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 void do_object(oop p) { assert(false, "Do not call."); } 169 bool do_object_b(oop p); 170 }; 171 172 class SurvivorGCAllocRegion : public G1AllocRegion { 173 protected: 174 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 175 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 176 public: 177 SurvivorGCAllocRegion() 178 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { } 179 }; 180 181 class OldGCAllocRegion : public G1AllocRegion { 182 protected: 183 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 184 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 185 public: 186 OldGCAllocRegion() 187 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { } 188 }; 189 190 class RefineCardTableEntryClosure; 191 192 class G1CollectedHeap : public SharedHeap { 193 friend class VM_G1CollectForAllocation; 194 friend class VM_G1CollectFull; 195 friend class VM_G1IncCollectionPause; 196 friend class VMStructs; 197 friend class MutatorAllocRegion; 198 friend class SurvivorGCAllocRegion; 199 friend class OldGCAllocRegion; 200 201 // Closures used in implementation. 202 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object> 203 friend class G1ParCopyClosure; 204 friend class G1IsAliveClosure; 205 friend class G1EvacuateFollowersClosure; 206 friend class G1ParScanThreadState; 207 friend class G1ParScanClosureSuper; 208 friend class G1ParEvacuateFollowersClosure; 209 friend class G1ParTask; 210 friend class G1FreeGarbageRegionClosure; 211 friend class RefineCardTableEntryClosure; 212 friend class G1PrepareCompactClosure; 213 friend class RegionSorter; 214 friend class RegionResetter; 215 friend class CountRCClosure; 216 friend class EvacPopObjClosure; 217 friend class G1ParCleanupCTTask; 218 219 // Other related classes. 220 friend class G1MarkSweep; 221 222 private: 223 // The one and only G1CollectedHeap, so static functions can find it. 224 static G1CollectedHeap* _g1h; 225 226 static size_t _humongous_object_threshold_in_words; 227 228 // Storage for the G1 heap. 229 VirtualSpace _g1_storage; 230 MemRegion _g1_reserved; 231 232 // The part of _g1_storage that is currently committed. 233 MemRegion _g1_committed; 234 235 // The master free list. It will satisfy all new region allocations. 236 MasterFreeRegionList _free_list; 237 238 // The secondary free list which contains regions that have been 239 // freed up during the cleanup process. This will be appended to the 240 // master free list when appropriate. 241 SecondaryFreeRegionList _secondary_free_list; 242 243 // It keeps track of the old regions. 244 MasterOldRegionSet _old_set; 245 246 // It keeps track of the humongous regions. 247 MasterHumongousRegionSet _humongous_set; 248 249 // The number of regions we could create by expansion. 250 uint _expansion_regions; 251 252 // The block offset table for the G1 heap. 253 G1BlockOffsetSharedArray* _bot_shared; 254 255 // Tears down the region sets / lists so that they are empty and the 256 // regions on the heap do not belong to a region set / list. The 257 // only exception is the humongous set which we leave unaltered. If 258 // free_list_only is true, it will only tear down the master free 259 // list. It is called before a Full GC (free_list_only == false) or 260 // before heap shrinking (free_list_only == true). 261 void tear_down_region_sets(bool free_list_only); 262 263 // Rebuilds the region sets / lists so that they are repopulated to 264 // reflect the contents of the heap. The only exception is the 265 // humongous set which was not torn down in the first place. If 266 // free_list_only is true, it will only rebuild the master free 267 // list. It is called after a Full GC (free_list_only == false) or 268 // after heap shrinking (free_list_only == true). 269 void rebuild_region_sets(bool free_list_only); 270 271 // The sequence of all heap regions in the heap. 272 HeapRegionSeq _hrs; 273 274 // Alloc region used to satisfy mutator allocation requests. 275 MutatorAllocRegion _mutator_alloc_region; 276 277 // Alloc region used to satisfy allocation requests by the GC for 278 // survivor objects. 279 SurvivorGCAllocRegion _survivor_gc_alloc_region; 280 281 // PLAB sizing policy for survivors. 282 PLABStats _survivor_plab_stats; 283 284 // Alloc region used to satisfy allocation requests by the GC for 285 // old objects. 286 OldGCAllocRegion _old_gc_alloc_region; 287 288 // PLAB sizing policy for tenured objects. 289 PLABStats _old_plab_stats; 290 291 PLABStats* stats_for_purpose(GCAllocPurpose purpose) { 292 PLABStats* stats = NULL; 293 294 switch (purpose) { 295 case GCAllocForSurvived: 296 stats = &_survivor_plab_stats; 297 break; 298 case GCAllocForTenured: 299 stats = &_old_plab_stats; 300 break; 301 default: 302 assert(false, "unrecognized GCAllocPurpose"); 303 } 304 305 return stats; 306 } 307 308 // The last old region we allocated to during the last GC. 309 // Typically, it is not full so we should re-use it during the next GC. 310 HeapRegion* _retained_old_gc_alloc_region; 311 312 // It specifies whether we should attempt to expand the heap after a 313 // region allocation failure. If heap expansion fails we set this to 314 // false so that we don't re-attempt the heap expansion (it's likely 315 // that subsequent expansion attempts will also fail if one fails). 316 // Currently, it is only consulted during GC and it's reset at the 317 // start of each GC. 318 bool _expand_heap_after_alloc_failure; 319 320 // It resets the mutator alloc region before new allocations can take place. 321 void init_mutator_alloc_region(); 322 323 // It releases the mutator alloc region. 324 void release_mutator_alloc_region(); 325 326 // It initializes the GC alloc regions at the start of a GC. 327 void init_gc_alloc_regions(); 328 329 // It releases the GC alloc regions at the end of a GC. 330 void release_gc_alloc_regions(uint no_of_gc_workers); 331 332 // It does any cleanup that needs to be done on the GC alloc regions 333 // before a Full GC. 334 void abandon_gc_alloc_regions(); 335 336 // Helper for monitoring and management support. 337 G1MonitoringSupport* _g1mm; 338 339 // Determines PLAB size for a particular allocation purpose. 340 size_t desired_plab_sz(GCAllocPurpose purpose); 341 342 // Outside of GC pauses, the number of bytes used in all regions other 343 // than the current allocation region. 344 size_t _summary_bytes_used; 345 346 // This is used for a quick test on whether a reference points into 347 // the collection set or not. Basically, we have an array, with one 348 // byte per region, and that byte denotes whether the corresponding 349 // region is in the collection set or not. The entry corresponding 350 // the bottom of the heap, i.e., region 0, is pointed to by 351 // _in_cset_fast_test_base. The _in_cset_fast_test field has been 352 // biased so that it actually points to address 0 of the address 353 // space, to make the test as fast as possible (we can simply shift 354 // the address to address into it, instead of having to subtract the 355 // bottom of the heap from the address before shifting it; basically 356 // it works in the same way the card table works). 357 bool* _in_cset_fast_test; 358 359 // The allocated array used for the fast test on whether a reference 360 // points into the collection set or not. This field is also used to 361 // free the array. 362 bool* _in_cset_fast_test_base; 363 364 // The length of the _in_cset_fast_test_base array. 365 uint _in_cset_fast_test_length; 366 367 volatile unsigned _gc_time_stamp; 368 369 size_t* _surviving_young_words; 370 371 G1HRPrinter _hr_printer; 372 373 void setup_surviving_young_words(); 374 void update_surviving_young_words(size_t* surv_young_words); 375 void cleanup_surviving_young_words(); 376 377 // It decides whether an explicit GC should start a concurrent cycle 378 // instead of doing a STW GC. Currently, a concurrent cycle is 379 // explicitly started if: 380 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 381 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 382 // (c) cause == _g1_humongous_allocation 383 bool should_do_concurrent_full_gc(GCCause::Cause cause); 384 385 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 386 // concurrent cycles) we have started. 387 volatile unsigned int _old_marking_cycles_started; 388 389 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 390 // concurrent cycles) we have completed. 391 volatile unsigned int _old_marking_cycles_completed; 392 393 // This is a non-product method that is helpful for testing. It is 394 // called at the end of a GC and artificially expands the heap by 395 // allocating a number of dead regions. This way we can induce very 396 // frequent marking cycles and stress the cleanup / concurrent 397 // cleanup code more (as all the regions that will be allocated by 398 // this method will be found dead by the marking cycle). 399 void allocate_dummy_regions() PRODUCT_RETURN; 400 401 // Clear RSets after a compaction. It also resets the GC time stamps. 402 void clear_rsets_post_compaction(); 403 404 // If the HR printer is active, dump the state of the regions in the 405 // heap after a compaction. 406 void print_hrs_post_compaction(); 407 408 double verify(bool guard, const char* msg); 409 void verify_before_gc(); 410 void verify_after_gc(); 411 412 void log_gc_header(); 413 void log_gc_footer(double pause_time_sec); 414 415 // These are macros so that, if the assert fires, we get the correct 416 // line number, file, etc. 417 418 #define heap_locking_asserts_err_msg(_extra_message_) \ 419 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 420 (_extra_message_), \ 421 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 422 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 423 BOOL_TO_STR(Thread::current()->is_VM_thread())) 424 425 #define assert_heap_locked() \ 426 do { \ 427 assert(Heap_lock->owned_by_self(), \ 428 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \ 429 } while (0) 430 431 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 432 do { \ 433 assert(Heap_lock->owned_by_self() || \ 434 (SafepointSynchronize::is_at_safepoint() && \ 435 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 436 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \ 437 "should be at a safepoint")); \ 438 } while (0) 439 440 #define assert_heap_locked_and_not_at_safepoint() \ 441 do { \ 442 assert(Heap_lock->owned_by_self() && \ 443 !SafepointSynchronize::is_at_safepoint(), \ 444 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \ 445 "should not be at a safepoint")); \ 446 } while (0) 447 448 #define assert_heap_not_locked() \ 449 do { \ 450 assert(!Heap_lock->owned_by_self(), \ 451 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \ 452 } while (0) 453 454 #define assert_heap_not_locked_and_not_at_safepoint() \ 455 do { \ 456 assert(!Heap_lock->owned_by_self() && \ 457 !SafepointSynchronize::is_at_safepoint(), \ 458 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \ 459 "should not be at a safepoint")); \ 460 } while (0) 461 462 #define assert_at_safepoint(_should_be_vm_thread_) \ 463 do { \ 464 assert(SafepointSynchronize::is_at_safepoint() && \ 465 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 466 heap_locking_asserts_err_msg("should be at a safepoint")); \ 467 } while (0) 468 469 #define assert_not_at_safepoint() \ 470 do { \ 471 assert(!SafepointSynchronize::is_at_safepoint(), \ 472 heap_locking_asserts_err_msg("should not be at a safepoint")); \ 473 } while (0) 474 475 protected: 476 477 // The young region list. 478 YoungList* _young_list; 479 480 // The current policy object for the collector. 481 G1CollectorPolicy* _g1_policy; 482 483 // This is the second level of trying to allocate a new region. If 484 // new_region() didn't find a region on the free_list, this call will 485 // check whether there's anything available on the 486 // secondary_free_list and/or wait for more regions to appear on 487 // that list, if _free_regions_coming is set. 488 HeapRegion* new_region_try_secondary_free_list(); 489 490 // Try to allocate a single non-humongous HeapRegion sufficient for 491 // an allocation of the given word_size. If do_expand is true, 492 // attempt to expand the heap if necessary to satisfy the allocation 493 // request. 494 HeapRegion* new_region(size_t word_size, bool do_expand); 495 496 // Attempt to satisfy a humongous allocation request of the given 497 // size by finding a contiguous set of free regions of num_regions 498 // length and remove them from the master free list. Return the 499 // index of the first region or G1_NULL_HRS_INDEX if the search 500 // was unsuccessful. 501 uint humongous_obj_allocate_find_first(uint num_regions, 502 size_t word_size); 503 504 // Initialize a contiguous set of free regions of length num_regions 505 // and starting at index first so that they appear as a single 506 // humongous region. 507 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 508 uint num_regions, 509 size_t word_size); 510 511 // Attempt to allocate a humongous object of the given size. Return 512 // NULL if unsuccessful. 513 HeapWord* humongous_obj_allocate(size_t word_size); 514 515 // The following two methods, allocate_new_tlab() and 516 // mem_allocate(), are the two main entry points from the runtime 517 // into the G1's allocation routines. They have the following 518 // assumptions: 519 // 520 // * They should both be called outside safepoints. 521 // 522 // * They should both be called without holding the Heap_lock. 523 // 524 // * All allocation requests for new TLABs should go to 525 // allocate_new_tlab(). 526 // 527 // * All non-TLAB allocation requests should go to mem_allocate(). 528 // 529 // * If either call cannot satisfy the allocation request using the 530 // current allocating region, they will try to get a new one. If 531 // this fails, they will attempt to do an evacuation pause and 532 // retry the allocation. 533 // 534 // * If all allocation attempts fail, even after trying to schedule 535 // an evacuation pause, allocate_new_tlab() will return NULL, 536 // whereas mem_allocate() will attempt a heap expansion and/or 537 // schedule a Full GC. 538 // 539 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 540 // should never be called with word_size being humongous. All 541 // humongous allocation requests should go to mem_allocate() which 542 // will satisfy them with a special path. 543 544 virtual HeapWord* allocate_new_tlab(size_t word_size); 545 546 virtual HeapWord* mem_allocate(size_t word_size, 547 bool* gc_overhead_limit_was_exceeded); 548 549 // The following three methods take a gc_count_before_ret 550 // parameter which is used to return the GC count if the method 551 // returns NULL. Given that we are required to read the GC count 552 // while holding the Heap_lock, and these paths will take the 553 // Heap_lock at some point, it's easier to get them to read the GC 554 // count while holding the Heap_lock before they return NULL instead 555 // of the caller (namely: mem_allocate()) having to also take the 556 // Heap_lock just to read the GC count. 557 558 // First-level mutator allocation attempt: try to allocate out of 559 // the mutator alloc region without taking the Heap_lock. This 560 // should only be used for non-humongous allocations. 561 inline HeapWord* attempt_allocation(size_t word_size, 562 unsigned int* gc_count_before_ret, 563 int* gclocker_retry_count_ret); 564 565 // Second-level mutator allocation attempt: take the Heap_lock and 566 // retry the allocation attempt, potentially scheduling a GC 567 // pause. This should only be used for non-humongous allocations. 568 HeapWord* attempt_allocation_slow(size_t word_size, 569 unsigned int* gc_count_before_ret, 570 int* gclocker_retry_count_ret); 571 572 // Takes the Heap_lock and attempts a humongous allocation. It can 573 // potentially schedule a GC pause. 574 HeapWord* attempt_allocation_humongous(size_t word_size, 575 unsigned int* gc_count_before_ret, 576 int* gclocker_retry_count_ret); 577 578 // Allocation attempt that should be called during safepoints (e.g., 579 // at the end of a successful GC). expect_null_mutator_alloc_region 580 // specifies whether the mutator alloc region is expected to be NULL 581 // or not. 582 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 583 bool expect_null_mutator_alloc_region); 584 585 // It dirties the cards that cover the block so that so that the post 586 // write barrier never queues anything when updating objects on this 587 // block. It is assumed (and in fact we assert) that the block 588 // belongs to a young region. 589 inline void dirty_young_block(HeapWord* start, size_t word_size); 590 591 // Allocate blocks during garbage collection. Will ensure an 592 // allocation region, either by picking one or expanding the 593 // heap, and then allocate a block of the given size. The block 594 // may not be a humongous - it must fit into a single heap region. 595 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size); 596 597 HeapWord* allocate_during_gc_slow(GCAllocPurpose purpose, 598 HeapRegion* alloc_region, 599 bool par, 600 size_t word_size); 601 602 // Ensure that no further allocations can happen in "r", bearing in mind 603 // that parallel threads might be attempting allocations. 604 void par_allocate_remaining_space(HeapRegion* r); 605 606 // Allocation attempt during GC for a survivor object / PLAB. 607 inline HeapWord* survivor_attempt_allocation(size_t word_size); 608 609 // Allocation attempt during GC for an old object / PLAB. 610 inline HeapWord* old_attempt_allocation(size_t word_size); 611 612 // These methods are the "callbacks" from the G1AllocRegion class. 613 614 // For mutator alloc regions. 615 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 616 void retire_mutator_alloc_region(HeapRegion* alloc_region, 617 size_t allocated_bytes); 618 619 // For GC alloc regions. 620 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 621 GCAllocPurpose ap); 622 void retire_gc_alloc_region(HeapRegion* alloc_region, 623 size_t allocated_bytes, GCAllocPurpose ap); 624 625 // - if explicit_gc is true, the GC is for a System.gc() or a heap 626 // inspection request and should collect the entire heap 627 // - if clear_all_soft_refs is true, all soft references should be 628 // cleared during the GC 629 // - if explicit_gc is false, word_size describes the allocation that 630 // the GC should attempt (at least) to satisfy 631 // - it returns false if it is unable to do the collection due to the 632 // GC locker being active, true otherwise 633 bool do_collection(bool explicit_gc, 634 bool clear_all_soft_refs, 635 size_t word_size); 636 637 // Callback from VM_G1CollectFull operation. 638 // Perform a full collection. 639 virtual void do_full_collection(bool clear_all_soft_refs); 640 641 // Resize the heap if necessary after a full collection. If this is 642 // after a collect-for allocation, "word_size" is the allocation size, 643 // and will be considered part of the used portion of the heap. 644 void resize_if_necessary_after_full_collection(size_t word_size); 645 646 // Callback from VM_G1CollectForAllocation operation. 647 // This function does everything necessary/possible to satisfy a 648 // failed allocation request (including collection, expansion, etc.) 649 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded); 650 651 // Attempting to expand the heap sufficiently 652 // to support an allocation of the given "word_size". If 653 // successful, perform the allocation and return the address of the 654 // allocated block, or else "NULL". 655 HeapWord* expand_and_allocate(size_t word_size); 656 657 // Process any reference objects discovered during 658 // an incremental evacuation pause. 659 void process_discovered_references(uint no_of_gc_workers); 660 661 // Enqueue any remaining discovered references 662 // after processing. 663 void enqueue_discovered_references(uint no_of_gc_workers); 664 665 public: 666 667 G1MonitoringSupport* g1mm() { 668 assert(_g1mm != NULL, "should have been initialized"); 669 return _g1mm; 670 } 671 672 // Expand the garbage-first heap by at least the given size (in bytes!). 673 // Returns true if the heap was expanded by the requested amount; 674 // false otherwise. 675 // (Rounds up to a HeapRegion boundary.) 676 bool expand(size_t expand_bytes); 677 678 // Do anything common to GC's. 679 virtual void gc_prologue(bool full); 680 virtual void gc_epilogue(bool full); 681 682 // We register a region with the fast "in collection set" test. We 683 // simply set to true the array slot corresponding to this region. 684 void register_region_with_in_cset_fast_test(HeapRegion* r) { 685 assert(_in_cset_fast_test_base != NULL, "sanity"); 686 assert(r->in_collection_set(), "invariant"); 687 uint index = r->hrs_index(); 688 assert(index < _in_cset_fast_test_length, "invariant"); 689 assert(!_in_cset_fast_test_base[index], "invariant"); 690 _in_cset_fast_test_base[index] = true; 691 } 692 693 // This is a fast test on whether a reference points into the 694 // collection set or not. It does not assume that the reference 695 // points into the heap; if it doesn't, it will return false. 696 bool in_cset_fast_test(oop obj) { 697 assert(_in_cset_fast_test != NULL, "sanity"); 698 if (_g1_committed.contains((HeapWord*) obj)) { 699 // no need to subtract the bottom of the heap from obj, 700 // _in_cset_fast_test is biased 701 uintx index = (uintx) obj >> HeapRegion::LogOfHRGrainBytes; 702 bool ret = _in_cset_fast_test[index]; 703 // let's make sure the result is consistent with what the slower 704 // test returns 705 assert( ret || !obj_in_cs(obj), "sanity"); 706 assert(!ret || obj_in_cs(obj), "sanity"); 707 return ret; 708 } else { 709 return false; 710 } 711 } 712 713 void clear_cset_fast_test() { 714 assert(_in_cset_fast_test_base != NULL, "sanity"); 715 memset(_in_cset_fast_test_base, false, 716 (size_t) _in_cset_fast_test_length * sizeof(bool)); 717 } 718 719 // This is called at the start of either a concurrent cycle or a Full 720 // GC to update the number of old marking cycles started. 721 void increment_old_marking_cycles_started(); 722 723 // This is called at the end of either a concurrent cycle or a Full 724 // GC to update the number of old marking cycles completed. Those two 725 // can happen in a nested fashion, i.e., we start a concurrent 726 // cycle, a Full GC happens half-way through it which ends first, 727 // and then the cycle notices that a Full GC happened and ends 728 // too. The concurrent parameter is a boolean to help us do a bit 729 // tighter consistency checking in the method. If concurrent is 730 // false, the caller is the inner caller in the nesting (i.e., the 731 // Full GC). If concurrent is true, the caller is the outer caller 732 // in this nesting (i.e., the concurrent cycle). Further nesting is 733 // not currently supported. The end of this call also notifies 734 // the FullGCCount_lock in case a Java thread is waiting for a full 735 // GC to happen (e.g., it called System.gc() with 736 // +ExplicitGCInvokesConcurrent). 737 void increment_old_marking_cycles_completed(bool concurrent); 738 739 unsigned int old_marking_cycles_completed() { 740 return _old_marking_cycles_completed; 741 } 742 743 G1HRPrinter* hr_printer() { return &_hr_printer; } 744 745 protected: 746 747 // Shrink the garbage-first heap by at most the given size (in bytes!). 748 // (Rounds down to a HeapRegion boundary.) 749 virtual void shrink(size_t expand_bytes); 750 void shrink_helper(size_t expand_bytes); 751 752 #if TASKQUEUE_STATS 753 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 754 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 755 void reset_taskqueue_stats(); 756 #endif // TASKQUEUE_STATS 757 758 // Schedule the VM operation that will do an evacuation pause to 759 // satisfy an allocation request of word_size. *succeeded will 760 // return whether the VM operation was successful (it did do an 761 // evacuation pause) or not (another thread beat us to it or the GC 762 // locker was active). Given that we should not be holding the 763 // Heap_lock when we enter this method, we will pass the 764 // gc_count_before (i.e., total_collections()) as a parameter since 765 // it has to be read while holding the Heap_lock. Currently, both 766 // methods that call do_collection_pause() release the Heap_lock 767 // before the call, so it's easy to read gc_count_before just before. 768 HeapWord* do_collection_pause(size_t word_size, 769 unsigned int gc_count_before, 770 bool* succeeded); 771 772 // The guts of the incremental collection pause, executed by the vm 773 // thread. It returns false if it is unable to do the collection due 774 // to the GC locker being active, true otherwise 775 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 776 777 // Actually do the work of evacuating the collection set. 778 void evacuate_collection_set(); 779 780 // The g1 remembered set of the heap. 781 G1RemSet* _g1_rem_set; 782 // And it's mod ref barrier set, used to track updates for the above. 783 ModRefBarrierSet* _mr_bs; 784 785 // A set of cards that cover the objects for which the Rsets should be updated 786 // concurrently after the collection. 787 DirtyCardQueueSet _dirty_card_queue_set; 788 789 // The closure used to refine a single card. 790 RefineCardTableEntryClosure* _refine_cte_cl; 791 792 // A function to check the consistency of dirty card logs. 793 void check_ct_logs_at_safepoint(); 794 795 // A DirtyCardQueueSet that is used to hold cards that contain 796 // references into the current collection set. This is used to 797 // update the remembered sets of the regions in the collection 798 // set in the event of an evacuation failure. 799 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 800 801 // After a collection pause, make the regions in the CS into free 802 // regions. 803 void free_collection_set(HeapRegion* cs_head); 804 805 // Abandon the current collection set without recording policy 806 // statistics or updating free lists. 807 void abandon_collection_set(HeapRegion* cs_head); 808 809 // Applies "scan_non_heap_roots" to roots outside the heap, 810 // "scan_rs" to roots inside the heap (having done "set_region" to 811 // indicate the region in which the root resides), 812 // and does "scan_metadata" If "scan_rs" is 813 // NULL, then this step is skipped. The "worker_i" 814 // param is for use with parallel roots processing, and should be 815 // the "i" of the calling parallel worker thread's work(i) function. 816 // In the sequential case this param will be ignored. 817 void g1_process_strong_roots(bool is_scavenging, 818 ScanningOption so, 819 OopClosure* scan_non_heap_roots, 820 OopsInHeapRegionClosure* scan_rs, 821 G1KlassScanClosure* scan_klasses, 822 int worker_i); 823 824 // Apply "blk" to all the weak roots of the system. These include 825 // JNI weak roots, the code cache, system dictionary, symbol table, 826 // string table, and referents of reachable weak refs. 827 void g1_process_weak_roots(OopClosure* root_closure); 828 829 // Frees a non-humongous region by initializing its contents and 830 // adding it to the free list that's passed as a parameter (this is 831 // usually a local list which will be appended to the master free 832 // list later). The used bytes of freed regions are accumulated in 833 // pre_used. If par is true, the region's RSet will not be freed 834 // up. The assumption is that this will be done later. 835 void free_region(HeapRegion* hr, 836 size_t* pre_used, 837 FreeRegionList* free_list, 838 bool par); 839 840 // Frees a humongous region by collapsing it into individual regions 841 // and calling free_region() for each of them. The freed regions 842 // will be added to the free list that's passed as a parameter (this 843 // is usually a local list which will be appended to the master free 844 // list later). The used bytes of freed regions are accumulated in 845 // pre_used. If par is true, the region's RSet will not be freed 846 // up. The assumption is that this will be done later. 847 void free_humongous_region(HeapRegion* hr, 848 size_t* pre_used, 849 FreeRegionList* free_list, 850 HumongousRegionSet* humongous_proxy_set, 851 bool par); 852 853 // Notifies all the necessary spaces that the committed space has 854 // been updated (either expanded or shrunk). It should be called 855 // after _g1_storage is updated. 856 void update_committed_space(HeapWord* old_end, HeapWord* new_end); 857 858 // The concurrent marker (and the thread it runs in.) 859 ConcurrentMark* _cm; 860 ConcurrentMarkThread* _cmThread; 861 bool _mark_in_progress; 862 863 // The concurrent refiner. 864 ConcurrentG1Refine* _cg1r; 865 866 // The parallel task queues 867 RefToScanQueueSet *_task_queues; 868 869 // True iff a evacuation has failed in the current collection. 870 bool _evacuation_failed; 871 872 // Set the attribute indicating whether evacuation has failed in the 873 // current collection. 874 void set_evacuation_failed(bool b) { _evacuation_failed = b; } 875 876 // Failed evacuations cause some logical from-space objects to have 877 // forwarding pointers to themselves. Reset them. 878 void remove_self_forwarding_pointers(); 879 880 // Together, these store an object with a preserved mark, and its mark value. 881 Stack<oop, mtGC> _objs_with_preserved_marks; 882 Stack<markOop, mtGC> _preserved_marks_of_objs; 883 884 // Preserve the mark of "obj", if necessary, in preparation for its mark 885 // word being overwritten with a self-forwarding-pointer. 886 void preserve_mark_if_necessary(oop obj, markOop m); 887 888 // The stack of evac-failure objects left to be scanned. 889 GrowableArray<oop>* _evac_failure_scan_stack; 890 // The closure to apply to evac-failure objects. 891 892 OopsInHeapRegionClosure* _evac_failure_closure; 893 // Set the field above. 894 void 895 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) { 896 _evac_failure_closure = evac_failure_closure; 897 } 898 899 // Push "obj" on the scan stack. 900 void push_on_evac_failure_scan_stack(oop obj); 901 // Process scan stack entries until the stack is empty. 902 void drain_evac_failure_scan_stack(); 903 // True iff an invocation of "drain_scan_stack" is in progress; to 904 // prevent unnecessary recursion. 905 bool _drain_in_progress; 906 907 // Do any necessary initialization for evacuation-failure handling. 908 // "cl" is the closure that will be used to process evac-failure 909 // objects. 910 void init_for_evac_failure(OopsInHeapRegionClosure* cl); 911 // Do any necessary cleanup for evacuation-failure handling data 912 // structures. 913 void finalize_for_evac_failure(); 914 915 // An attempt to evacuate "obj" has failed; take necessary steps. 916 oop handle_evacuation_failure_par(OopsInHeapRegionClosure* cl, oop obj); 917 void handle_evacuation_failure_common(oop obj, markOop m); 918 919 #ifndef PRODUCT 920 // Support for forcing evacuation failures. Analogous to 921 // PromotionFailureALot for the other collectors. 922 923 // Records whether G1EvacuationFailureALot should be in effect 924 // for the current GC 925 bool _evacuation_failure_alot_for_current_gc; 926 927 // Used to record the GC number for interval checking when 928 // determining whether G1EvaucationFailureALot is in effect 929 // for the current GC. 930 size_t _evacuation_failure_alot_gc_number; 931 932 // Count of the number of evacuations between failures. 933 volatile size_t _evacuation_failure_alot_count; 934 935 // Set whether G1EvacuationFailureALot should be in effect 936 // for the current GC (based upon the type of GC and which 937 // command line flags are set); 938 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 939 bool during_initial_mark, 940 bool during_marking); 941 942 inline void set_evacuation_failure_alot_for_current_gc(); 943 944 // Return true if it's time to cause an evacuation failure. 945 inline bool evacuation_should_fail(); 946 947 // Reset the G1EvacuationFailureALot counters. Should be called at 948 // the end of an evacuation pause in which an evacuation failure ocurred. 949 inline void reset_evacuation_should_fail(); 950 #endif // !PRODUCT 951 952 // ("Weak") Reference processing support. 953 // 954 // G1 has 2 instances of the referece processor class. One 955 // (_ref_processor_cm) handles reference object discovery 956 // and subsequent processing during concurrent marking cycles. 957 // 958 // The other (_ref_processor_stw) handles reference object 959 // discovery and processing during full GCs and incremental 960 // evacuation pauses. 961 // 962 // During an incremental pause, reference discovery will be 963 // temporarily disabled for _ref_processor_cm and will be 964 // enabled for _ref_processor_stw. At the end of the evacuation 965 // pause references discovered by _ref_processor_stw will be 966 // processed and discovery will be disabled. The previous 967 // setting for reference object discovery for _ref_processor_cm 968 // will be re-instated. 969 // 970 // At the start of marking: 971 // * Discovery by the CM ref processor is verified to be inactive 972 // and it's discovered lists are empty. 973 // * Discovery by the CM ref processor is then enabled. 974 // 975 // At the end of marking: 976 // * Any references on the CM ref processor's discovered 977 // lists are processed (possibly MT). 978 // 979 // At the start of full GC we: 980 // * Disable discovery by the CM ref processor and 981 // empty CM ref processor's discovered lists 982 // (without processing any entries). 983 // * Verify that the STW ref processor is inactive and it's 984 // discovered lists are empty. 985 // * Temporarily set STW ref processor discovery as single threaded. 986 // * Temporarily clear the STW ref processor's _is_alive_non_header 987 // field. 988 // * Finally enable discovery by the STW ref processor. 989 // 990 // The STW ref processor is used to record any discovered 991 // references during the full GC. 992 // 993 // At the end of a full GC we: 994 // * Enqueue any reference objects discovered by the STW ref processor 995 // that have non-live referents. This has the side-effect of 996 // making the STW ref processor inactive by disabling discovery. 997 // * Verify that the CM ref processor is still inactive 998 // and no references have been placed on it's discovered 999 // lists (also checked as a precondition during initial marking). 1000 1001 // The (stw) reference processor... 1002 ReferenceProcessor* _ref_processor_stw; 1003 1004 // During reference object discovery, the _is_alive_non_header 1005 // closure (if non-null) is applied to the referent object to 1006 // determine whether the referent is live. If so then the 1007 // reference object does not need to be 'discovered' and can 1008 // be treated as a regular oop. This has the benefit of reducing 1009 // the number of 'discovered' reference objects that need to 1010 // be processed. 1011 // 1012 // Instance of the is_alive closure for embedding into the 1013 // STW reference processor as the _is_alive_non_header field. 1014 // Supplying a value for the _is_alive_non_header field is 1015 // optional but doing so prevents unnecessary additions to 1016 // the discovered lists during reference discovery. 1017 G1STWIsAliveClosure _is_alive_closure_stw; 1018 1019 // The (concurrent marking) reference processor... 1020 ReferenceProcessor* _ref_processor_cm; 1021 1022 // Instance of the concurrent mark is_alive closure for embedding 1023 // into the Concurrent Marking reference processor as the 1024 // _is_alive_non_header field. Supplying a value for the 1025 // _is_alive_non_header field is optional but doing so prevents 1026 // unnecessary additions to the discovered lists during reference 1027 // discovery. 1028 G1CMIsAliveClosure _is_alive_closure_cm; 1029 1030 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 1031 HeapRegion** _worker_cset_start_region; 1032 1033 // Time stamp to validate the regions recorded in the cache 1034 // used by G1CollectedHeap::start_cset_region_for_worker(). 1035 // The heap region entry for a given worker is valid iff 1036 // the associated time stamp value matches the current value 1037 // of G1CollectedHeap::_gc_time_stamp. 1038 unsigned int* _worker_cset_start_region_time_stamp; 1039 1040 enum G1H_process_strong_roots_tasks { 1041 G1H_PS_filter_satb_buffers, 1042 G1H_PS_refProcessor_oops_do, 1043 // Leave this one last. 1044 G1H_PS_NumElements 1045 }; 1046 1047 SubTasksDone* _process_strong_tasks; 1048 1049 volatile bool _free_regions_coming; 1050 1051 public: 1052 1053 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; } 1054 1055 void set_refine_cte_cl_concurrency(bool concurrent); 1056 1057 RefToScanQueue *task_queue(int i) const; 1058 1059 // A set of cards where updates happened during the GC 1060 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 1061 1062 // A DirtyCardQueueSet that is used to hold cards that contain 1063 // references into the current collection set. This is used to 1064 // update the remembered sets of the regions in the collection 1065 // set in the event of an evacuation failure. 1066 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 1067 { return _into_cset_dirty_card_queue_set; } 1068 1069 // Create a G1CollectedHeap with the specified policy. 1070 // Must call the initialize method afterwards. 1071 // May not return if something goes wrong. 1072 G1CollectedHeap(G1CollectorPolicy* policy); 1073 1074 // Initialize the G1CollectedHeap to have the initial and 1075 // maximum sizes and remembered and barrier sets 1076 // specified by the policy object. 1077 jint initialize(); 1078 1079 // Initialize weak reference processing. 1080 virtual void ref_processing_init(); 1081 1082 void set_par_threads(uint t) { 1083 SharedHeap::set_par_threads(t); 1084 // Done in SharedHeap but oddly there are 1085 // two _process_strong_tasks's in a G1CollectedHeap 1086 // so do it here too. 1087 _process_strong_tasks->set_n_threads(t); 1088 } 1089 1090 // Set _n_par_threads according to a policy TBD. 1091 void set_par_threads(); 1092 1093 void set_n_termination(int t) { 1094 _process_strong_tasks->set_n_threads(t); 1095 } 1096 1097 virtual CollectedHeap::Name kind() const { 1098 return CollectedHeap::G1CollectedHeap; 1099 } 1100 1101 // The current policy object for the collector. 1102 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1103 1104 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } 1105 1106 // Adaptive size policy. No such thing for g1. 1107 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1108 1109 // The rem set and barrier set. 1110 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1111 ModRefBarrierSet* mr_bs() const { return _mr_bs; } 1112 1113 unsigned get_gc_time_stamp() { 1114 return _gc_time_stamp; 1115 } 1116 1117 void reset_gc_time_stamp() { 1118 _gc_time_stamp = 0; 1119 OrderAccess::fence(); 1120 // Clear the cached CSet starting regions and time stamps. 1121 // Their validity is dependent on the GC timestamp. 1122 clear_cset_start_regions(); 1123 } 1124 1125 void check_gc_time_stamps() PRODUCT_RETURN; 1126 1127 void increment_gc_time_stamp() { 1128 ++_gc_time_stamp; 1129 OrderAccess::fence(); 1130 } 1131 1132 // Reset the given region's GC timestamp. If it's starts humongous, 1133 // also reset the GC timestamp of its corresponding 1134 // continues humongous regions too. 1135 void reset_gc_time_stamps(HeapRegion* hr); 1136 1137 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1138 DirtyCardQueue* into_cset_dcq, 1139 bool concurrent, int worker_i); 1140 1141 // The shared block offset table array. 1142 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1143 1144 // Reference Processing accessors 1145 1146 // The STW reference processor.... 1147 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1148 1149 // The Concurent Marking reference processor... 1150 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1151 1152 virtual size_t capacity() const; 1153 virtual size_t used() const; 1154 // This should be called when we're not holding the heap lock. The 1155 // result might be a bit inaccurate. 1156 size_t used_unlocked() const; 1157 size_t recalculate_used() const; 1158 1159 // These virtual functions do the actual allocation. 1160 // Some heaps may offer a contiguous region for shared non-blocking 1161 // allocation, via inlined code (by exporting the address of the top and 1162 // end fields defining the extent of the contiguous allocation region.) 1163 // But G1CollectedHeap doesn't yet support this. 1164 1165 // Return an estimate of the maximum allocation that could be performed 1166 // without triggering any collection or expansion activity. In a 1167 // generational collector, for example, this is probably the largest 1168 // allocation that could be supported (without expansion) in the youngest 1169 // generation. It is "unsafe" because no locks are taken; the result 1170 // should be treated as an approximation, not a guarantee, for use in 1171 // heuristic resizing decisions. 1172 virtual size_t unsafe_max_alloc(); 1173 1174 virtual bool is_maximal_no_gc() const { 1175 return _g1_storage.uncommitted_size() == 0; 1176 } 1177 1178 // The total number of regions in the heap. 1179 uint n_regions() { return _hrs.length(); } 1180 1181 // The max number of regions in the heap. 1182 uint max_regions() { return _hrs.max_length(); } 1183 1184 // The number of regions that are completely free. 1185 uint free_regions() { return _free_list.length(); } 1186 1187 // The number of regions that are not completely free. 1188 uint used_regions() { return n_regions() - free_regions(); } 1189 1190 // The number of regions available for "regular" expansion. 1191 uint expansion_regions() { return _expansion_regions; } 1192 1193 // Factory method for HeapRegion instances. It will return NULL if 1194 // the allocation fails. 1195 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom); 1196 1197 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1198 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1199 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1200 void verify_dirty_young_regions() PRODUCT_RETURN; 1201 1202 // verify_region_sets() performs verification over the region 1203 // lists. It will be compiled in the product code to be used when 1204 // necessary (i.e., during heap verification). 1205 void verify_region_sets(); 1206 1207 // verify_region_sets_optional() is planted in the code for 1208 // list verification in non-product builds (and it can be enabled in 1209 // product builds by definning HEAP_REGION_SET_FORCE_VERIFY to be 1). 1210 #if HEAP_REGION_SET_FORCE_VERIFY 1211 void verify_region_sets_optional() { 1212 verify_region_sets(); 1213 } 1214 #else // HEAP_REGION_SET_FORCE_VERIFY 1215 void verify_region_sets_optional() { } 1216 #endif // HEAP_REGION_SET_FORCE_VERIFY 1217 1218 #ifdef ASSERT 1219 bool is_on_master_free_list(HeapRegion* hr) { 1220 return hr->containing_set() == &_free_list; 1221 } 1222 1223 bool is_in_humongous_set(HeapRegion* hr) { 1224 return hr->containing_set() == &_humongous_set; 1225 } 1226 #endif // ASSERT 1227 1228 // Wrapper for the region list operations that can be called from 1229 // methods outside this class. 1230 1231 void secondary_free_list_add_as_tail(FreeRegionList* list) { 1232 _secondary_free_list.add_as_tail(list); 1233 } 1234 1235 void append_secondary_free_list() { 1236 _free_list.add_as_head(&_secondary_free_list); 1237 } 1238 1239 void append_secondary_free_list_if_not_empty_with_lock() { 1240 // If the secondary free list looks empty there's no reason to 1241 // take the lock and then try to append it. 1242 if (!_secondary_free_list.is_empty()) { 1243 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1244 append_secondary_free_list(); 1245 } 1246 } 1247 1248 void old_set_remove(HeapRegion* hr) { 1249 _old_set.remove(hr); 1250 } 1251 1252 size_t non_young_capacity_bytes() { 1253 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1254 } 1255 1256 void set_free_regions_coming(); 1257 void reset_free_regions_coming(); 1258 bool free_regions_coming() { return _free_regions_coming; } 1259 void wait_while_free_regions_coming(); 1260 1261 // Determine whether the given region is one that we are using as an 1262 // old GC alloc region. 1263 bool is_old_gc_alloc_region(HeapRegion* hr) { 1264 return hr == _retained_old_gc_alloc_region; 1265 } 1266 1267 // Perform a collection of the heap; intended for use in implementing 1268 // "System.gc". This probably implies as full a collection as the 1269 // "CollectedHeap" supports. 1270 virtual void collect(GCCause::Cause cause); 1271 1272 // The same as above but assume that the caller holds the Heap_lock. 1273 void collect_locked(GCCause::Cause cause); 1274 1275 // True iff a evacuation has failed in the most-recent collection. 1276 bool evacuation_failed() { return _evacuation_failed; } 1277 1278 // It will free a region if it has allocated objects in it that are 1279 // all dead. It calls either free_region() or 1280 // free_humongous_region() depending on the type of the region that 1281 // is passed to it. 1282 void free_region_if_empty(HeapRegion* hr, 1283 size_t* pre_used, 1284 FreeRegionList* free_list, 1285 OldRegionSet* old_proxy_set, 1286 HumongousRegionSet* humongous_proxy_set, 1287 HRRSCleanupTask* hrrs_cleanup_task, 1288 bool par); 1289 1290 // It appends the free list to the master free list and updates the 1291 // master humongous list according to the contents of the proxy 1292 // list. It also adjusts the total used bytes according to pre_used 1293 // (if par is true, it will do so by taking the ParGCRareEvent_lock). 1294 void update_sets_after_freeing_regions(size_t pre_used, 1295 FreeRegionList* free_list, 1296 OldRegionSet* old_proxy_set, 1297 HumongousRegionSet* humongous_proxy_set, 1298 bool par); 1299 1300 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1301 virtual bool is_in(const void* p) const; 1302 1303 // Return "TRUE" iff the given object address is within the collection 1304 // set. 1305 inline bool obj_in_cs(oop obj); 1306 1307 // Return "TRUE" iff the given object address is in the reserved 1308 // region of g1. 1309 bool is_in_g1_reserved(const void* p) const { 1310 return _g1_reserved.contains(p); 1311 } 1312 1313 // Returns a MemRegion that corresponds to the space that has been 1314 // reserved for the heap 1315 MemRegion g1_reserved() { 1316 return _g1_reserved; 1317 } 1318 1319 // Returns a MemRegion that corresponds to the space that has been 1320 // committed in the heap 1321 MemRegion g1_committed() { 1322 return _g1_committed; 1323 } 1324 1325 virtual bool is_in_closed_subset(const void* p) const; 1326 1327 // This resets the card table to all zeros. It is used after 1328 // a collection pause which used the card table to claim cards. 1329 void cleanUpCardTable(); 1330 1331 // Iteration functions. 1332 1333 // Iterate over all the ref-containing fields of all objects, calling 1334 // "cl.do_oop" on each. 1335 virtual void oop_iterate(ExtendedOopClosure* cl); 1336 1337 // Same as above, restricted to a memory region. 1338 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl); 1339 1340 // Iterate over all objects, calling "cl.do_object" on each. 1341 virtual void object_iterate(ObjectClosure* cl); 1342 1343 virtual void safe_object_iterate(ObjectClosure* cl) { 1344 object_iterate(cl); 1345 } 1346 1347 // Iterate over all objects allocated since the last collection, calling 1348 // "cl.do_object" on each. The heap must have been initialized properly 1349 // to support this function, or else this call will fail. 1350 virtual void object_iterate_since_last_GC(ObjectClosure* cl); 1351 1352 // Iterate over all spaces in use in the heap, in ascending address order. 1353 virtual void space_iterate(SpaceClosure* cl); 1354 1355 // Iterate over heap regions, in address order, terminating the 1356 // iteration early if the "doHeapRegion" method returns "true". 1357 void heap_region_iterate(HeapRegionClosure* blk) const; 1358 1359 // Return the region with the given index. It assumes the index is valid. 1360 HeapRegion* region_at(uint index) const { return _hrs.at(index); } 1361 1362 // Divide the heap region sequence into "chunks" of some size (the number 1363 // of regions divided by the number of parallel threads times some 1364 // overpartition factor, currently 4). Assumes that this will be called 1365 // in parallel by ParallelGCThreads worker threads with discinct worker 1366 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel 1367 // calls will use the same "claim_value", and that that claim value is 1368 // different from the claim_value of any heap region before the start of 1369 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by 1370 // attempting to claim the first region in each chunk, and, if 1371 // successful, applying the closure to each region in the chunk (and 1372 // setting the claim value of the second and subsequent regions of the 1373 // chunk.) For now requires that "doHeapRegion" always returns "false", 1374 // i.e., that a closure never attempt to abort a traversal. 1375 void heap_region_par_iterate_chunked(HeapRegionClosure* blk, 1376 uint worker, 1377 uint no_of_par_workers, 1378 jint claim_value); 1379 1380 // It resets all the region claim values to the default. 1381 void reset_heap_region_claim_values(); 1382 1383 // Resets the claim values of regions in the current 1384 // collection set to the default. 1385 void reset_cset_heap_region_claim_values(); 1386 1387 #ifdef ASSERT 1388 bool check_heap_region_claim_values(jint claim_value); 1389 1390 // Same as the routine above but only checks regions in the 1391 // current collection set. 1392 bool check_cset_heap_region_claim_values(jint claim_value); 1393 #endif // ASSERT 1394 1395 // Clear the cached cset start regions and (more importantly) 1396 // the time stamps. Called when we reset the GC time stamp. 1397 void clear_cset_start_regions(); 1398 1399 // Given the id of a worker, obtain or calculate a suitable 1400 // starting region for iterating over the current collection set. 1401 HeapRegion* start_cset_region_for_worker(int worker_i); 1402 1403 // This is a convenience method that is used by the 1404 // HeapRegionIterator classes to calculate the starting region for 1405 // each worker so that they do not all start from the same region. 1406 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers); 1407 1408 // Iterate over the regions (if any) in the current collection set. 1409 void collection_set_iterate(HeapRegionClosure* blk); 1410 1411 // As above but starting from region r 1412 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1413 1414 // Returns the first (lowest address) compactible space in the heap. 1415 virtual CompactibleSpace* first_compactible_space(); 1416 1417 // A CollectedHeap will contain some number of spaces. This finds the 1418 // space containing a given address, or else returns NULL. 1419 virtual Space* space_containing(const void* addr) const; 1420 1421 // A G1CollectedHeap will contain some number of heap regions. This 1422 // finds the region containing a given address, or else returns NULL. 1423 template <class T> 1424 inline HeapRegion* heap_region_containing(const T addr) const; 1425 1426 // Like the above, but requires "addr" to be in the heap (to avoid a 1427 // null-check), and unlike the above, may return an continuing humongous 1428 // region. 1429 template <class T> 1430 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1431 1432 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1433 // each address in the (reserved) heap is a member of exactly 1434 // one block. The defining characteristic of a block is that it is 1435 // possible to find its size, and thus to progress forward to the next 1436 // block. (Blocks may be of different sizes.) Thus, blocks may 1437 // represent Java objects, or they might be free blocks in a 1438 // free-list-based heap (or subheap), as long as the two kinds are 1439 // distinguishable and the size of each is determinable. 1440 1441 // Returns the address of the start of the "block" that contains the 1442 // address "addr". We say "blocks" instead of "object" since some heaps 1443 // may not pack objects densely; a chunk may either be an object or a 1444 // non-object. 1445 virtual HeapWord* block_start(const void* addr) const; 1446 1447 // Requires "addr" to be the start of a chunk, and returns its size. 1448 // "addr + size" is required to be the start of a new chunk, or the end 1449 // of the active area of the heap. 1450 virtual size_t block_size(const HeapWord* addr) const; 1451 1452 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1453 // the block is an object. 1454 virtual bool block_is_obj(const HeapWord* addr) const; 1455 1456 // Does this heap support heap inspection? (+PrintClassHistogram) 1457 virtual bool supports_heap_inspection() const { return true; } 1458 1459 // Section on thread-local allocation buffers (TLABs) 1460 // See CollectedHeap for semantics. 1461 1462 virtual bool supports_tlab_allocation() const; 1463 virtual size_t tlab_capacity(Thread* thr) const; 1464 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const; 1465 1466 // Can a compiler initialize a new object without store barriers? 1467 // This permission only extends from the creation of a new object 1468 // via a TLAB up to the first subsequent safepoint. If such permission 1469 // is granted for this heap type, the compiler promises to call 1470 // defer_store_barrier() below on any slow path allocation of 1471 // a new object for which such initializing store barriers will 1472 // have been elided. G1, like CMS, allows this, but should be 1473 // ready to provide a compensating write barrier as necessary 1474 // if that storage came out of a non-young region. The efficiency 1475 // of this implementation depends crucially on being able to 1476 // answer very efficiently in constant time whether a piece of 1477 // storage in the heap comes from a young region or not. 1478 // See ReduceInitialCardMarks. 1479 virtual bool can_elide_tlab_store_barriers() const { 1480 return true; 1481 } 1482 1483 virtual bool card_mark_must_follow_store() const { 1484 return true; 1485 } 1486 1487 bool is_in_young(const oop obj) { 1488 HeapRegion* hr = heap_region_containing(obj); 1489 return hr != NULL && hr->is_young(); 1490 } 1491 1492 #ifdef ASSERT 1493 virtual bool is_in_partial_collection(const void* p); 1494 #endif 1495 1496 virtual bool is_scavengable(const void* addr); 1497 1498 // We don't need barriers for initializing stores to objects 1499 // in the young gen: for the SATB pre-barrier, there is no 1500 // pre-value that needs to be remembered; for the remembered-set 1501 // update logging post-barrier, we don't maintain remembered set 1502 // information for young gen objects. 1503 virtual bool can_elide_initializing_store_barrier(oop new_obj) { 1504 return is_in_young(new_obj); 1505 } 1506 1507 // Returns "true" iff the given word_size is "very large". 1508 static bool isHumongous(size_t word_size) { 1509 // Note this has to be strictly greater-than as the TLABs 1510 // are capped at the humongous thresold and we want to 1511 // ensure that we don't try to allocate a TLAB as 1512 // humongous and that we don't allocate a humongous 1513 // object in a TLAB. 1514 return word_size > _humongous_object_threshold_in_words; 1515 } 1516 1517 // Update mod union table with the set of dirty cards. 1518 void updateModUnion(); 1519 1520 // Set the mod union bits corresponding to the given memRegion. Note 1521 // that this is always a safe operation, since it doesn't clear any 1522 // bits. 1523 void markModUnionRange(MemRegion mr); 1524 1525 // Records the fact that a marking phase is no longer in progress. 1526 void set_marking_complete() { 1527 _mark_in_progress = false; 1528 } 1529 void set_marking_started() { 1530 _mark_in_progress = true; 1531 } 1532 bool mark_in_progress() { 1533 return _mark_in_progress; 1534 } 1535 1536 // Print the maximum heap capacity. 1537 virtual size_t max_capacity() const; 1538 1539 virtual jlong millis_since_last_gc(); 1540 1541 // Perform any cleanup actions necessary before allowing a verification. 1542 virtual void prepare_for_verify(); 1543 1544 // Perform verification. 1545 1546 // vo == UsePrevMarking -> use "prev" marking information, 1547 // vo == UseNextMarking -> use "next" marking information 1548 // vo == UseMarkWord -> use the mark word in the object header 1549 // 1550 // NOTE: Only the "prev" marking information is guaranteed to be 1551 // consistent most of the time, so most calls to this should use 1552 // vo == UsePrevMarking. 1553 // Currently, there is only one case where this is called with 1554 // vo == UseNextMarking, which is to verify the "next" marking 1555 // information at the end of remark. 1556 // Currently there is only one place where this is called with 1557 // vo == UseMarkWord, which is to verify the marking during a 1558 // full GC. 1559 void verify(bool silent, VerifyOption vo); 1560 1561 // Override; it uses the "prev" marking information 1562 virtual void verify(bool silent); 1563 virtual void print_on(outputStream* st) const; 1564 virtual void print_extended_on(outputStream* st) const; 1565 virtual void print_on_error(outputStream* st) const; 1566 1567 virtual void print_gc_threads_on(outputStream* st) const; 1568 virtual void gc_threads_do(ThreadClosure* tc) const; 1569 1570 // Override 1571 void print_tracing_info() const; 1572 1573 // The following two methods are helpful for debugging RSet issues. 1574 void print_cset_rsets() PRODUCT_RETURN; 1575 void print_all_rsets() PRODUCT_RETURN; 1576 1577 // Convenience function to be used in situations where the heap type can be 1578 // asserted to be this type. 1579 static G1CollectedHeap* heap(); 1580 1581 void set_region_short_lived_locked(HeapRegion* hr); 1582 // add appropriate methods for any other surv rate groups 1583 1584 YoungList* young_list() { return _young_list; } 1585 1586 // debugging 1587 bool check_young_list_well_formed() { 1588 return _young_list->check_list_well_formed(); 1589 } 1590 1591 bool check_young_list_empty(bool check_heap, 1592 bool check_sample = true); 1593 1594 // *** Stuff related to concurrent marking. It's not clear to me that so 1595 // many of these need to be public. 1596 1597 // The functions below are helper functions that a subclass of 1598 // "CollectedHeap" can use in the implementation of its virtual 1599 // functions. 1600 // This performs a concurrent marking of the live objects in a 1601 // bitmap off to the side. 1602 void doConcurrentMark(); 1603 1604 bool isMarkedPrev(oop obj) const; 1605 bool isMarkedNext(oop obj) const; 1606 1607 // Determine if an object is dead, given the object and also 1608 // the region to which the object belongs. An object is dead 1609 // iff a) it was not allocated since the last mark and b) it 1610 // is not marked. 1611 1612 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1613 return 1614 !hr->obj_allocated_since_prev_marking(obj) && 1615 !isMarkedPrev(obj); 1616 } 1617 1618 // This function returns true when an object has been 1619 // around since the previous marking and hasn't yet 1620 // been marked during this marking. 1621 1622 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1623 return 1624 !hr->obj_allocated_since_next_marking(obj) && 1625 !isMarkedNext(obj); 1626 } 1627 1628 // Determine if an object is dead, given only the object itself. 1629 // This will find the region to which the object belongs and 1630 // then call the region version of the same function. 1631 1632 // Added if it is NULL it isn't dead. 1633 1634 bool is_obj_dead(const oop obj) const { 1635 const HeapRegion* hr = heap_region_containing(obj); 1636 if (hr == NULL) { 1637 if (obj == NULL) return false; 1638 else return true; 1639 } 1640 else return is_obj_dead(obj, hr); 1641 } 1642 1643 bool is_obj_ill(const oop obj) const { 1644 const HeapRegion* hr = heap_region_containing(obj); 1645 if (hr == NULL) { 1646 if (obj == NULL) return false; 1647 else return true; 1648 } 1649 else return is_obj_ill(obj, hr); 1650 } 1651 1652 // The methods below are here for convenience and dispatch the 1653 // appropriate method depending on value of the given VerifyOption 1654 // parameter. The options for that parameter are: 1655 // 1656 // vo == UsePrevMarking -> use "prev" marking information, 1657 // vo == UseNextMarking -> use "next" marking information, 1658 // vo == UseMarkWord -> use mark word from object header 1659 1660 bool is_obj_dead_cond(const oop obj, 1661 const HeapRegion* hr, 1662 const VerifyOption vo) const { 1663 switch (vo) { 1664 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 1665 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 1666 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 1667 default: ShouldNotReachHere(); 1668 } 1669 return false; // keep some compilers happy 1670 } 1671 1672 bool is_obj_dead_cond(const oop obj, 1673 const VerifyOption vo) const { 1674 switch (vo) { 1675 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 1676 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 1677 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 1678 default: ShouldNotReachHere(); 1679 } 1680 return false; // keep some compilers happy 1681 } 1682 1683 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1684 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1685 bool is_marked(oop obj, VerifyOption vo); 1686 const char* top_at_mark_start_str(VerifyOption vo); 1687 1688 // The following is just to alert the verification code 1689 // that a full collection has occurred and that the 1690 // remembered sets are no longer up to date. 1691 bool _full_collection; 1692 void set_full_collection() { _full_collection = true;} 1693 void clear_full_collection() {_full_collection = false;} 1694 bool full_collection() {return _full_collection;} 1695 1696 ConcurrentMark* concurrent_mark() const { return _cm; } 1697 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1698 1699 // The dirty cards region list is used to record a subset of regions 1700 // whose cards need clearing. The list if populated during the 1701 // remembered set scanning and drained during the card table 1702 // cleanup. Although the methods are reentrant, population/draining 1703 // phases must not overlap. For synchronization purposes the last 1704 // element on the list points to itself. 1705 HeapRegion* _dirty_cards_region_list; 1706 void push_dirty_cards_region(HeapRegion* hr); 1707 HeapRegion* pop_dirty_cards_region(); 1708 1709 public: 1710 void stop_conc_gc_threads(); 1711 1712 size_t pending_card_num(); 1713 size_t cards_scanned(); 1714 1715 protected: 1716 size_t _max_heap_capacity; 1717 }; 1718 1719 class G1ParGCAllocBuffer: public ParGCAllocBuffer { 1720 private: 1721 bool _retired; 1722 1723 public: 1724 G1ParGCAllocBuffer(size_t gclab_word_size); 1725 1726 void set_buf(HeapWord* buf) { 1727 ParGCAllocBuffer::set_buf(buf); 1728 _retired = false; 1729 } 1730 1731 void retire(bool end_of_gc, bool retain) { 1732 if (_retired) 1733 return; 1734 ParGCAllocBuffer::retire(end_of_gc, retain); 1735 _retired = true; 1736 } 1737 }; 1738 1739 class G1ParScanThreadState : public StackObj { 1740 protected: 1741 G1CollectedHeap* _g1h; 1742 RefToScanQueue* _refs; 1743 DirtyCardQueue _dcq; 1744 CardTableModRefBS* _ct_bs; 1745 G1RemSet* _g1_rem; 1746 1747 G1ParGCAllocBuffer _surviving_alloc_buffer; 1748 G1ParGCAllocBuffer _tenured_alloc_buffer; 1749 G1ParGCAllocBuffer* _alloc_buffers[GCAllocPurposeCount]; 1750 ageTable _age_table; 1751 1752 size_t _alloc_buffer_waste; 1753 size_t _undo_waste; 1754 1755 OopsInHeapRegionClosure* _evac_failure_cl; 1756 G1ParScanHeapEvacClosure* _evac_cl; 1757 G1ParScanPartialArrayClosure* _partial_scan_cl; 1758 1759 int _hash_seed; 1760 uint _queue_num; 1761 1762 size_t _term_attempts; 1763 1764 double _start; 1765 double _start_strong_roots; 1766 double _strong_roots_time; 1767 double _start_term; 1768 double _term_time; 1769 1770 // Map from young-age-index (0 == not young, 1 is youngest) to 1771 // surviving words. base is what we get back from the malloc call 1772 size_t* _surviving_young_words_base; 1773 // this points into the array, as we use the first few entries for padding 1774 size_t* _surviving_young_words; 1775 1776 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t)) 1777 1778 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; } 1779 1780 void add_to_undo_waste(size_t waste) { _undo_waste += waste; } 1781 1782 DirtyCardQueue& dirty_card_queue() { return _dcq; } 1783 CardTableModRefBS* ctbs() { return _ct_bs; } 1784 1785 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) { 1786 if (!from->is_survivor()) { 1787 _g1_rem->par_write_ref(from, p, tid); 1788 } 1789 } 1790 1791 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) { 1792 // If the new value of the field points to the same region or 1793 // is the to-space, we don't need to include it in the Rset updates. 1794 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) { 1795 size_t card_index = ctbs()->index_for(p); 1796 // If the card hasn't been added to the buffer, do it. 1797 if (ctbs()->mark_card_deferred(card_index)) { 1798 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index)); 1799 } 1800 } 1801 } 1802 1803 public: 1804 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num); 1805 1806 ~G1ParScanThreadState() { 1807 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC); 1808 } 1809 1810 RefToScanQueue* refs() { return _refs; } 1811 ageTable* age_table() { return &_age_table; } 1812 1813 G1ParGCAllocBuffer* alloc_buffer(GCAllocPurpose purpose) { 1814 return _alloc_buffers[purpose]; 1815 } 1816 1817 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; } 1818 size_t undo_waste() const { return _undo_waste; } 1819 1820 #ifdef ASSERT 1821 bool verify_ref(narrowOop* ref) const; 1822 bool verify_ref(oop* ref) const; 1823 bool verify_task(StarTask ref) const; 1824 #endif // ASSERT 1825 1826 template <class T> void push_on_queue(T* ref) { 1827 assert(verify_ref(ref), "sanity"); 1828 refs()->push(ref); 1829 } 1830 1831 template <class T> void update_rs(HeapRegion* from, T* p, int tid) { 1832 if (G1DeferredRSUpdate) { 1833 deferred_rs_update(from, p, tid); 1834 } else { 1835 immediate_rs_update(from, p, tid); 1836 } 1837 } 1838 1839 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) { 1840 HeapWord* obj = NULL; 1841 size_t gclab_word_size = _g1h->desired_plab_sz(purpose); 1842 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) { 1843 G1ParGCAllocBuffer* alloc_buf = alloc_buffer(purpose); 1844 add_to_alloc_buffer_waste(alloc_buf->words_remaining()); 1845 alloc_buf->retire(false /* end_of_gc */, false /* retain */); 1846 1847 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size); 1848 if (buf == NULL) return NULL; // Let caller handle allocation failure. 1849 // Otherwise. 1850 alloc_buf->set_word_size(gclab_word_size); 1851 alloc_buf->set_buf(buf); 1852 1853 obj = alloc_buf->allocate(word_sz); 1854 assert(obj != NULL, "buffer was definitely big enough..."); 1855 } else { 1856 obj = _g1h->par_allocate_during_gc(purpose, word_sz); 1857 } 1858 return obj; 1859 } 1860 1861 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) { 1862 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz); 1863 if (obj != NULL) return obj; 1864 return allocate_slow(purpose, word_sz); 1865 } 1866 1867 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) { 1868 if (alloc_buffer(purpose)->contains(obj)) { 1869 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1), 1870 "should contain whole object"); 1871 alloc_buffer(purpose)->undo_allocation(obj, word_sz); 1872 } else { 1873 CollectedHeap::fill_with_object(obj, word_sz); 1874 add_to_undo_waste(word_sz); 1875 } 1876 } 1877 1878 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) { 1879 _evac_failure_cl = evac_failure_cl; 1880 } 1881 OopsInHeapRegionClosure* evac_failure_closure() { 1882 return _evac_failure_cl; 1883 } 1884 1885 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) { 1886 _evac_cl = evac_cl; 1887 } 1888 1889 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) { 1890 _partial_scan_cl = partial_scan_cl; 1891 } 1892 1893 int* hash_seed() { return &_hash_seed; } 1894 uint queue_num() { return _queue_num; } 1895 1896 size_t term_attempts() const { return _term_attempts; } 1897 void note_term_attempt() { _term_attempts++; } 1898 1899 void start_strong_roots() { 1900 _start_strong_roots = os::elapsedTime(); 1901 } 1902 void end_strong_roots() { 1903 _strong_roots_time += (os::elapsedTime() - _start_strong_roots); 1904 } 1905 double strong_roots_time() const { return _strong_roots_time; } 1906 1907 void start_term_time() { 1908 note_term_attempt(); 1909 _start_term = os::elapsedTime(); 1910 } 1911 void end_term_time() { 1912 _term_time += (os::elapsedTime() - _start_term); 1913 } 1914 double term_time() const { return _term_time; } 1915 1916 double elapsed_time() const { 1917 return os::elapsedTime() - _start; 1918 } 1919 1920 static void 1921 print_termination_stats_hdr(outputStream* const st = gclog_or_tty); 1922 void 1923 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const; 1924 1925 size_t* surviving_young_words() { 1926 // We add on to hide entry 0 which accumulates surviving words for 1927 // age -1 regions (i.e. non-young ones) 1928 return _surviving_young_words; 1929 } 1930 1931 void retire_alloc_buffers() { 1932 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) { 1933 size_t waste = _alloc_buffers[ap]->words_remaining(); 1934 add_to_alloc_buffer_waste(waste); 1935 _alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap), 1936 true /* end_of_gc */, 1937 false /* retain */); 1938 } 1939 } 1940 1941 template <class T> void deal_with_reference(T* ref_to_scan) { 1942 if (has_partial_array_mask(ref_to_scan)) { 1943 _partial_scan_cl->do_oop_nv(ref_to_scan); 1944 } else { 1945 // Note: we can use "raw" versions of "region_containing" because 1946 // "obj_to_scan" is definitely in the heap, and is not in a 1947 // humongous region. 1948 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan); 1949 _evac_cl->set_region(r); 1950 _evac_cl->do_oop_nv(ref_to_scan); 1951 } 1952 } 1953 1954 void deal_with_reference(StarTask ref) { 1955 assert(verify_task(ref), "sanity"); 1956 if (ref.is_narrow()) { 1957 deal_with_reference((narrowOop*)ref); 1958 } else { 1959 deal_with_reference((oop*)ref); 1960 } 1961 } 1962 1963 public: 1964 void trim_queue(); 1965 }; 1966 1967 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP