G1RemSet* _g1_rem; 1761 1762 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount*GCAllocPriorityCount]; 1763 ageTable _age_table; 1764 1765 size_t _alloc_buffer_waste; 1766 size_t _undo_waste; 1767 1768 OopsInHeapRegionClosure* _evac_failure_cl; 1769 G1ParScanHeapEvacClosure* _evac_cl; 1770 G1ParScanPartialArrayClosure* _partial_scan_cl; 1771 1772 int _hash_seed; 1773 uint _queue_num; 1774 1775 size_t _term_attempts; 1776 1777 double _start; 1778 double _start_strong_roots; 1779 double _strong_roots_time; 1780 double _start_term; 1781 double _term_time; 1782 1783 // Map from young-age-index (0 == not young, 1 is youngest) to 1784 // surviving words. base is what we get back from the malloc call 1785 size_t* _surviving_young_words_base; 1786 // this points into the array, as we use the first few entries for padding 1787 size_t* _surviving_young_words; 1788 1789 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t)) 1790 1791 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; } 1792 1793 void add_to_undo_waste(size_t waste) { _undo_waste += waste; } 1794 1795 DirtyCardQueue& dirty_card_queue() { return _dcq; } 1796 CardTableModRefBS* ctbs() { return _ct_bs; } 1797 1798 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) { 1799 if (!from->is_survivor()) { 1800 _g1_rem->par_write_ref(from, p, tid); 1801 } 1802 } 1803 1804 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) { 1805 // If the new value of the field points to the same region or 1806 // is the to-space, we don't need to include it in the Rset updates. 1807 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) { 1808 size_t card_index = ctbs()->index_for(p); 1809 // If the card hasn't been added to the buffer, do it. 1810 if (ctbs()->mark_card_deferred(card_index)) { 1811 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index)); 1812 } 1813 } 1814 } 1815 1816 public: 1817 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num); 1818 1819 ~G1ParScanThreadState() { 1820 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC); 1821 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) 1822 for (int pr = 0; pr < GCAllocPriorityCount; ++pr) { 1823 delete alloc_buffer(GCAllocPurpose(ap), GCAllocPriority(pr)); 1824 } 1825 } 1826 1827 RefToScanQueue* refs() { return _refs; } 1828 ageTable* age_table() { return &_age_table; } 1829 1830 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose, GCAllocPriority priority) { 1831 return _alloc_buffers[buf_idx(purpose, priority)]; 1832 } 1833 1834 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; } 1835 size_t undo_waste() const { return _undo_waste; } 1836 1837 #ifdef ASSERT 1838 bool verify_ref(narrowOop* ref) const; 1839 bool verify_ref(oop* ref) const; 1840 bool verify_task(StarTask ref) const; 1841 #endif // ASSERT 1842 1843 template <class T> void push_on_queue(T* ref) { 1844 assert(verify_ref(ref), "sanity"); 1845 refs()->push(ref); 1846 } 1847 1848 template <class T> void update_rs(HeapRegion* from, T* p, int tid) { 1849 if (G1DeferredRSUpdate) { 1850 deferred_rs_update(from, p, tid); 1851 } else { 1852 immediate_rs_update(from, p, tid); 1853 } 1854 } 1855 1856 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) { 1857 HeapWord* obj = NULL; 1858 size_t gclab_word_size = _g1h->desired_plab_sz(purpose); 1859 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) { 1860 G1ParGCAllocBuffer* alloc_buf1 = alloc_buffer(purpose, GCAllocPriority1); 1861 G1ParGCAllocBuffer* alloc_buf2 = alloc_buffer(purpose, GCAllocPriority2); 1862 1863 add_to_alloc_buffer_waste(alloc_buf1->words_remaining()); 1864 alloc_buf1->retire(false /* end_of_gc */, false /* retain */); 1865 1866 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size); 1867 if (buf == NULL) return NULL; // Let caller handle allocation failure. 1868 // Otherwise. 1869 alloc_buf1->set_word_size(gclab_word_size); 1870 alloc_buf1->set_buf(buf); 1871 1872 obj = alloc_buf1->allocate(word_sz); 1873 assert(obj != NULL, "buffer was definitely big enough..."); 1874 1875 // Swap buffers in order to preserve the priority order 1876 _alloc_buffers[buf_idx(purpose, GCAllocPriority1)] = alloc_buf2; 1877 _alloc_buffers[buf_idx(purpose, GCAllocPriority2)] = alloc_buf1; 1878 } else { 1879 obj = _g1h->par_allocate_during_gc(purpose, word_sz); 1880 } 1881 return obj; 1882 } 1883 1884 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) { 1885 HeapWord* obj; 1886 for (int pr = 0; pr < GCAllocPriorityCount; ++pr) { 1887 obj = alloc_buffer(purpose, (GCAllocPriority)pr)->allocate(word_sz); 1888 if (obj != NULL) return obj; 1889 } 1890 // Otherwise. 1891 return allocate_slow(purpose, word_sz); 1892 } 1893 1894 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) { 1895 for (int pr = 0; pr < GCAllocPriorityCount; ++pr) { 1896 if (alloc_buffer(purpose, (GCAllocPriority)pr)->contains(obj)) { 1897 assert(alloc_buffer(purpose, pr)->contains(obj + word_sz - 1), 1898 "should contain whole object"); 1899 alloc_buffer(purpose, (GCAllocPriority)pr)->undo_allocation(obj, word_sz); 1900 return; 1901 } 1902 } 1903 1904 CollectedHeap::fill_with_object(obj, word_sz); 1905 add_to_undo_waste(word_sz); 1906 } 1907 1908 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) { 1909 _evac_failure_cl = evac_failure_cl; 1910 } 1911 OopsInHeapRegionClosure* evac_failure_closure() { 1912 return _evac_failure_cl; 1913 } 1914 1915 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) { 1916 _evac_cl = evac_cl; 1917 } 1918 1919 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) { 1920 _partial_scan_cl = partial_scan_cl; 1921 } 1922 1923 int* hash_seed() { return &_hash_seed; } 1924 uint queue_num() { return _queue_num; } 1925 1926 size_t term_attempts() const { return _term_attempts; } 1927 void note_term_attempt() { _term_attempts++; } 1928 1929 void start_strong_roots() { 1930 _start_strong_roots = os::elapsedTime(); 1931 } 1932 void end_strong_roots() { 1933 _strong_roots_time += (os::elapsedTime() - _start_strong_roots); 1934 } 1935 double strong_roots_time() const { return _strong_roots_time; } 1936 1937 void start_term_time() { 1938 note_term_attempt(); 1939 _start_term = os::elapsedTime(); 1940 } 1941 void end_term_time() { 1942 _term_time += (os::elapsedTime() - _start_term); 1943 } 1944 double term_time() const { return _term_time; } 1945 1946 double elapsed_time() const { 1947 return os::elapsedTime() - _start; 1948 } 1949 1950 static void 1951 print_termination_stats_hdr(outputStream* const st = gclog_or_tty); 1952 void 1953 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const; 1954 1955 size_t* surviving_young_words() { 1956 // We add on to hide entry 0 which accumulates surviving words for 1957 // age -1 regions (i.e. non-young ones) 1958 return _surviving_young_words; 1959 } 1960 1961 void retire_alloc_buffers() { 1962 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) 1963 for (int pr = 0; pr < GCAllocPriorityCount; ++pr) { 1964 G1ParGCAllocBuffer* buffer = alloc_buffer((GCAllocPurpose)ap, (GCAllocPriority)pr); 1965 size_t waste = buffer->words_remaining(); 1966 add_to_alloc_buffer_waste(waste); 1967 buffer->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap), 1968 true /* end_of_gc */, 1969 false /* retain */); 1970 } 1971 } 1972 1973 template <class T> void deal_with_reference(T* ref_to_scan) { 1974 if (has_partial_array_mask(ref_to_scan)) { 1975 _partial_scan_cl->do_oop_nv(ref_to_scan); 1976 } else { 1977 // Note: we can use "raw" versions of "region_containing" because 1978 // "obj_to_scan" is definitely in the heap, and is not in a 1979 // humongous region. 1980 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan); 1981 _evac_cl->set_region(r); 1982 _evac_cl->do_oop_nv(ref_to_scan); 1983 } 1984 } 1985 1986 void deal_with_reference(StarTask ref) { 1987 assert(verify_task(ref), "sanity"); 1988 if (ref.is_narrow()) { 1989 deal_with_reference((narrowOop*)ref); 1990 } else { 1991 deal_with_reference((oop*)ref); 1992 } 1993 } 1994 1995 void trim_queue(); 1996 }; 1997 1998 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP