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 #include "utilities/stack.hpp" 41 42 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 43 // It uses the "Garbage First" heap organization and algorithm, which 44 // may combine concurrent marking with parallel, incremental compaction of 45 // heap subsets that will yield large amounts of garbage. 46 47 class HeapRegion; 48 class HRRSCleanupTask; 49 class GenerationSpec; 50 class OopsInHeapRegionClosure; 51 class G1KlassScanClosure; 52 class G1ScanHeapEvacClosure; 53 class ObjectClosure; 54 class SpaceClosure; 55 class CompactibleSpaceClosure; 56 class Space; 57 class G1CollectorPolicy; 58 class GenRemSet; 59 class G1RemSet; 60 class HeapRegionRemSetIterator; 61 class ConcurrentMark; 62 class ConcurrentMarkThread; 63 class ConcurrentG1Refine; 64 class GenerationCounters; 65 66 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 67 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 68 69 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 70 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 71 72 enum GCAllocPurpose { 73 GCAllocForTenured, 74 GCAllocForSurvived, 75 GCAllocPurposeCount 76 }; 77 78 class YoungList : public CHeapObj<mtGC> { 79 private: 80 G1CollectedHeap* _g1h; 81 82 HeapRegion* _head; 83 84 HeapRegion* _survivor_head; 85 HeapRegion* _survivor_tail; 86 87 HeapRegion* _curr; 88 89 uint _length; 90 uint _survivor_length; 91 92 size_t _last_sampled_rs_lengths; 93 size_t _sampled_rs_lengths; 94 95 void empty_list(HeapRegion* list); 96 97 public: 98 YoungList(G1CollectedHeap* g1h); 99 100 void push_region(HeapRegion* hr); 101 void add_survivor_region(HeapRegion* hr); 102 103 void empty_list(); 104 bool is_empty() { return _length == 0; } 105 uint length() { return _length; } 106 uint survivor_length() { return _survivor_length; } 107 108 // Currently we do not keep track of the used byte sum for the 109 // young list and the survivors and it'd be quite a lot of work to 110 // do so. When we'll eventually replace the young list with 111 // instances of HeapRegionLinkedList we'll get that for free. So, 112 // we'll report the more accurate information then. 113 size_t eden_used_bytes() { 114 assert(length() >= survivor_length(), "invariant"); 115 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes; 116 } 117 size_t survivor_used_bytes() { 118 return (size_t) survivor_length() * HeapRegion::GrainBytes; 119 } 120 121 void rs_length_sampling_init(); 122 bool rs_length_sampling_more(); 123 void rs_length_sampling_next(); 124 125 void reset_sampled_info() { 126 _last_sampled_rs_lengths = 0; 127 } 128 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; } 129 130 // for development purposes 131 void reset_auxilary_lists(); 132 void clear() { _head = NULL; _length = 0; } 133 134 void clear_survivors() { 135 _survivor_head = NULL; 136 _survivor_tail = NULL; 137 _survivor_length = 0; 138 } 139 140 HeapRegion* first_region() { return _head; } 141 HeapRegion* first_survivor_region() { return _survivor_head; } 142 HeapRegion* last_survivor_region() { return _survivor_tail; } 143 144 // debugging 145 bool check_list_well_formed(); 146 bool check_list_empty(bool check_sample = true); 147 void print(); 148 }; 149 150 class MutatorAllocRegion : public G1AllocRegion { 151 protected: 152 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 153 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 154 public: 155 MutatorAllocRegion() 156 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { } 157 }; 158 159 // The G1 STW is alive closure. 160 // An instance is embedded into the G1CH and used as the 161 // (optional) _is_alive_non_header closure in the STW 162 // reference processor. It is also extensively used during 163 // refence processing during STW evacuation pauses. 164 class G1STWIsAliveClosure: public BoolObjectClosure { 165 G1CollectedHeap* _g1; 166 public: 167 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 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 int* gclocker_retry_count_ret); 563 564 // Second-level mutator allocation attempt: take the Heap_lock and 565 // retry the allocation attempt, potentially scheduling a GC 566 // pause. This should only be used for non-humongous allocations. 567 HeapWord* attempt_allocation_slow(size_t word_size, 568 unsigned int* gc_count_before_ret, 569 int* gclocker_retry_count_ret); 570 571 // Takes the Heap_lock and attempts a humongous allocation. It can 572 // potentially schedule a GC pause. 573 HeapWord* attempt_allocation_humongous(size_t word_size, 574 unsigned int* gc_count_before_ret, 575 int* gclocker_retry_count_ret); 576 577 // Allocation attempt that should be called during safepoints (e.g., 578 // at the end of a successful GC). expect_null_mutator_alloc_region 579 // specifies whether the mutator alloc region is expected to be NULL 580 // or not. 581 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 582 bool expect_null_mutator_alloc_region); 583 584 // It dirties the cards that cover the block so that so that the post 585 // write barrier never queues anything when updating objects on this 586 // block. It is assumed (and in fact we assert) that the block 587 // belongs to a young region. 588 inline void dirty_young_block(HeapWord* start, size_t word_size); 589 590 // Allocate blocks during garbage collection. Will ensure an 591 // allocation region, either by picking one or expanding the 592 // heap, and then allocate a block of the given size. The block 593 // may not be a humongous - it must fit into a single heap region. 594 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size); 595 596 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose, 597 HeapRegion* alloc_region, 598 bool par, 599 size_t word_size); 600 601 // Ensure that no further allocations can happen in "r", bearing in mind 602 // that parallel threads might be attempting allocations. 603 void par_allocate_remaining_space(HeapRegion* r); 604 605 // Allocation attempt during GC for a survivor object / PLAB. 606 inline HeapWord* survivor_attempt_allocation(size_t word_size); 607 608 // Allocation attempt during GC for an old object / PLAB. 609 inline HeapWord* old_attempt_allocation(size_t word_size); 610 611 // These methods are the "callbacks" from the G1AllocRegion class. 612 613 // For mutator alloc regions. 614 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 615 void retire_mutator_alloc_region(HeapRegion* alloc_region, 616 size_t allocated_bytes); 617 618 // For GC alloc regions. 619 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 620 GCAllocPurpose ap); 621 void retire_gc_alloc_region(HeapRegion* alloc_region, 622 size_t allocated_bytes, GCAllocPurpose ap); 623 624 // - if explicit_gc is true, the GC is for a System.gc() or a heap 625 // inspection request and should collect the entire heap 626 // - if clear_all_soft_refs is true, all soft references should be 627 // cleared during the GC 628 // - if explicit_gc is false, word_size describes the allocation that 629 // the GC should attempt (at least) to satisfy 630 // - it returns false if it is unable to do the collection due to the 631 // GC locker being active, true otherwise 632 bool do_collection(bool explicit_gc, 633 bool clear_all_soft_refs, 634 size_t word_size); 635 636 // Callback from VM_G1CollectFull operation. 637 // Perform a full collection. 638 virtual void do_full_collection(bool clear_all_soft_refs); 639 640 // Resize the heap if necessary after a full collection. If this is 641 // after a collect-for allocation, "word_size" is the allocation size, 642 // and will be considered part of the used portion of the heap. 643 void resize_if_necessary_after_full_collection(size_t word_size); 644 645 // Callback from VM_G1CollectForAllocation operation. 646 // This function does everything necessary/possible to satisfy a 647 // failed allocation request (including collection, expansion, etc.) 648 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded); 649 650 // Attempting to expand the heap sufficiently 651 // to support an allocation of the given "word_size". If 652 // successful, perform the allocation and return the address of the 653 // allocated block, or else "NULL". 654 HeapWord* expand_and_allocate(size_t word_size); 655 656 // Process any reference objects discovered during 657 // an incremental evacuation pause. 658 void process_discovered_references(uint no_of_gc_workers); 659 660 // Enqueue any remaining discovered references 661 // after processing. 662 void enqueue_discovered_references(uint no_of_gc_workers); 663 664 public: 665 666 G1MonitoringSupport* g1mm() { 667 assert(_g1mm != NULL, "should have been initialized"); 668 return _g1mm; 669 } 670 671 // Expand the garbage-first heap by at least the given size (in bytes!). 672 // Returns true if the heap was expanded by the requested amount; 673 // false otherwise. 674 // (Rounds up to a HeapRegion boundary.) 675 bool expand(size_t expand_bytes); 676 677 // Do anything common to GC's. 678 virtual void gc_prologue(bool full); 679 virtual void gc_epilogue(bool full); 680 681 // We register a region with the fast "in collection set" test. We 682 // simply set to true the array slot corresponding to this region. 683 void register_region_with_in_cset_fast_test(HeapRegion* r) { 684 assert(_in_cset_fast_test_base != NULL, "sanity"); 685 assert(r->in_collection_set(), "invariant"); 686 uint index = r->hrs_index(); 687 assert(index < _in_cset_fast_test_length, "invariant"); 688 assert(!_in_cset_fast_test_base[index], "invariant"); 689 _in_cset_fast_test_base[index] = true; 690 } 691 692 // This is a fast test on whether a reference points into the 693 // collection set or not. It does not assume that the reference 694 // points into the heap; if it doesn't, it will return false. 695 bool in_cset_fast_test(oop obj) { 696 assert(_in_cset_fast_test != NULL, "sanity"); 697 if (_g1_committed.contains((HeapWord*) obj)) { 698 // no need to subtract the bottom of the heap from obj, 699 // _in_cset_fast_test is biased 700 uintx index = (uintx) obj >> HeapRegion::LogOfHRGrainBytes; 701 bool ret = _in_cset_fast_test[index]; 702 // let's make sure the result is consistent with what the slower 703 // test returns 704 assert( ret || !obj_in_cs(obj), "sanity"); 705 assert(!ret || obj_in_cs(obj), "sanity"); 706 return ret; 707 } else { 708 return false; 709 } 710 } 711 712 void clear_cset_fast_test() { 713 assert(_in_cset_fast_test_base != NULL, "sanity"); 714 memset(_in_cset_fast_test_base, false, 715 (size_t) _in_cset_fast_test_length * sizeof(bool)); 716 } 717 718 // This is called at the start of either a concurrent cycle or a Full 719 // GC to update the number of old marking cycles started. 720 void increment_old_marking_cycles_started(); 721 722 // This is called at the end of either a concurrent cycle or a Full 723 // GC to update the number of old marking cycles completed. Those two 724 // can happen in a nested fashion, i.e., we start a concurrent 725 // cycle, a Full GC happens half-way through it which ends first, 726 // and then the cycle notices that a Full GC happened and ends 727 // too. The concurrent parameter is a boolean to help us do a bit 728 // tighter consistency checking in the method. If concurrent is 729 // false, the caller is the inner caller in the nesting (i.e., the 730 // Full GC). If concurrent is true, the caller is the outer caller 731 // in this nesting (i.e., the concurrent cycle). Further nesting is 732 // not currently supported. The end of this call also notifies 733 // the FullGCCount_lock in case a Java thread is waiting for a full 734 // GC to happen (e.g., it called System.gc() with 735 // +ExplicitGCInvokesConcurrent). 736 void increment_old_marking_cycles_completed(bool concurrent); 737 738 unsigned int old_marking_cycles_completed() { 739 return _old_marking_cycles_completed; 740 } 741 742 G1HRPrinter* hr_printer() { return &_hr_printer; } 743 744 protected: 745 746 // Shrink the garbage-first heap by at most the given size (in bytes!). 747 // (Rounds down to a HeapRegion boundary.) 748 virtual void shrink(size_t expand_bytes); 749 void shrink_helper(size_t expand_bytes); 750 751 #if TASKQUEUE_STATS 752 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 753 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 754 void reset_taskqueue_stats(); 755 #endif // TASKQUEUE_STATS 756 757 // Schedule the VM operation that will do an evacuation pause to 758 // satisfy an allocation request of word_size. *succeeded will 759 // return whether the VM operation was successful (it did do an 760 // evacuation pause) or not (another thread beat us to it or the GC 761 // locker was active). Given that we should not be holding the 762 // Heap_lock when we enter this method, we will pass the 763 // gc_count_before (i.e., total_collections()) as a parameter since 764 // it has to be read while holding the Heap_lock. Currently, both 765 // methods that call do_collection_pause() release the Heap_lock 766 // before the call, so it's easy to read gc_count_before just before. 767 HeapWord* do_collection_pause(size_t word_size, 768 unsigned int gc_count_before, 769 bool* succeeded); 770 771 // The guts of the incremental collection pause, executed by the vm 772 // thread. It returns false if it is unable to do the collection due 773 // to the GC locker being active, true otherwise 774 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 775 776 // Actually do the work of evacuating the collection set. 777 void evacuate_collection_set(); 778 779 // The g1 remembered set of the heap. 780 G1RemSet* _g1_rem_set; 781 // And it's mod ref barrier set, used to track updates for the above. 782 ModRefBarrierSet* _mr_bs; 783 784 // A set of cards that cover the objects for which the Rsets should be updated 785 // concurrently after the collection. 786 DirtyCardQueueSet _dirty_card_queue_set; 787 788 // The closure used to refine a single card. 789 RefineCardTableEntryClosure* _refine_cte_cl; 790 791 // A function to check the consistency of dirty card logs. 792 void check_ct_logs_at_safepoint(); 793 794 // A DirtyCardQueueSet that is used to hold cards that contain 795 // references into the current collection set. This is used to 796 // update the remembered sets of the regions in the collection 797 // set in the event of an evacuation failure. 798 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 799 800 // After a collection pause, make the regions in the CS into free 801 // regions. 802 void free_collection_set(HeapRegion* cs_head); 803 804 // Abandon the current collection set without recording policy 805 // statistics or updating free lists. 806 void abandon_collection_set(HeapRegion* cs_head); 807 808 // Applies "scan_non_heap_roots" to roots outside the heap, 809 // "scan_rs" to roots inside the heap (having done "set_region" to 810 // indicate the region in which the root resides), 811 // and does "scan_metadata" If "scan_rs" is 812 // NULL, then this step is skipped. The "worker_i" 813 // param is for use with parallel roots processing, and should be 814 // the "i" of the calling parallel worker thread's work(i) function. 815 // In the sequential case this param will be ignored. 816 void g1_process_strong_roots(bool is_scavenging, 817 ScanningOption so, 818 OopClosure* scan_non_heap_roots, 819 OopsInHeapRegionClosure* scan_rs, 820 G1KlassScanClosure* scan_klasses, 821 int worker_i); 822 823 // Apply "blk" to all the weak roots of the system. These include 824 // JNI weak roots, the code cache, system dictionary, symbol table, 825 // string table, and referents of reachable weak refs. 826 void g1_process_weak_roots(OopClosure* root_closure); 827 828 // Frees a non-humongous region by initializing its contents and 829 // adding it to the free list that's passed as a parameter (this is 830 // usually a local list which will be appended to the master free 831 // list later). The used bytes of freed regions are accumulated in 832 // pre_used. If par is true, the region's RSet will not be freed 833 // up. The assumption is that this will be done later. 834 void free_region(HeapRegion* hr, 835 size_t* pre_used, 836 FreeRegionList* free_list, 837 bool par); 838 839 // Frees a humongous region by collapsing it into individual regions 840 // and calling free_region() for each of them. The freed regions 841 // will be added to the free list that's passed as a parameter (this 842 // is usually a local list which will be appended to the master free 843 // list later). The used bytes of freed regions are accumulated in 844 // pre_used. If par is true, the region's RSet will not be freed 845 // up. The assumption is that this will be done later. 846 void free_humongous_region(HeapRegion* hr, 847 size_t* pre_used, 848 FreeRegionList* free_list, 849 HumongousRegionSet* humongous_proxy_set, 850 bool par); 851 852 // Notifies all the necessary spaces that the committed space has 853 // been updated (either expanded or shrunk). It should be called 854 // after _g1_storage is updated. 855 void update_committed_space(HeapWord* old_end, HeapWord* new_end); 856 857 // The concurrent marker (and the thread it runs in.) 858 ConcurrentMark* _cm; 859 ConcurrentMarkThread* _cmThread; 860 bool _mark_in_progress; 861 862 // The concurrent refiner. 863 ConcurrentG1Refine* _cg1r; 864 865 // The parallel task queues 866 RefToScanQueueSet *_task_queues; 867 868 // True iff a evacuation has failed in the current collection. 869 bool _evacuation_failed; 870 871 // Set the attribute indicating whether evacuation has failed in the 872 // current collection. 873 void set_evacuation_failed(bool b) { _evacuation_failed = b; } 874 875 // Failed evacuations cause some logical from-space objects to have 876 // forwarding pointers to themselves. Reset them. 877 void remove_self_forwarding_pointers(); 878 879 // Together, these store an object with a preserved mark, and its mark value. 880 Stack<oop, mtGC> _objs_with_preserved_marks; 881 Stack<markOop, mtGC> _preserved_marks_of_objs; 882 883 // Preserve the mark of "obj", if necessary, in preparation for its mark 884 // word being overwritten with a self-forwarding-pointer. 885 void preserve_mark_if_necessary(oop obj, markOop m); 886 887 // The stack of evac-failure objects left to be scanned. 888 GrowableArray<oop>* _evac_failure_scan_stack; 889 // The closure to apply to evac-failure objects. 890 891 OopsInHeapRegionClosure* _evac_failure_closure; 892 // Set the field above. 893 void 894 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) { 895 _evac_failure_closure = evac_failure_closure; 896 } 897 898 // Push "obj" on the scan stack. 899 void push_on_evac_failure_scan_stack(oop obj); 900 // Process scan stack entries until the stack is empty. 901 void drain_evac_failure_scan_stack(); 902 // True iff an invocation of "drain_scan_stack" is in progress; to 903 // prevent unnecessary recursion. 904 bool _drain_in_progress; 905 906 // Do any necessary initialization for evacuation-failure handling. 907 // "cl" is the closure that will be used to process evac-failure 908 // objects. 909 void init_for_evac_failure(OopsInHeapRegionClosure* cl); 910 // Do any necessary cleanup for evacuation-failure handling data 911 // structures. 912 void finalize_for_evac_failure(); 913 914 // An attempt to evacuate "obj" has failed; take necessary steps. 915 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj); 916 void handle_evacuation_failure_common(oop obj, markOop m); 917 918 #ifndef PRODUCT 919 // Support for forcing evacuation failures. Analogous to 920 // PromotionFailureALot for the other collectors. 921 922 // Records whether G1EvacuationFailureALot should be in effect 923 // for the current GC 924 bool _evacuation_failure_alot_for_current_gc; 925 926 // Used to record the GC number for interval checking when 927 // determining whether G1EvaucationFailureALot is in effect 928 // for the current GC. 929 size_t _evacuation_failure_alot_gc_number; 930 931 // Count of the number of evacuations between failures. 932 volatile size_t _evacuation_failure_alot_count; 933 934 // Set whether G1EvacuationFailureALot should be in effect 935 // for the current GC (based upon the type of GC and which 936 // command line flags are set); 937 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 938 bool during_initial_mark, 939 bool during_marking); 940 941 inline void set_evacuation_failure_alot_for_current_gc(); 942 943 // Return true if it's time to cause an evacuation failure. 944 inline bool evacuation_should_fail(); 945 946 // Reset the G1EvacuationFailureALot counters. Should be called at 947 // the end of an evacuation pause in which an evacuation failure ocurred. 948 inline void reset_evacuation_should_fail(); 949 #endif // !PRODUCT 950 951 // ("Weak") Reference processing support. 952 // 953 // G1 has 2 instances of the referece processor class. One 954 // (_ref_processor_cm) handles reference object discovery 955 // and subsequent processing during concurrent marking cycles. 956 // 957 // The other (_ref_processor_stw) handles reference object 958 // discovery and processing during full GCs and incremental 959 // evacuation pauses. 960 // 961 // During an incremental pause, reference discovery will be 962 // temporarily disabled for _ref_processor_cm and will be 963 // enabled for _ref_processor_stw. At the end of the evacuation 964 // pause references discovered by _ref_processor_stw will be 965 // processed and discovery will be disabled. The previous 966 // setting for reference object discovery for _ref_processor_cm 967 // will be re-instated. 968 // 969 // At the start of marking: 970 // * Discovery by the CM ref processor is verified to be inactive 971 // and it's discovered lists are empty. 972 // * Discovery by the CM ref processor is then enabled. 973 // 974 // At the end of marking: 975 // * Any references on the CM ref processor's discovered 976 // lists are processed (possibly MT). 977 // 978 // At the start of full GC we: 979 // * Disable discovery by the CM ref processor and 980 // empty CM ref processor's discovered lists 981 // (without processing any entries). 982 // * Verify that the STW ref processor is inactive and it's 983 // discovered lists are empty. 984 // * Temporarily set STW ref processor discovery as single threaded. 985 // * Temporarily clear the STW ref processor's _is_alive_non_header 986 // field. 987 // * Finally enable discovery by the STW ref processor. 988 // 989 // The STW ref processor is used to record any discovered 990 // references during the full GC. 991 // 992 // At the end of a full GC we: 993 // * Enqueue any reference objects discovered by the STW ref processor 994 // that have non-live referents. This has the side-effect of 995 // making the STW ref processor inactive by disabling discovery. 996 // * Verify that the CM ref processor is still inactive 997 // and no references have been placed on it's discovered 998 // lists (also checked as a precondition during initial marking). 999 1000 // The (stw) reference processor... 1001 ReferenceProcessor* _ref_processor_stw; 1002 1003 // During reference object discovery, the _is_alive_non_header 1004 // closure (if non-null) is applied to the referent object to 1005 // determine whether the referent is live. If so then the 1006 // reference object does not need to be 'discovered' and can 1007 // be treated as a regular oop. This has the benefit of reducing 1008 // the number of 'discovered' reference objects that need to 1009 // be processed. 1010 // 1011 // Instance of the is_alive closure for embedding into the 1012 // STW reference processor as the _is_alive_non_header field. 1013 // Supplying a value for the _is_alive_non_header field is 1014 // optional but doing so prevents unnecessary additions to 1015 // the discovered lists during reference discovery. 1016 G1STWIsAliveClosure _is_alive_closure_stw; 1017 1018 // The (concurrent marking) reference processor... 1019 ReferenceProcessor* _ref_processor_cm; 1020 1021 // Instance of the concurrent mark is_alive closure for embedding 1022 // into the Concurrent Marking reference processor as the 1023 // _is_alive_non_header field. Supplying a value for the 1024 // _is_alive_non_header field is optional but doing so prevents 1025 // unnecessary additions to the discovered lists during reference 1026 // discovery. 1027 G1CMIsAliveClosure _is_alive_closure_cm; 1028 1029 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 1030 HeapRegion** _worker_cset_start_region; 1031 1032 // Time stamp to validate the regions recorded in the cache 1033 // used by G1CollectedHeap::start_cset_region_for_worker(). 1034 // The heap region entry for a given worker is valid iff 1035 // the associated time stamp value matches the current value 1036 // of G1CollectedHeap::_gc_time_stamp. 1037 unsigned int* _worker_cset_start_region_time_stamp; 1038 1039 enum G1H_process_strong_roots_tasks { 1040 G1H_PS_filter_satb_buffers, 1041 G1H_PS_refProcessor_oops_do, 1042 // Leave this one last. 1043 G1H_PS_NumElements 1044 }; 1045 1046 SubTasksDone* _process_strong_tasks; 1047 1048 volatile bool _free_regions_coming; 1049 1050 public: 1051 1052 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; } 1053 1054 void set_refine_cte_cl_concurrency(bool concurrent); 1055 1056 RefToScanQueue *task_queue(int i) const; 1057 1058 // A set of cards where updates happened during the GC 1059 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 1060 1061 // A DirtyCardQueueSet that is used to hold cards that contain 1062 // references into the current collection set. This is used to 1063 // update the remembered sets of the regions in the collection 1064 // set in the event of an evacuation failure. 1065 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 1066 { return _into_cset_dirty_card_queue_set; } 1067 1068 // Create a G1CollectedHeap with the specified policy. 1069 // Must call the initialize method afterwards. 1070 // May not return if something goes wrong. 1071 G1CollectedHeap(G1CollectorPolicy* policy); 1072 1073 // Initialize the G1CollectedHeap to have the initial and 1074 // maximum sizes and remembered and barrier sets 1075 // specified by the policy object. 1076 jint initialize(); 1077 1078 // Initialize weak reference processing. 1079 virtual void ref_processing_init(); 1080 1081 void set_par_threads(uint t) { 1082 SharedHeap::set_par_threads(t); 1083 // Done in SharedHeap but oddly there are 1084 // two _process_strong_tasks's in a G1CollectedHeap 1085 // so do it here too. 1086 _process_strong_tasks->set_n_threads(t); 1087 } 1088 1089 // Set _n_par_threads according to a policy TBD. 1090 void set_par_threads(); 1091 1092 void set_n_termination(int t) { 1093 _process_strong_tasks->set_n_threads(t); 1094 } 1095 1096 virtual CollectedHeap::Name kind() const { 1097 return CollectedHeap::G1CollectedHeap; 1098 } 1099 1100 // The current policy object for the collector. 1101 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1102 1103 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } 1104 1105 // Adaptive size policy. No such thing for g1. 1106 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1107 1108 // The rem set and barrier set. 1109 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1110 ModRefBarrierSet* mr_bs() const { return _mr_bs; } 1111 1112 unsigned get_gc_time_stamp() { 1113 return _gc_time_stamp; 1114 } 1115 1116 void reset_gc_time_stamp() { 1117 _gc_time_stamp = 0; 1118 OrderAccess::fence(); 1119 // Clear the cached CSet starting regions and time stamps. 1120 // Their validity is dependent on the GC timestamp. 1121 clear_cset_start_regions(); 1122 } 1123 1124 void check_gc_time_stamps() PRODUCT_RETURN; 1125 1126 void increment_gc_time_stamp() { 1127 ++_gc_time_stamp; 1128 OrderAccess::fence(); 1129 } 1130 1131 // Reset the given region's GC timestamp. If it's starts humongous, 1132 // also reset the GC timestamp of its corresponding 1133 // continues humongous regions too. 1134 void reset_gc_time_stamps(HeapRegion* hr); 1135 1136 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1137 DirtyCardQueue* into_cset_dcq, 1138 bool concurrent, int worker_i); 1139 1140 // The shared block offset table array. 1141 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1142 1143 // Reference Processing accessors 1144 1145 // The STW reference processor.... 1146 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1147 1148 // The Concurent Marking reference processor... 1149 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1150 1151 virtual size_t capacity() const; 1152 virtual size_t used() const; 1153 // This should be called when we're not holding the heap lock. The 1154 // result might be a bit inaccurate. 1155 size_t used_unlocked() const; 1156 size_t recalculate_used() const; 1157 1158 // These virtual functions do the actual allocation. 1159 // Some heaps may offer a contiguous region for shared non-blocking 1160 // allocation, via inlined code (by exporting the address of the top and 1161 // end fields defining the extent of the contiguous allocation region.) 1162 // But G1CollectedHeap doesn't yet support this. 1163 1164 // Return an estimate of the maximum allocation that could be performed 1165 // without triggering any collection or expansion activity. In a 1166 // generational collector, for example, this is probably the largest 1167 // allocation that could be supported (without expansion) in the youngest 1168 // generation. It is "unsafe" because no locks are taken; the result 1169 // should be treated as an approximation, not a guarantee, for use in 1170 // heuristic resizing decisions. 1171 virtual size_t unsafe_max_alloc(); 1172 1173 virtual bool is_maximal_no_gc() const { 1174 return _g1_storage.uncommitted_size() == 0; 1175 } 1176 1177 // The total number of regions in the heap. 1178 uint n_regions() { return _hrs.length(); } 1179 1180 // The max number of regions in the heap. 1181 uint max_regions() { return _hrs.max_length(); } 1182 1183 // The number of regions that are completely free. 1184 uint free_regions() { return _free_list.length(); } 1185 1186 // The number of regions that are not completely free. 1187 uint used_regions() { return n_regions() - free_regions(); } 1188 1189 // The number of regions available for "regular" expansion. 1190 uint expansion_regions() { return _expansion_regions; } 1191 1192 // Factory method for HeapRegion instances. It will return NULL if 1193 // the allocation fails. 1194 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom); 1195 1196 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1197 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1198 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1199 void verify_dirty_young_regions() PRODUCT_RETURN; 1200 1201 // verify_region_sets() performs verification over the region 1202 // lists. It will be compiled in the product code to be used when 1203 // necessary (i.e., during heap verification). 1204 void verify_region_sets(); 1205 1206 // verify_region_sets_optional() is planted in the code for 1207 // list verification in non-product builds (and it can be enabled in 1208 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1). 1209 #if HEAP_REGION_SET_FORCE_VERIFY 1210 void verify_region_sets_optional() { 1211 verify_region_sets(); 1212 } 1213 #else // HEAP_REGION_SET_FORCE_VERIFY 1214 void verify_region_sets_optional() { } 1215 #endif // HEAP_REGION_SET_FORCE_VERIFY 1216 1217 #ifdef ASSERT 1218 bool is_on_master_free_list(HeapRegion* hr) { 1219 return hr->containing_set() == &_free_list; 1220 } 1221 1222 bool is_in_humongous_set(HeapRegion* hr) { 1223 return hr->containing_set() == &_humongous_set; 1224 } 1225 #endif // ASSERT 1226 1227 // Wrapper for the region list operations that can be called from 1228 // methods outside this class. 1229 1230 void secondary_free_list_add_as_tail(FreeRegionList* list) { 1231 _secondary_free_list.add_as_tail(list); 1232 } 1233 1234 void append_secondary_free_list() { 1235 _free_list.add_as_head(&_secondary_free_list); 1236 } 1237 1238 void append_secondary_free_list_if_not_empty_with_lock() { 1239 // If the secondary free list looks empty there's no reason to 1240 // take the lock and then try to append it. 1241 if (!_secondary_free_list.is_empty()) { 1242 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1243 append_secondary_free_list(); 1244 } 1245 } 1246 1247 void old_set_remove(HeapRegion* hr) { 1248 _old_set.remove(hr); 1249 } 1250 1251 size_t non_young_capacity_bytes() { 1252 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1253 } 1254 1255 void set_free_regions_coming(); 1256 void reset_free_regions_coming(); 1257 bool free_regions_coming() { return _free_regions_coming; } 1258 void wait_while_free_regions_coming(); 1259 1260 // Determine whether the given region is one that we are using as an 1261 // old GC alloc region. 1262 bool is_old_gc_alloc_region(HeapRegion* hr) { 1263 return hr == _retained_old_gc_alloc_region; 1264 } 1265 1266 // Perform a collection of the heap; intended for use in implementing 1267 // "System.gc". This probably implies as full a collection as the 1268 // "CollectedHeap" supports. 1269 virtual void collect(GCCause::Cause cause); 1270 1271 // The same as above but assume that the caller holds the Heap_lock. 1272 void collect_locked(GCCause::Cause cause); 1273 1274 // True iff a evacuation has failed in the most-recent collection. 1275 bool evacuation_failed() { return _evacuation_failed; } 1276 1277 // It will free a region if it has allocated objects in it that are 1278 // all dead. It calls either free_region() or 1279 // free_humongous_region() depending on the type of the region that 1280 // is passed to it. 1281 void free_region_if_empty(HeapRegion* hr, 1282 size_t* pre_used, 1283 FreeRegionList* free_list, 1284 OldRegionSet* old_proxy_set, 1285 HumongousRegionSet* humongous_proxy_set, 1286 HRRSCleanupTask* hrrs_cleanup_task, 1287 bool par); 1288 1289 // It appends the free list to the master free list and updates the 1290 // master humongous list according to the contents of the proxy 1291 // list. It also adjusts the total used bytes according to pre_used 1292 // (if par is true, it will do so by taking the ParGCRareEvent_lock). 1293 void update_sets_after_freeing_regions(size_t pre_used, 1294 FreeRegionList* free_list, 1295 OldRegionSet* old_proxy_set, 1296 HumongousRegionSet* humongous_proxy_set, 1297 bool par); 1298 1299 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1300 virtual bool is_in(const void* p) const; 1301 1302 // Return "TRUE" iff the given object address is within the collection 1303 // set. 1304 inline bool obj_in_cs(oop obj); 1305 1306 // Return "TRUE" iff the given object address is in the reserved 1307 // region of g1. 1308 bool is_in_g1_reserved(const void* p) const { 1309 return _g1_reserved.contains(p); 1310 } 1311 1312 // Returns a MemRegion that corresponds to the space that has been 1313 // reserved for the heap 1314 MemRegion g1_reserved() { 1315 return _g1_reserved; 1316 } 1317 1318 // Returns a MemRegion that corresponds to the space that has been 1319 // committed in the heap 1320 MemRegion g1_committed() { 1321 return _g1_committed; 1322 } 1323 1324 virtual bool is_in_closed_subset(const void* p) const; 1325 1326 // This resets the card table to all zeros. It is used after 1327 // a collection pause which used the card table to claim cards. 1328 void cleanUpCardTable(); 1329 1330 // Iteration functions. 1331 1332 // Iterate over all the ref-containing fields of all objects, calling 1333 // "cl.do_oop" on each. 1334 virtual void oop_iterate(ExtendedOopClosure* cl); 1335 1336 // Same as above, restricted to a memory region. 1337 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl); 1338 1339 // Iterate over all objects, calling "cl.do_object" on each. 1340 virtual void object_iterate(ObjectClosure* cl); 1341 1342 virtual void safe_object_iterate(ObjectClosure* cl) { 1343 object_iterate(cl); 1344 } 1345 1346 // Iterate over all objects allocated since the last collection, calling 1347 // "cl.do_object" on each. The heap must have been initialized properly 1348 // to support this function, or else this call will fail. 1349 virtual void object_iterate_since_last_GC(ObjectClosure* cl); 1350 1351 // Iterate over all spaces in use in the heap, in ascending address order. 1352 virtual void space_iterate(SpaceClosure* cl); 1353 1354 // Iterate over heap regions, in address order, terminating the 1355 // iteration early if the "doHeapRegion" method returns "true". 1356 void heap_region_iterate(HeapRegionClosure* blk) const; 1357 1358 // Return the region with the given index. It assumes the index is valid. 1359 HeapRegion* region_at(uint index) const { return _hrs.at(index); } 1360 1361 // Divide the heap region sequence into "chunks" of some size (the number 1362 // of regions divided by the number of parallel threads times some 1363 // overpartition factor, currently 4). Assumes that this will be called 1364 // in parallel by ParallelGCThreads worker threads with discinct worker 1365 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel 1366 // calls will use the same "claim_value", and that that claim value is 1367 // different from the claim_value of any heap region before the start of 1368 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by 1369 // attempting to claim the first region in each chunk, and, if 1370 // successful, applying the closure to each region in the chunk (and 1371 // setting the claim value of the second and subsequent regions of the 1372 // chunk.) For now requires that "doHeapRegion" always returns "false", 1373 // i.e., that a closure never attempt to abort a traversal. 1374 void heap_region_par_iterate_chunked(HeapRegionClosure* blk, 1375 uint worker, 1376 uint no_of_par_workers, 1377 jint claim_value); 1378 1379 // It resets all the region claim values to the default. 1380 void reset_heap_region_claim_values(); 1381 1382 // Resets the claim values of regions in the current 1383 // collection set to the default. 1384 void reset_cset_heap_region_claim_values(); 1385 1386 #ifdef ASSERT 1387 bool check_heap_region_claim_values(jint claim_value); 1388 1389 // Same as the routine above but only checks regions in the 1390 // current collection set. 1391 bool check_cset_heap_region_claim_values(jint claim_value); 1392 #endif // ASSERT 1393 1394 // Clear the cached cset start regions and (more importantly) 1395 // the time stamps. Called when we reset the GC time stamp. 1396 void clear_cset_start_regions(); 1397 1398 // Given the id of a worker, obtain or calculate a suitable 1399 // starting region for iterating over the current collection set. 1400 HeapRegion* start_cset_region_for_worker(int worker_i); 1401 1402 // This is a convenience method that is used by the 1403 // HeapRegionIterator classes to calculate the starting region for 1404 // each worker so that they do not all start from the same region. 1405 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers); 1406 1407 // Iterate over the regions (if any) in the current collection set. 1408 void collection_set_iterate(HeapRegionClosure* blk); 1409 1410 // As above but starting from region r 1411 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1412 1413 // Returns the first (lowest address) compactible space in the heap. 1414 virtual CompactibleSpace* first_compactible_space(); 1415 1416 // A CollectedHeap will contain some number of spaces. This finds the 1417 // space containing a given address, or else returns NULL. 1418 virtual Space* space_containing(const void* addr) const; 1419 1420 // A G1CollectedHeap will contain some number of heap regions. This 1421 // finds the region containing a given address, or else returns NULL. 1422 template <class T> 1423 inline HeapRegion* heap_region_containing(const T addr) const; 1424 1425 // Like the above, but requires "addr" to be in the heap (to avoid a 1426 // null-check), and unlike the above, may return an continuing humongous 1427 // region. 1428 template <class T> 1429 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1430 1431 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1432 // each address in the (reserved) heap is a member of exactly 1433 // one block. The defining characteristic of a block is that it is 1434 // possible to find its size, and thus to progress forward to the next 1435 // block. (Blocks may be of different sizes.) Thus, blocks may 1436 // represent Java objects, or they might be free blocks in a 1437 // free-list-based heap (or subheap), as long as the two kinds are 1438 // distinguishable and the size of each is determinable. 1439 1440 // Returns the address of the start of the "block" that contains the 1441 // address "addr". We say "blocks" instead of "object" since some heaps 1442 // may not pack objects densely; a chunk may either be an object or a 1443 // non-object. 1444 virtual HeapWord* block_start(const void* addr) const; 1445 1446 // Requires "addr" to be the start of a chunk, and returns its size. 1447 // "addr + size" is required to be the start of a new chunk, or the end 1448 // of the active area of the heap. 1449 virtual size_t block_size(const HeapWord* addr) const; 1450 1451 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1452 // the block is an object. 1453 virtual bool block_is_obj(const HeapWord* addr) const; 1454 1455 // Does this heap support heap inspection? (+PrintClassHistogram) 1456 virtual bool supports_heap_inspection() const { return true; } 1457 1458 // Section on thread-local allocation buffers (TLABs) 1459 // See CollectedHeap for semantics. 1460 1461 virtual bool supports_tlab_allocation() const; 1462 virtual size_t tlab_capacity(Thread* thr) const; 1463 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const; 1464 1465 // Can a compiler initialize a new object without store barriers? 1466 // This permission only extends from the creation of a new object 1467 // via a TLAB up to the first subsequent safepoint. If such permission 1468 // is granted for this heap type, the compiler promises to call 1469 // defer_store_barrier() below on any slow path allocation of 1470 // a new object for which such initializing store barriers will 1471 // have been elided. G1, like CMS, allows this, but should be 1472 // ready to provide a compensating write barrier as necessary 1473 // if that storage came out of a non-young region. The efficiency 1474 // of this implementation depends crucially on being able to 1475 // answer very efficiently in constant time whether a piece of 1476 // storage in the heap comes from a young region or not. 1477 // See ReduceInitialCardMarks. 1478 virtual bool can_elide_tlab_store_barriers() const { 1479 return true; 1480 } 1481 1482 virtual bool card_mark_must_follow_store() const { 1483 return true; 1484 } 1485 1486 bool is_in_young(const oop obj) { 1487 HeapRegion* hr = heap_region_containing(obj); 1488 return hr != NULL && hr->is_young(); 1489 } 1490 1491 #ifdef ASSERT 1492 virtual bool is_in_partial_collection(const void* p); 1493 #endif 1494 1495 virtual bool is_scavengable(const void* addr); 1496 1497 // We don't need barriers for initializing stores to objects 1498 // in the young gen: for the SATB pre-barrier, there is no 1499 // pre-value that needs to be remembered; for the remembered-set 1500 // update logging post-barrier, we don't maintain remembered set 1501 // information for young gen objects. 1502 virtual bool can_elide_initializing_store_barrier(oop new_obj) { 1503 return is_in_young(new_obj); 1504 } 1505 1506 // Returns "true" iff the given word_size is "very large". 1507 static bool isHumongous(size_t word_size) { 1508 // Note this has to be strictly greater-than as the TLABs 1509 // are capped at the humongous thresold and we want to 1510 // ensure that we don't try to allocate a TLAB as 1511 // humongous and that we don't allocate a humongous 1512 // object in a TLAB. 1513 return word_size > _humongous_object_threshold_in_words; 1514 } 1515 1516 // Update mod union table with the set of dirty cards. 1517 void updateModUnion(); 1518 1519 // Set the mod union bits corresponding to the given memRegion. Note 1520 // that this is always a safe operation, since it doesn't clear any 1521 // bits. 1522 void markModUnionRange(MemRegion mr); 1523 1524 // Records the fact that a marking phase is no longer in progress. 1525 void set_marking_complete() { 1526 _mark_in_progress = false; 1527 } 1528 void set_marking_started() { 1529 _mark_in_progress = true; 1530 } 1531 bool mark_in_progress() { 1532 return _mark_in_progress; 1533 } 1534 1535 // Print the maximum heap capacity. 1536 virtual size_t max_capacity() const; 1537 1538 virtual jlong millis_since_last_gc(); 1539 1540 // Perform any cleanup actions necessary before allowing a verification. 1541 virtual void prepare_for_verify(); 1542 1543 // Perform verification. 1544 1545 // vo == UsePrevMarking -> use "prev" marking information, 1546 // vo == UseNextMarking -> use "next" marking information 1547 // vo == UseMarkWord -> use the mark word in the object header 1548 // 1549 // NOTE: Only the "prev" marking information is guaranteed to be 1550 // consistent most of the time, so most calls to this should use 1551 // vo == UsePrevMarking. 1552 // Currently, there is only one case where this is called with 1553 // vo == UseNextMarking, which is to verify the "next" marking 1554 // information at the end of remark. 1555 // Currently there is only one place where this is called with 1556 // vo == UseMarkWord, which is to verify the marking during a 1557 // full GC. 1558 void verify(bool silent, VerifyOption vo); 1559 1560 // Override; it uses the "prev" marking information 1561 virtual void verify(bool silent); 1562 virtual void print_on(outputStream* st) const; 1563 virtual void print_extended_on(outputStream* st) const; 1564 virtual void print_on_error(outputStream* st) const; 1565 1566 virtual void print_gc_threads_on(outputStream* st) const; 1567 virtual void gc_threads_do(ThreadClosure* tc) const; 1568 1569 // Override 1570 void print_tracing_info() const; 1571 1572 // The following two methods are helpful for debugging RSet issues. 1573 void print_cset_rsets() PRODUCT_RETURN; 1574 void print_all_rsets() PRODUCT_RETURN; 1575 1576 // Convenience function to be used in situations where the heap type can be 1577 // asserted to be this type. 1578 static G1CollectedHeap* heap(); 1579 1580 void set_region_short_lived_locked(HeapRegion* hr); 1581 // add appropriate methods for any other surv rate groups 1582 1583 YoungList* young_list() { return _young_list; } 1584 1585 // debugging 1586 bool check_young_list_well_formed() { 1587 return _young_list->check_list_well_formed(); 1588 } 1589 1590 bool check_young_list_empty(bool check_heap, 1591 bool check_sample = true); 1592 1593 // *** Stuff related to concurrent marking. It's not clear to me that so 1594 // many of these need to be public. 1595 1596 // The functions below are helper functions that a subclass of 1597 // "CollectedHeap" can use in the implementation of its virtual 1598 // functions. 1599 // This performs a concurrent marking of the live objects in a 1600 // bitmap off to the side. 1601 void doConcurrentMark(); 1602 1603 bool isMarkedPrev(oop obj) const; 1604 bool isMarkedNext(oop obj) const; 1605 1606 // Determine if an object is dead, given the object and also 1607 // the region to which the object belongs. An object is dead 1608 // iff a) it was not allocated since the last mark and b) it 1609 // is not marked. 1610 1611 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1612 return 1613 !hr->obj_allocated_since_prev_marking(obj) && 1614 !isMarkedPrev(obj); 1615 } 1616 1617 // This function returns true when an object has been 1618 // around since the previous marking and hasn't yet 1619 // been marked during this marking. 1620 1621 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1622 return 1623 !hr->obj_allocated_since_next_marking(obj) && 1624 !isMarkedNext(obj); 1625 } 1626 1627 // Determine if an object is dead, given only the object itself. 1628 // This will find the region to which the object belongs and 1629 // then call the region version of the same function. 1630 1631 // Added if it is NULL it isn't dead. 1632 1633 bool is_obj_dead(const oop obj) const { 1634 const HeapRegion* hr = heap_region_containing(obj); 1635 if (hr == NULL) { 1636 if (obj == NULL) return false; 1637 else return true; 1638 } 1639 else return is_obj_dead(obj, hr); 1640 } 1641 1642 bool is_obj_ill(const oop obj) const { 1643 const HeapRegion* hr = heap_region_containing(obj); 1644 if (hr == NULL) { 1645 if (obj == NULL) return false; 1646 else return true; 1647 } 1648 else return is_obj_ill(obj, hr); 1649 } 1650 1651 // The methods below are here for convenience and dispatch the 1652 // appropriate method depending on value of the given VerifyOption 1653 // parameter. The options for that parameter are: 1654 // 1655 // vo == UsePrevMarking -> use "prev" marking information, 1656 // vo == UseNextMarking -> use "next" marking information, 1657 // vo == UseMarkWord -> use mark word from object header 1658 1659 bool is_obj_dead_cond(const oop obj, 1660 const HeapRegion* hr, 1661 const VerifyOption vo) const { 1662 switch (vo) { 1663 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 1664 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 1665 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 1666 default: ShouldNotReachHere(); 1667 } 1668 return false; // keep some compilers happy 1669 } 1670 1671 bool is_obj_dead_cond(const oop obj, 1672 const VerifyOption vo) const { 1673 switch (vo) { 1674 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 1675 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 1676 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 1677 default: ShouldNotReachHere(); 1678 } 1679 return false; // keep some compilers happy 1680 } 1681 1682 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1683 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1684 bool is_marked(oop obj, VerifyOption vo); 1685 const char* top_at_mark_start_str(VerifyOption vo); 1686 1687 // The following is just to alert the verification code 1688 // that a full collection has occurred and that the 1689 // remembered sets are no longer up to date. 1690 bool _full_collection; 1691 void set_full_collection() { _full_collection = true;} 1692 void clear_full_collection() {_full_collection = false;} 1693 bool full_collection() {return _full_collection;} 1694 1695 ConcurrentMark* concurrent_mark() const { return _cm; } 1696 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1697 1698 // The dirty cards region list is used to record a subset of regions 1699 // whose cards need clearing. The list if populated during the 1700 // remembered set scanning and drained during the card table 1701 // cleanup. Although the methods are reentrant, population/draining 1702 // phases must not overlap. For synchronization purposes the last 1703 // element on the list points to itself. 1704 HeapRegion* _dirty_cards_region_list; 1705 void push_dirty_cards_region(HeapRegion* hr); 1706 HeapRegion* pop_dirty_cards_region(); 1707 1708 public: 1709 void stop_conc_gc_threads(); 1710 1711 size_t pending_card_num(); 1712 size_t cards_scanned(); 1713 1714 protected: 1715 size_t _max_heap_capacity; 1716 }; 1717 1718 class G1ParGCAllocBuffer: public ParGCAllocBuffer { 1719 private: 1720 bool _retired; 1721 1722 public: 1723 G1ParGCAllocBuffer(size_t gclab_word_size); 1724 1725 void set_buf(HeapWord* buf) { 1726 ParGCAllocBuffer::set_buf(buf); 1727 _retired = false; 1728 } 1729 1730 void retire(bool end_of_gc, bool retain) { 1731 if (_retired) 1732 return; 1733 ParGCAllocBuffer::retire(end_of_gc, retain); 1734 _retired = true; 1735 } 1736 }; 1737 1738 class G1ParScanThreadState : public StackObj { 1739 protected: 1740 G1CollectedHeap* _g1h; 1741 RefToScanQueue* _refs; 1742 DirtyCardQueue _dcq; 1743 CardTableModRefBS* _ct_bs; 1744 G1RemSet* _g1_rem; 1745 1746 G1ParGCAllocBuffer _surviving_alloc_buffer; 1747 G1ParGCAllocBuffer _tenured_alloc_buffer; 1748 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount]; 1749 ageTable _age_table; 1750 1751 size_t _alloc_buffer_waste; 1752 size_t _undo_waste; 1753 1754 OopsInHeapRegionClosure* _evac_failure_cl; 1755 G1ParScanHeapEvacClosure* _evac_cl; 1756 G1ParScanPartialArrayClosure* _partial_scan_cl; 1757 1758 int _hash_seed; 1759 uint _queue_num; 1760 1761 size_t _term_attempts; 1762 1763 double _start; 1764 double _start_strong_roots; 1765 double _strong_roots_time; 1766 double _start_term; 1767 double _term_time; 1768 1769 // Map from young-age-index (0 == not young, 1 is youngest) to 1770 // surviving words. base is what we get back from the malloc call 1771 size_t* _surviving_young_words_base; 1772 // this points into the array, as we use the first few entries for padding 1773 size_t* _surviving_young_words; 1774 1775 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t)) 1776 1777 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; } 1778 1779 void add_to_undo_waste(size_t waste) { _undo_waste += waste; } 1780 1781 DirtyCardQueue& dirty_card_queue() { return _dcq; } 1782 CardTableModRefBS* ctbs() { return _ct_bs; } 1783 1784 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) { 1785 if (!from->is_survivor()) { 1786 _g1_rem->par_write_ref(from, p, tid); 1787 } 1788 } 1789 1790 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) { 1791 // If the new value of the field points to the same region or 1792 // is the to-space, we don't need to include it in the Rset updates. 1793 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) { 1794 size_t card_index = ctbs()->index_for(p); 1795 // If the card hasn't been added to the buffer, do it. 1796 if (ctbs()->mark_card_deferred(card_index)) { 1797 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index)); 1798 } 1799 } 1800 } 1801 1802 public: 1803 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num); 1804 1805 ~G1ParScanThreadState() { 1806 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC); 1807 } 1808 1809 RefToScanQueue* refs() { return _refs; } 1810 ageTable* age_table() { return &_age_table; } 1811 1812 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) { 1813 return _alloc_buffers[purpose]; 1814 } 1815 1816 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; } 1817 size_t undo_waste() const { return _undo_waste; } 1818 1819 #ifdef ASSERT 1820 bool verify_ref(narrowOop* ref) const; 1821 bool verify_ref(oop* ref) const; 1822 bool verify_task(StarTask ref) const; 1823 #endif // ASSERT 1824 1825 template <class T> void push_on_queue(T* ref) { 1826 assert(verify_ref(ref), "sanity"); 1827 refs()->push(ref); 1828 } 1829 1830 template <class T> void update_rs(HeapRegion* from, T* p, int tid) { 1831 if (G1DeferredRSUpdate) { 1832 deferred_rs_update(from, p, tid); 1833 } else { 1834 immediate_rs_update(from, p, tid); 1835 } 1836 } 1837 1838 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) { 1839 HeapWord* obj = NULL; 1840 size_t gclab_word_size = _g1h->desired_plab_sz(purpose); 1841 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) { 1842 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose); 1843 add_to_alloc_buffer_waste(alloc_buf->words_remaining()); 1844 alloc_buf->retire(false /* end_of_gc */, false /* retain */); 1845 1846 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size); 1847 if (buf == NULL) return NULL; // Let caller handle allocation failure. 1848 // Otherwise. 1849 alloc_buf->set_word_size(gclab_word_size); 1850 alloc_buf->set_buf(buf); 1851 1852 obj = alloc_buf->allocate(word_sz); 1853 assert(obj != NULL, "buffer was definitely big enough..."); 1854 } else { 1855 obj = _g1h->par_allocate_during_gc(purpose, word_sz); 1856 } 1857 return obj; 1858 } 1859 1860 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) { 1861 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz); 1862 if (obj != NULL) return obj; 1863 return allocate_slow(purpose, word_sz); 1864 } 1865 1866 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) { 1867 if (alloc_buffer(purpose)->contains(obj)) { 1868 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1), 1869 "should contain whole object"); 1870 alloc_buffer(purpose)->undo_allocation(obj, word_sz); 1871 } else { 1872 CollectedHeap::fill_with_object(obj, word_sz); 1873 add_to_undo_waste(word_sz); 1874 } 1875 } 1876 1877 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) { 1878 _evac_failure_cl = evac_failure_cl; 1879 } 1880 OopsInHeapRegionClosure* evac_failure_closure() { 1881 return _evac_failure_cl; 1882 } 1883 1884 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) { 1885 _evac_cl = evac_cl; 1886 } 1887 1888 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) { 1889 _partial_scan_cl = partial_scan_cl; 1890 } 1891 1892 int* hash_seed() { return &_hash_seed; } 1893 uint queue_num() { return _queue_num; } 1894 1895 size_t term_attempts() const { return _term_attempts; } 1896 void note_term_attempt() { _term_attempts++; } 1897 1898 void start_strong_roots() { 1899 _start_strong_roots = os::elapsedTime(); 1900 } 1901 void end_strong_roots() { 1902 _strong_roots_time += (os::elapsedTime() - _start_strong_roots); 1903 } 1904 double strong_roots_time() const { return _strong_roots_time; } 1905 1906 void start_term_time() { 1907 note_term_attempt(); 1908 _start_term = os::elapsedTime(); 1909 } 1910 void end_term_time() { 1911 _term_time += (os::elapsedTime() - _start_term); 1912 } 1913 double term_time() const { return _term_time; } 1914 1915 double elapsed_time() const { 1916 return os::elapsedTime() - _start; 1917 } 1918 1919 static void 1920 print_termination_stats_hdr(outputStream* const st = gclog_or_tty); 1921 void 1922 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const; 1923 1924 size_t* surviving_young_words() { 1925 // We add on to hide entry 0 which accumulates surviving words for 1926 // age -1 regions (i.e. non-young ones) 1927 return _surviving_young_words; 1928 } 1929 1930 void retire_alloc_buffers() { 1931 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) { 1932 size_t waste = _alloc_buffers[ap]->words_remaining(); 1933 add_to_alloc_buffer_waste(waste); 1934 _alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap), 1935 true /* end_of_gc */, 1936 false /* retain */); 1937 } 1938 } 1939 1940 template <class T> void deal_with_reference(T* ref_to_scan) { 1941 if (has_partial_array_mask(ref_to_scan)) { 1942 _partial_scan_cl->do_oop_nv(ref_to_scan); 1943 } else { 1944 // Note: we can use "raw" versions of "region_containing" because 1945 // "obj_to_scan" is definitely in the heap, and is not in a 1946 // humongous region. 1947 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan); 1948 _evac_cl->set_region(r); 1949 _evac_cl->do_oop_nv(ref_to_scan); 1950 } 1951 } 1952 1953 void deal_with_reference(StarTask ref) { 1954 assert(verify_task(ref), "sanity"); 1955 if (ref.is_narrow()) { 1956 deal_with_reference((narrowOop*)ref); 1957 } else { 1958 deal_with_reference((oop*)ref); 1959 } 1960 } 1961 1962 public: 1963 void trim_queue(); 1964 }; 1965 1966 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP