1 /* 2 * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP 26 #define SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP 27 28 #include "gc_implementation/g1/concurrentMark.hpp" 29 #include "gc_implementation/g1/evacuationInfo.hpp" 30 #include "gc_implementation/g1/g1AllocRegion.hpp" 31 #include "gc_implementation/g1/g1HRPrinter.hpp" 32 #include "gc_implementation/g1/g1MonitoringSupport.hpp" 33 #include "gc_implementation/g1/g1RemSet.hpp" 34 #include "gc_implementation/g1/g1YCTypes.hpp" 35 #include "gc_implementation/g1/heapRegionSeq.hpp" 36 #include "gc_implementation/g1/heapRegionSets.hpp" 37 #include "gc_implementation/shared/hSpaceCounters.hpp" 38 #include "gc_implementation/shared/parGCAllocBuffer.hpp" 39 #include "memory/barrierSet.hpp" 40 #include "memory/memRegion.hpp" 41 #include "memory/sharedHeap.hpp" 42 #include "utilities/stack.hpp" 43 44 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 45 // It uses the "Garbage First" heap organization and algorithm, which 46 // may combine concurrent marking with parallel, incremental compaction of 47 // heap subsets that will yield large amounts of garbage. 48 49 // Forward declarations 50 class HeapRegion; 51 class HRRSCleanupTask; 52 class GenerationSpec; 53 class OopsInHeapRegionClosure; 54 class G1KlassScanClosure; 55 class G1ScanHeapEvacClosure; 56 class ObjectClosure; 57 class SpaceClosure; 58 class CompactibleSpaceClosure; 59 class Space; 60 class G1CollectorPolicy; 61 class GenRemSet; 62 class G1RemSet; 63 class HeapRegionRemSetIterator; 64 class ConcurrentMark; 65 class ConcurrentMarkThread; 66 class ConcurrentG1Refine; 67 class ConcurrentGCTimer; 68 class GenerationCounters; 69 class STWGCTimer; 70 class G1NewTracer; 71 class G1OldTracer; 72 class EvacuationFailedInfo; 73 class nmethod; 74 75 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 76 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 77 78 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 79 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 80 81 enum GCAllocPurpose { 82 GCAllocForTenured, 83 GCAllocForSurvived, 84 GCAllocPurposeCount 85 }; 86 87 class YoungList : public CHeapObj<mtGC> { 88 private: 89 G1CollectedHeap* _g1h; 90 91 HeapRegion* _head; 92 93 HeapRegion* _survivor_head; 94 HeapRegion* _survivor_tail; 95 96 HeapRegion* _curr; 97 98 uint _length; 99 uint _survivor_length; 100 101 size_t _last_sampled_rs_lengths; 102 size_t _sampled_rs_lengths; 103 104 void empty_list(HeapRegion* list); 105 106 public: 107 YoungList(G1CollectedHeap* g1h); 108 109 void push_region(HeapRegion* hr); 110 void add_survivor_region(HeapRegion* hr); 111 112 void empty_list(); 113 bool is_empty() { return _length == 0; } 114 uint length() { return _length; } 115 uint survivor_length() { return _survivor_length; } 116 117 // Currently we do not keep track of the used byte sum for the 118 // young list and the survivors and it'd be quite a lot of work to 119 // do so. When we'll eventually replace the young list with 120 // instances of HeapRegionLinkedList we'll get that for free. So, 121 // we'll report the more accurate information then. 122 size_t eden_used_bytes() { 123 assert(length() >= survivor_length(), "invariant"); 124 return (size_t) (length() - survivor_length()) * HeapRegion::GrainBytes; 125 } 126 size_t survivor_used_bytes() { 127 return (size_t) survivor_length() * HeapRegion::GrainBytes; 128 } 129 130 void rs_length_sampling_init(); 131 bool rs_length_sampling_more(); 132 void rs_length_sampling_next(); 133 134 void reset_sampled_info() { 135 _last_sampled_rs_lengths = 0; 136 } 137 size_t sampled_rs_lengths() { return _last_sampled_rs_lengths; } 138 139 // for development purposes 140 void reset_auxilary_lists(); 141 void clear() { _head = NULL; _length = 0; } 142 143 void clear_survivors() { 144 _survivor_head = NULL; 145 _survivor_tail = NULL; 146 _survivor_length = 0; 147 } 148 149 HeapRegion* first_region() { return _head; } 150 HeapRegion* first_survivor_region() { return _survivor_head; } 151 HeapRegion* last_survivor_region() { return _survivor_tail; } 152 153 // debugging 154 bool check_list_well_formed(); 155 bool check_list_empty(bool check_sample = true); 156 void print(); 157 }; 158 159 class MutatorAllocRegion : public G1AllocRegion { 160 protected: 161 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 162 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 163 public: 164 MutatorAllocRegion() 165 : G1AllocRegion("Mutator Alloc Region", false /* bot_updates */) { } 166 }; 167 168 class SurvivorGCAllocRegion : public G1AllocRegion { 169 protected: 170 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 171 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 172 public: 173 SurvivorGCAllocRegion() 174 : G1AllocRegion("Survivor GC Alloc Region", false /* bot_updates */) { } 175 }; 176 177 class OldGCAllocRegion : public G1AllocRegion { 178 protected: 179 virtual HeapRegion* allocate_new_region(size_t word_size, bool force); 180 virtual void retire_region(HeapRegion* alloc_region, size_t allocated_bytes); 181 public: 182 OldGCAllocRegion() 183 : G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { } 184 }; 185 186 // The G1 STW is alive closure. 187 // An instance is embedded into the G1CH and used as the 188 // (optional) _is_alive_non_header closure in the STW 189 // reference processor. It is also extensively used during 190 // reference processing during STW evacuation pauses. 191 class G1STWIsAliveClosure: public BoolObjectClosure { 192 G1CollectedHeap* _g1; 193 public: 194 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 195 bool do_object_b(oop p); 196 }; 197 198 class RefineCardTableEntryClosure; 199 200 class G1CollectedHeap : public SharedHeap { 201 friend class VM_G1CollectForAllocation; 202 friend class VM_G1CollectFull; 203 friend class VM_G1IncCollectionPause; 204 friend class VMStructs; 205 friend class MutatorAllocRegion; 206 friend class SurvivorGCAllocRegion; 207 friend class OldGCAllocRegion; 208 209 // Closures used in implementation. 210 template <bool do_gen_barrier, G1Barrier barrier, bool do_mark_object> 211 friend class G1ParCopyClosure; 212 friend class G1IsAliveClosure; 213 friend class G1EvacuateFollowersClosure; 214 friend class G1ParScanThreadState; 215 friend class G1ParScanClosureSuper; 216 friend class G1ParEvacuateFollowersClosure; 217 friend class G1ParTask; 218 friend class G1FreeGarbageRegionClosure; 219 friend class RefineCardTableEntryClosure; 220 friend class G1PrepareCompactClosure; 221 friend class RegionSorter; 222 friend class RegionResetter; 223 friend class CountRCClosure; 224 friend class EvacPopObjClosure; 225 friend class G1ParCleanupCTTask; 226 227 // Other related classes. 228 friend class G1MarkSweep; 229 230 private: 231 // The one and only G1CollectedHeap, so static functions can find it. 232 static G1CollectedHeap* _g1h; 233 234 static size_t _humongous_object_threshold_in_words; 235 236 // Storage for the G1 heap. 237 VirtualSpace _g1_storage; 238 MemRegion _g1_reserved; 239 240 // The part of _g1_storage that is currently committed. 241 MemRegion _g1_committed; 242 243 // The master free list. It will satisfy all new region allocations. 244 MasterFreeRegionList _free_list; 245 246 // The secondary free list which contains regions that have been 247 // freed up during the cleanup process. This will be appended to the 248 // master free list when appropriate. 249 SecondaryFreeRegionList _secondary_free_list; 250 251 // It keeps track of the old regions. 252 MasterOldRegionSet _old_set; 253 254 // It keeps track of the humongous regions. 255 MasterHumongousRegionSet _humongous_set; 256 257 // The number of regions we could create by expansion. 258 uint _expansion_regions; 259 260 // The block offset table for the G1 heap. 261 G1BlockOffsetSharedArray* _bot_shared; 262 263 // Tears down the region sets / lists so that they are empty and the 264 // regions on the heap do not belong to a region set / list. The 265 // only exception is the humongous set which we leave unaltered. If 266 // free_list_only is true, it will only tear down the master free 267 // list. It is called before a Full GC (free_list_only == false) or 268 // before heap shrinking (free_list_only == true). 269 void tear_down_region_sets(bool free_list_only); 270 271 // Rebuilds the region sets / lists so that they are repopulated to 272 // reflect the contents of the heap. The only exception is the 273 // humongous set which was not torn down in the first place. If 274 // free_list_only is true, it will only rebuild the master free 275 // list. It is called after a Full GC (free_list_only == false) or 276 // after heap shrinking (free_list_only == true). 277 void rebuild_region_sets(bool free_list_only); 278 279 // The sequence of all heap regions in the heap. 280 HeapRegionSeq _hrs; 281 282 // Alloc region used to satisfy mutator allocation requests. 283 MutatorAllocRegion _mutator_alloc_region; 284 285 // Alloc region used to satisfy allocation requests by the GC for 286 // survivor objects. 287 SurvivorGCAllocRegion _survivor_gc_alloc_region; 288 289 // PLAB sizing policy for survivors. 290 PLABStats _survivor_plab_stats; 291 292 // Alloc region used to satisfy allocation requests by the GC for 293 // old objects. 294 OldGCAllocRegion _old_gc_alloc_region; 295 296 // PLAB sizing policy for tenured objects. 297 PLABStats _old_plab_stats; 298 299 PLABStats* stats_for_purpose(GCAllocPurpose purpose) { 300 PLABStats* stats = NULL; 301 302 switch (purpose) { 303 case GCAllocForSurvived: 304 stats = &_survivor_plab_stats; 305 break; 306 case GCAllocForTenured: 307 stats = &_old_plab_stats; 308 break; 309 default: 310 assert(false, "unrecognized GCAllocPurpose"); 311 } 312 313 return stats; 314 } 315 316 // The last old region we allocated to during the last GC. 317 // Typically, it is not full so we should re-use it during the next GC. 318 HeapRegion* _retained_old_gc_alloc_region; 319 320 // It specifies whether we should attempt to expand the heap after a 321 // region allocation failure. If heap expansion fails we set this to 322 // false so that we don't re-attempt the heap expansion (it's likely 323 // that subsequent expansion attempts will also fail if one fails). 324 // Currently, it is only consulted during GC and it's reset at the 325 // start of each GC. 326 bool _expand_heap_after_alloc_failure; 327 328 // It resets the mutator alloc region before new allocations can take place. 329 void init_mutator_alloc_region(); 330 331 // It releases the mutator alloc region. 332 void release_mutator_alloc_region(); 333 334 // It initializes the GC alloc regions at the start of a GC. 335 void init_gc_alloc_regions(EvacuationInfo& evacuation_info); 336 337 // It releases the GC alloc regions at the end of a GC. 338 void release_gc_alloc_regions(uint no_of_gc_workers, EvacuationInfo& evacuation_info); 339 340 // It does any cleanup that needs to be done on the GC alloc regions 341 // before a Full GC. 342 void abandon_gc_alloc_regions(); 343 344 // Helper for monitoring and management support. 345 G1MonitoringSupport* _g1mm; 346 347 // Determines PLAB size for a particular allocation purpose. 348 size_t desired_plab_sz(GCAllocPurpose purpose); 349 350 // Outside of GC pauses, the number of bytes used in all regions other 351 // than the current allocation region. 352 size_t _summary_bytes_used; 353 354 // This is used for a quick test on whether a reference points into 355 // the collection set or not. Basically, we have an array, with one 356 // byte per region, and that byte denotes whether the corresponding 357 // region is in the collection set or not. The entry corresponding 358 // the bottom of the heap, i.e., region 0, is pointed to by 359 // _in_cset_fast_test_base. The _in_cset_fast_test field has been 360 // biased so that it actually points to address 0 of the address 361 // space, to make the test as fast as possible (we can simply shift 362 // the address to address into it, instead of having to subtract the 363 // bottom of the heap from the address before shifting it; basically 364 // it works in the same way the card table works). 365 bool* _in_cset_fast_test; 366 367 // The allocated array used for the fast test on whether a reference 368 // points into the collection set or not. This field is also used to 369 // free the array. 370 bool* _in_cset_fast_test_base; 371 372 // The length of the _in_cset_fast_test_base array. 373 uint _in_cset_fast_test_length; 374 375 volatile unsigned _gc_time_stamp; 376 377 size_t* _surviving_young_words; 378 379 G1HRPrinter _hr_printer; 380 381 void setup_surviving_young_words(); 382 void update_surviving_young_words(size_t* surv_young_words); 383 void cleanup_surviving_young_words(); 384 385 // It decides whether an explicit GC should start a concurrent cycle 386 // instead of doing a STW GC. Currently, a concurrent cycle is 387 // explicitly started if: 388 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 389 // (b) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 390 // (c) cause == _g1_humongous_allocation 391 bool should_do_concurrent_full_gc(GCCause::Cause cause); 392 393 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 394 // concurrent cycles) we have started. 395 volatile unsigned int _old_marking_cycles_started; 396 397 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 398 // concurrent cycles) we have completed. 399 volatile unsigned int _old_marking_cycles_completed; 400 401 bool _concurrent_cycle_started; 402 403 // This is a non-product method that is helpful for testing. It is 404 // called at the end of a GC and artificially expands the heap by 405 // allocating a number of dead regions. This way we can induce very 406 // frequent marking cycles and stress the cleanup / concurrent 407 // cleanup code more (as all the regions that will be allocated by 408 // this method will be found dead by the marking cycle). 409 void allocate_dummy_regions() PRODUCT_RETURN; 410 411 // Clear RSets after a compaction. It also resets the GC time stamps. 412 void clear_rsets_post_compaction(); 413 414 // If the HR printer is active, dump the state of the regions in the 415 // heap after a compaction. 416 void print_hrs_post_compaction(); 417 418 double verify(bool guard, const char* msg); 419 void verify_before_gc(); 420 void verify_after_gc(); 421 422 void log_gc_header(); 423 void log_gc_footer(double pause_time_sec); 424 425 // These are macros so that, if the assert fires, we get the correct 426 // line number, file, etc. 427 428 #define heap_locking_asserts_err_msg(_extra_message_) \ 429 err_msg("%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 430 (_extra_message_), \ 431 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 432 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 433 BOOL_TO_STR(Thread::current()->is_VM_thread())) 434 435 #define assert_heap_locked() \ 436 do { \ 437 assert(Heap_lock->owned_by_self(), \ 438 heap_locking_asserts_err_msg("should be holding the Heap_lock")); \ 439 } while (0) 440 441 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 442 do { \ 443 assert(Heap_lock->owned_by_self() || \ 444 (SafepointSynchronize::is_at_safepoint() && \ 445 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 446 heap_locking_asserts_err_msg("should be holding the Heap_lock or " \ 447 "should be at a safepoint")); \ 448 } while (0) 449 450 #define assert_heap_locked_and_not_at_safepoint() \ 451 do { \ 452 assert(Heap_lock->owned_by_self() && \ 453 !SafepointSynchronize::is_at_safepoint(), \ 454 heap_locking_asserts_err_msg("should be holding the Heap_lock and " \ 455 "should not be at a safepoint")); \ 456 } while (0) 457 458 #define assert_heap_not_locked() \ 459 do { \ 460 assert(!Heap_lock->owned_by_self(), \ 461 heap_locking_asserts_err_msg("should not be holding the Heap_lock")); \ 462 } while (0) 463 464 #define assert_heap_not_locked_and_not_at_safepoint() \ 465 do { \ 466 assert(!Heap_lock->owned_by_self() && \ 467 !SafepointSynchronize::is_at_safepoint(), \ 468 heap_locking_asserts_err_msg("should not be holding the Heap_lock and " \ 469 "should not be at a safepoint")); \ 470 } while (0) 471 472 #define assert_at_safepoint(_should_be_vm_thread_) \ 473 do { \ 474 assert(SafepointSynchronize::is_at_safepoint() && \ 475 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 476 heap_locking_asserts_err_msg("should be at a safepoint")); \ 477 } while (0) 478 479 #define assert_not_at_safepoint() \ 480 do { \ 481 assert(!SafepointSynchronize::is_at_safepoint(), \ 482 heap_locking_asserts_err_msg("should not be at a safepoint")); \ 483 } while (0) 484 485 protected: 486 487 // The young region list. 488 YoungList* _young_list; 489 490 // The current policy object for the collector. 491 G1CollectorPolicy* _g1_policy; 492 493 // This is the second level of trying to allocate a new region. If 494 // new_region() didn't find a region on the free_list, this call will 495 // check whether there's anything available on the 496 // secondary_free_list and/or wait for more regions to appear on 497 // that list, if _free_regions_coming is set. 498 HeapRegion* new_region_try_secondary_free_list(); 499 500 // Try to allocate a single non-humongous HeapRegion sufficient for 501 // an allocation of the given word_size. If do_expand is true, 502 // attempt to expand the heap if necessary to satisfy the allocation 503 // request. 504 HeapRegion* new_region(size_t word_size, bool do_expand); 505 506 // Attempt to satisfy a humongous allocation request of the given 507 // size by finding a contiguous set of free regions of num_regions 508 // length and remove them from the master free list. Return the 509 // index of the first region or G1_NULL_HRS_INDEX if the search 510 // was unsuccessful. 511 uint humongous_obj_allocate_find_first(uint num_regions, 512 size_t word_size); 513 514 // Initialize a contiguous set of free regions of length num_regions 515 // and starting at index first so that they appear as a single 516 // humongous region. 517 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 518 uint num_regions, 519 size_t word_size); 520 521 // Attempt to allocate a humongous object of the given size. Return 522 // NULL if unsuccessful. 523 HeapWord* humongous_obj_allocate(size_t word_size); 524 525 // The following two methods, allocate_new_tlab() and 526 // mem_allocate(), are the two main entry points from the runtime 527 // into the G1's allocation routines. They have the following 528 // assumptions: 529 // 530 // * They should both be called outside safepoints. 531 // 532 // * They should both be called without holding the Heap_lock. 533 // 534 // * All allocation requests for new TLABs should go to 535 // allocate_new_tlab(). 536 // 537 // * All non-TLAB allocation requests should go to mem_allocate(). 538 // 539 // * If either call cannot satisfy the allocation request using the 540 // current allocating region, they will try to get a new one. If 541 // this fails, they will attempt to do an evacuation pause and 542 // retry the allocation. 543 // 544 // * If all allocation attempts fail, even after trying to schedule 545 // an evacuation pause, allocate_new_tlab() will return NULL, 546 // whereas mem_allocate() will attempt a heap expansion and/or 547 // schedule a Full GC. 548 // 549 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 550 // should never be called with word_size being humongous. All 551 // humongous allocation requests should go to mem_allocate() which 552 // will satisfy them with a special path. 553 554 virtual HeapWord* allocate_new_tlab(size_t word_size); 555 556 virtual HeapWord* mem_allocate(size_t word_size, 557 bool* gc_overhead_limit_was_exceeded); 558 559 // The following three methods take a gc_count_before_ret 560 // parameter which is used to return the GC count if the method 561 // returns NULL. Given that we are required to read the GC count 562 // while holding the Heap_lock, and these paths will take the 563 // Heap_lock at some point, it's easier to get them to read the GC 564 // count while holding the Heap_lock before they return NULL instead 565 // of the caller (namely: mem_allocate()) having to also take the 566 // Heap_lock just to read the GC count. 567 568 // First-level mutator allocation attempt: try to allocate out of 569 // the mutator alloc region without taking the Heap_lock. This 570 // should only be used for non-humongous allocations. 571 inline HeapWord* attempt_allocation(size_t word_size, 572 unsigned int* gc_count_before_ret, 573 int* gclocker_retry_count_ret); 574 575 // Second-level mutator allocation attempt: take the Heap_lock and 576 // retry the allocation attempt, potentially scheduling a GC 577 // pause. This should only be used for non-humongous allocations. 578 HeapWord* attempt_allocation_slow(size_t word_size, 579 unsigned int* gc_count_before_ret, 580 int* gclocker_retry_count_ret); 581 582 // Takes the Heap_lock and attempts a humongous allocation. It can 583 // potentially schedule a GC pause. 584 HeapWord* attempt_allocation_humongous(size_t word_size, 585 unsigned int* gc_count_before_ret, 586 int* gclocker_retry_count_ret); 587 588 // Allocation attempt that should be called during safepoints (e.g., 589 // at the end of a successful GC). expect_null_mutator_alloc_region 590 // specifies whether the mutator alloc region is expected to be NULL 591 // or not. 592 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 593 bool expect_null_mutator_alloc_region); 594 595 // It dirties the cards that cover the block so that so that the post 596 // write barrier never queues anything when updating objects on this 597 // block. It is assumed (and in fact we assert) that the block 598 // belongs to a young region. 599 inline void dirty_young_block(HeapWord* start, size_t word_size); 600 601 // Allocate blocks during garbage collection. Will ensure an 602 // allocation region, either by picking one or expanding the 603 // heap, and then allocate a block of the given size. The block 604 // may not be a humongous - it must fit into a single heap region. 605 HeapWord* par_allocate_during_gc(GCAllocPurpose purpose, size_t word_size); 606 607 // Ensure that no further allocations can happen in "r", bearing in mind 608 // that parallel threads might be attempting allocations. 609 void par_allocate_remaining_space(HeapRegion* r); 610 611 // Allocation attempt during GC for a survivor object / PLAB. 612 inline HeapWord* survivor_attempt_allocation(size_t word_size); 613 614 // Allocation attempt during GC for an old object / PLAB. 615 inline HeapWord* old_attempt_allocation(size_t word_size); 616 617 // These methods are the "callbacks" from the G1AllocRegion class. 618 619 // For mutator alloc regions. 620 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 621 void retire_mutator_alloc_region(HeapRegion* alloc_region, 622 size_t allocated_bytes); 623 624 // For GC alloc regions. 625 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 626 GCAllocPurpose ap); 627 void retire_gc_alloc_region(HeapRegion* alloc_region, 628 size_t allocated_bytes, GCAllocPurpose ap); 629 630 // - if explicit_gc is true, the GC is for a System.gc() or a heap 631 // inspection request and should collect the entire heap 632 // - if clear_all_soft_refs is true, all soft references should be 633 // cleared during the GC 634 // - if explicit_gc is false, word_size describes the allocation that 635 // the GC should attempt (at least) to satisfy 636 // - it returns false if it is unable to do the collection due to the 637 // GC locker being active, true otherwise 638 bool do_collection(bool explicit_gc, 639 bool clear_all_soft_refs, 640 size_t word_size); 641 642 // Callback from VM_G1CollectFull operation. 643 // Perform a full collection. 644 virtual void do_full_collection(bool clear_all_soft_refs); 645 646 // Resize the heap if necessary after a full collection. If this is 647 // after a collect-for allocation, "word_size" is the allocation size, 648 // and will be considered part of the used portion of the heap. 649 void resize_if_necessary_after_full_collection(size_t word_size); 650 651 // Callback from VM_G1CollectForAllocation operation. 652 // This function does everything necessary/possible to satisfy a 653 // failed allocation request (including collection, expansion, etc.) 654 HeapWord* satisfy_failed_allocation(size_t word_size, bool* succeeded); 655 656 // Attempting to expand the heap sufficiently 657 // to support an allocation of the given "word_size". If 658 // successful, perform the allocation and return the address of the 659 // allocated block, or else "NULL". 660 HeapWord* expand_and_allocate(size_t word_size); 661 662 // Process any reference objects discovered during 663 // an incremental evacuation pause. 664 void process_discovered_references(uint no_of_gc_workers); 665 666 // Enqueue any remaining discovered references 667 // after processing. 668 void enqueue_discovered_references(uint no_of_gc_workers); 669 670 public: 671 672 G1MonitoringSupport* g1mm() { 673 assert(_g1mm != NULL, "should have been initialized"); 674 return _g1mm; 675 } 676 677 // Expand the garbage-first heap by at least the given size (in bytes!). 678 // Returns true if the heap was expanded by the requested amount; 679 // false otherwise. 680 // (Rounds up to a HeapRegion boundary.) 681 bool expand(size_t expand_bytes); 682 683 // Do anything common to GC's. 684 virtual void gc_prologue(bool full); 685 virtual void gc_epilogue(bool full); 686 687 // We register a region with the fast "in collection set" test. We 688 // simply set to true the array slot corresponding to this region. 689 void register_region_with_in_cset_fast_test(HeapRegion* r) { 690 assert(_in_cset_fast_test_base != NULL, "sanity"); 691 assert(r->in_collection_set(), "invariant"); 692 uint index = r->hrs_index(); 693 assert(index < _in_cset_fast_test_length, "invariant"); 694 assert(!_in_cset_fast_test_base[index], "invariant"); 695 _in_cset_fast_test_base[index] = true; 696 } 697 698 // This is a fast test on whether a reference points into the 699 // collection set or not. It does not assume that the reference 700 // points into the heap; if it doesn't, it will return false. 701 bool in_cset_fast_test(oop obj) { 702 assert(_in_cset_fast_test != NULL, "sanity"); 703 if (_g1_committed.contains((HeapWord*) obj)) { 704 // no need to subtract the bottom of the heap from obj, 705 // _in_cset_fast_test is biased 706 uintx index = (uintx) obj >> HeapRegion::LogOfHRGrainBytes; 707 bool ret = _in_cset_fast_test[index]; 708 // let's make sure the result is consistent with what the slower 709 // test returns 710 assert( ret || !obj_in_cs(obj), "sanity"); 711 assert(!ret || obj_in_cs(obj), "sanity"); 712 return ret; 713 } else { 714 return false; 715 } 716 } 717 718 void clear_cset_fast_test() { 719 assert(_in_cset_fast_test_base != NULL, "sanity"); 720 memset(_in_cset_fast_test_base, false, 721 (size_t) _in_cset_fast_test_length * sizeof(bool)); 722 } 723 724 // This is called at the start of either a concurrent cycle or a Full 725 // GC to update the number of old marking cycles started. 726 void increment_old_marking_cycles_started(); 727 728 // This is called at the end of either a concurrent cycle or a Full 729 // GC to update the number of old marking cycles completed. Those two 730 // can happen in a nested fashion, i.e., we start a concurrent 731 // cycle, a Full GC happens half-way through it which ends first, 732 // and then the cycle notices that a Full GC happened and ends 733 // too. The concurrent parameter is a boolean to help us do a bit 734 // tighter consistency checking in the method. If concurrent is 735 // false, the caller is the inner caller in the nesting (i.e., the 736 // Full GC). If concurrent is true, the caller is the outer caller 737 // in this nesting (i.e., the concurrent cycle). Further nesting is 738 // not currently supported. The end of this call also notifies 739 // the FullGCCount_lock in case a Java thread is waiting for a full 740 // GC to happen (e.g., it called System.gc() with 741 // +ExplicitGCInvokesConcurrent). 742 void increment_old_marking_cycles_completed(bool concurrent); 743 744 unsigned int old_marking_cycles_completed() { 745 return _old_marking_cycles_completed; 746 } 747 748 void register_concurrent_cycle_start(jlong start_time); 749 void register_concurrent_cycle_end(); 750 void trace_heap_after_concurrent_cycle(); 751 752 G1YCType yc_type(); 753 754 G1HRPrinter* hr_printer() { return &_hr_printer; } 755 756 protected: 757 758 // Shrink the garbage-first heap by at most the given size (in bytes!). 759 // (Rounds down to a HeapRegion boundary.) 760 virtual void shrink(size_t expand_bytes); 761 void shrink_helper(size_t expand_bytes); 762 763 #if TASKQUEUE_STATS 764 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 765 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 766 void reset_taskqueue_stats(); 767 #endif // TASKQUEUE_STATS 768 769 // Schedule the VM operation that will do an evacuation pause to 770 // satisfy an allocation request of word_size. *succeeded will 771 // return whether the VM operation was successful (it did do an 772 // evacuation pause) or not (another thread beat us to it or the GC 773 // locker was active). Given that we should not be holding the 774 // Heap_lock when we enter this method, we will pass the 775 // gc_count_before (i.e., total_collections()) as a parameter since 776 // it has to be read while holding the Heap_lock. Currently, both 777 // methods that call do_collection_pause() release the Heap_lock 778 // before the call, so it's easy to read gc_count_before just before. 779 HeapWord* do_collection_pause(size_t word_size, 780 unsigned int gc_count_before, 781 bool* succeeded, 782 GCCause::Cause gc_cause); 783 784 // The guts of the incremental collection pause, executed by the vm 785 // thread. It returns false if it is unable to do the collection due 786 // to the GC locker being active, true otherwise 787 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 788 789 // Actually do the work of evacuating the collection set. 790 void evacuate_collection_set(EvacuationInfo& evacuation_info); 791 792 // The g1 remembered set of the heap. 793 G1RemSet* _g1_rem_set; 794 // And it's mod ref barrier set, used to track updates for the above. 795 ModRefBarrierSet* _mr_bs; 796 797 // A set of cards that cover the objects for which the Rsets should be updated 798 // concurrently after the collection. 799 DirtyCardQueueSet _dirty_card_queue_set; 800 801 // The closure used to refine a single card. 802 RefineCardTableEntryClosure* _refine_cte_cl; 803 804 // A function to check the consistency of dirty card logs. 805 void check_ct_logs_at_safepoint(); 806 807 // A DirtyCardQueueSet that is used to hold cards that contain 808 // references into the current collection set. This is used to 809 // update the remembered sets of the regions in the collection 810 // set in the event of an evacuation failure. 811 DirtyCardQueueSet _into_cset_dirty_card_queue_set; 812 813 // After a collection pause, make the regions in the CS into free 814 // regions. 815 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info); 816 817 // Abandon the current collection set without recording policy 818 // statistics or updating free lists. 819 void abandon_collection_set(HeapRegion* cs_head); 820 821 // Applies "scan_non_heap_roots" to roots outside the heap, 822 // "scan_rs" to roots inside the heap (having done "set_region" to 823 // indicate the region in which the root resides), 824 // and does "scan_metadata" If "scan_rs" is 825 // NULL, then this step is skipped. The "worker_i" 826 // param is for use with parallel roots processing, and should be 827 // the "i" of the calling parallel worker thread's work(i) function. 828 // In the sequential case this param will be ignored. 829 void g1_process_strong_roots(bool is_scavenging, 830 ScanningOption so, 831 OopClosure* scan_non_heap_roots, 832 OopsInHeapRegionClosure* scan_rs, 833 G1KlassScanClosure* scan_klasses, 834 int worker_i); 835 836 // Apply "blk" to all the weak roots of the system. These include 837 // JNI weak roots, the code cache, system dictionary, symbol table, 838 // string table, and referents of reachable weak refs. 839 void g1_process_weak_roots(OopClosure* root_closure); 840 841 // Frees a non-humongous region by initializing its contents and 842 // adding it to the free list that's passed as a parameter (this is 843 // 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_region(HeapRegion* hr, 848 size_t* pre_used, 849 FreeRegionList* free_list, 850 bool par); 851 852 // Frees a humongous region by collapsing it into individual regions 853 // and calling free_region() for each of them. The freed regions 854 // will be added to the free list that's passed as a parameter (this 855 // is usually a local list which will be appended to the master free 856 // list later). The used bytes of freed regions are accumulated in 857 // pre_used. If par is true, the region's RSet will not be freed 858 // up. The assumption is that this will be done later. 859 void free_humongous_region(HeapRegion* hr, 860 size_t* pre_used, 861 FreeRegionList* free_list, 862 HumongousRegionSet* humongous_proxy_set, 863 bool par); 864 865 // Notifies all the necessary spaces that the committed space has 866 // been updated (either expanded or shrunk). It should be called 867 // after _g1_storage is updated. 868 void update_committed_space(HeapWord* old_end, HeapWord* new_end); 869 870 // The concurrent marker (and the thread it runs in.) 871 ConcurrentMark* _cm; 872 ConcurrentMarkThread* _cmThread; 873 bool _mark_in_progress; 874 875 // The concurrent refiner. 876 ConcurrentG1Refine* _cg1r; 877 878 // The parallel task queues 879 RefToScanQueueSet *_task_queues; 880 881 // True iff a evacuation has failed in the current collection. 882 bool _evacuation_failed; 883 884 EvacuationFailedInfo* _evacuation_failed_info_array; 885 886 // Failed evacuations cause some logical from-space objects to have 887 // forwarding pointers to themselves. Reset them. 888 void remove_self_forwarding_pointers(); 889 890 // Together, these store an object with a preserved mark, and its mark value. 891 Stack<oop, mtGC> _objs_with_preserved_marks; 892 Stack<markOop, mtGC> _preserved_marks_of_objs; 893 894 // Preserve the mark of "obj", if necessary, in preparation for its mark 895 // word being overwritten with a self-forwarding-pointer. 896 void preserve_mark_if_necessary(oop obj, markOop m); 897 898 // The stack of evac-failure objects left to be scanned. 899 GrowableArray<oop>* _evac_failure_scan_stack; 900 // The closure to apply to evac-failure objects. 901 902 OopsInHeapRegionClosure* _evac_failure_closure; 903 // Set the field above. 904 void 905 set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_closure) { 906 _evac_failure_closure = evac_failure_closure; 907 } 908 909 // Push "obj" on the scan stack. 910 void push_on_evac_failure_scan_stack(oop obj); 911 // Process scan stack entries until the stack is empty. 912 void drain_evac_failure_scan_stack(); 913 // True iff an invocation of "drain_scan_stack" is in progress; to 914 // prevent unnecessary recursion. 915 bool _drain_in_progress; 916 917 // Do any necessary initialization for evacuation-failure handling. 918 // "cl" is the closure that will be used to process evac-failure 919 // objects. 920 void init_for_evac_failure(OopsInHeapRegionClosure* cl); 921 // Do any necessary cleanup for evacuation-failure handling data 922 // structures. 923 void finalize_for_evac_failure(); 924 925 // An attempt to evacuate "obj" has failed; take necessary steps. 926 oop handle_evacuation_failure_par(G1ParScanThreadState* _par_scan_state, oop obj); 927 void handle_evacuation_failure_common(oop obj, markOop m); 928 929 #ifndef PRODUCT 930 // Support for forcing evacuation failures. Analogous to 931 // PromotionFailureALot for the other collectors. 932 933 // Records whether G1EvacuationFailureALot should be in effect 934 // for the current GC 935 bool _evacuation_failure_alot_for_current_gc; 936 937 // Used to record the GC number for interval checking when 938 // determining whether G1EvaucationFailureALot is in effect 939 // for the current GC. 940 size_t _evacuation_failure_alot_gc_number; 941 942 // Count of the number of evacuations between failures. 943 volatile size_t _evacuation_failure_alot_count; 944 945 // Set whether G1EvacuationFailureALot should be in effect 946 // for the current GC (based upon the type of GC and which 947 // command line flags are set); 948 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 949 bool during_initial_mark, 950 bool during_marking); 951 952 inline void set_evacuation_failure_alot_for_current_gc(); 953 954 // Return true if it's time to cause an evacuation failure. 955 inline bool evacuation_should_fail(); 956 957 // Reset the G1EvacuationFailureALot counters. Should be called at 958 // the end of an evacuation pause in which an evacuation failure occurred. 959 inline void reset_evacuation_should_fail(); 960 #endif // !PRODUCT 961 962 // ("Weak") Reference processing support. 963 // 964 // G1 has 2 instances of the reference processor class. One 965 // (_ref_processor_cm) handles reference object discovery 966 // and subsequent processing during concurrent marking cycles. 967 // 968 // The other (_ref_processor_stw) handles reference object 969 // discovery and processing during full GCs and incremental 970 // evacuation pauses. 971 // 972 // During an incremental pause, reference discovery will be 973 // temporarily disabled for _ref_processor_cm and will be 974 // enabled for _ref_processor_stw. At the end of the evacuation 975 // pause references discovered by _ref_processor_stw will be 976 // processed and discovery will be disabled. The previous 977 // setting for reference object discovery for _ref_processor_cm 978 // will be re-instated. 979 // 980 // At the start of marking: 981 // * Discovery by the CM ref processor is verified to be inactive 982 // and it's discovered lists are empty. 983 // * Discovery by the CM ref processor is then enabled. 984 // 985 // At the end of marking: 986 // * Any references on the CM ref processor's discovered 987 // lists are processed (possibly MT). 988 // 989 // At the start of full GC we: 990 // * Disable discovery by the CM ref processor and 991 // empty CM ref processor's discovered lists 992 // (without processing any entries). 993 // * Verify that the STW ref processor is inactive and it's 994 // discovered lists are empty. 995 // * Temporarily set STW ref processor discovery as single threaded. 996 // * Temporarily clear the STW ref processor's _is_alive_non_header 997 // field. 998 // * Finally enable discovery by the STW ref processor. 999 // 1000 // The STW ref processor is used to record any discovered 1001 // references during the full GC. 1002 // 1003 // At the end of a full GC we: 1004 // * Enqueue any reference objects discovered by the STW ref processor 1005 // that have non-live referents. This has the side-effect of 1006 // making the STW ref processor inactive by disabling discovery. 1007 // * Verify that the CM ref processor is still inactive 1008 // and no references have been placed on it's discovered 1009 // lists (also checked as a precondition during initial marking). 1010 1011 // The (stw) reference processor... 1012 ReferenceProcessor* _ref_processor_stw; 1013 1014 STWGCTimer* _gc_timer_stw; 1015 ConcurrentGCTimer* _gc_timer_cm; 1016 1017 G1OldTracer* _gc_tracer_cm; 1018 G1NewTracer* _gc_tracer_stw; 1019 1020 // During reference object discovery, the _is_alive_non_header 1021 // closure (if non-null) is applied to the referent object to 1022 // determine whether the referent is live. If so then the 1023 // reference object does not need to be 'discovered' and can 1024 // be treated as a regular oop. This has the benefit of reducing 1025 // the number of 'discovered' reference objects that need to 1026 // be processed. 1027 // 1028 // Instance of the is_alive closure for embedding into the 1029 // STW reference processor as the _is_alive_non_header field. 1030 // Supplying a value for the _is_alive_non_header field is 1031 // optional but doing so prevents unnecessary additions to 1032 // the discovered lists during reference discovery. 1033 G1STWIsAliveClosure _is_alive_closure_stw; 1034 1035 // The (concurrent marking) reference processor... 1036 ReferenceProcessor* _ref_processor_cm; 1037 1038 // Instance of the concurrent mark is_alive closure for embedding 1039 // into the Concurrent Marking reference processor as the 1040 // _is_alive_non_header field. Supplying a value for the 1041 // _is_alive_non_header field is optional but doing so prevents 1042 // unnecessary additions to the discovered lists during reference 1043 // discovery. 1044 G1CMIsAliveClosure _is_alive_closure_cm; 1045 1046 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 1047 HeapRegion** _worker_cset_start_region; 1048 1049 // Time stamp to validate the regions recorded in the cache 1050 // used by G1CollectedHeap::start_cset_region_for_worker(). 1051 // The heap region entry for a given worker is valid iff 1052 // the associated time stamp value matches the current value 1053 // of G1CollectedHeap::_gc_time_stamp. 1054 unsigned int* _worker_cset_start_region_time_stamp; 1055 1056 enum G1H_process_strong_roots_tasks { 1057 G1H_PS_filter_satb_buffers, 1058 G1H_PS_refProcessor_oops_do, 1059 // Leave this one last. 1060 G1H_PS_NumElements 1061 }; 1062 1063 SubTasksDone* _process_strong_tasks; 1064 1065 volatile bool _free_regions_coming; 1066 1067 public: 1068 1069 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; } 1070 1071 void set_refine_cte_cl_concurrency(bool concurrent); 1072 1073 RefToScanQueue *task_queue(int i) const; 1074 1075 // A set of cards where updates happened during the GC 1076 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 1077 1078 // A DirtyCardQueueSet that is used to hold cards that contain 1079 // references into the current collection set. This is used to 1080 // update the remembered sets of the regions in the collection 1081 // set in the event of an evacuation failure. 1082 DirtyCardQueueSet& into_cset_dirty_card_queue_set() 1083 { return _into_cset_dirty_card_queue_set; } 1084 1085 // Create a G1CollectedHeap with the specified policy. 1086 // Must call the initialize method afterwards. 1087 // May not return if something goes wrong. 1088 G1CollectedHeap(G1CollectorPolicy* policy); 1089 1090 // Initialize the G1CollectedHeap to have the initial and 1091 // maximum sizes and remembered and barrier sets 1092 // specified by the policy object. 1093 jint initialize(); 1094 1095 // Return the (conservative) maximum heap alignment for any G1 heap 1096 static size_t conservative_max_heap_alignment(); 1097 1098 // Initialize weak reference processing. 1099 virtual void ref_processing_init(); 1100 1101 void set_par_threads(uint t) { 1102 SharedHeap::set_par_threads(t); 1103 // Done in SharedHeap but oddly there are 1104 // two _process_strong_tasks's in a G1CollectedHeap 1105 // so do it here too. 1106 _process_strong_tasks->set_n_threads(t); 1107 } 1108 1109 // Set _n_par_threads according to a policy TBD. 1110 void set_par_threads(); 1111 1112 void set_n_termination(int t) { 1113 _process_strong_tasks->set_n_threads(t); 1114 } 1115 1116 virtual CollectedHeap::Name kind() const { 1117 return CollectedHeap::G1CollectedHeap; 1118 } 1119 1120 // The current policy object for the collector. 1121 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 1122 1123 virtual CollectorPolicy* collector_policy() const { return (CollectorPolicy*) g1_policy(); } 1124 1125 // Adaptive size policy. No such thing for g1. 1126 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 1127 1128 // The rem set and barrier set. 1129 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 1130 ModRefBarrierSet* mr_bs() const { return _mr_bs; } 1131 1132 unsigned get_gc_time_stamp() { 1133 return _gc_time_stamp; 1134 } 1135 1136 void reset_gc_time_stamp() { 1137 _gc_time_stamp = 0; 1138 OrderAccess::fence(); 1139 // Clear the cached CSet starting regions and time stamps. 1140 // Their validity is dependent on the GC timestamp. 1141 clear_cset_start_regions(); 1142 } 1143 1144 void check_gc_time_stamps() PRODUCT_RETURN; 1145 1146 void increment_gc_time_stamp() { 1147 ++_gc_time_stamp; 1148 OrderAccess::fence(); 1149 } 1150 1151 // Reset the given region's GC timestamp. If it's starts humongous, 1152 // also reset the GC timestamp of its corresponding 1153 // continues humongous regions too. 1154 void reset_gc_time_stamps(HeapRegion* hr); 1155 1156 void iterate_dirty_card_closure(CardTableEntryClosure* cl, 1157 DirtyCardQueue* into_cset_dcq, 1158 bool concurrent, int worker_i); 1159 1160 // The shared block offset table array. 1161 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1162 1163 // Reference Processing accessors 1164 1165 // The STW reference processor.... 1166 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1167 1168 // The Concurrent Marking reference processor... 1169 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1170 1171 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } 1172 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } 1173 1174 virtual size_t capacity() const; 1175 virtual size_t used() const; 1176 // This should be called when we're not holding the heap lock. The 1177 // result might be a bit inaccurate. 1178 size_t used_unlocked() const; 1179 size_t recalculate_used() const; 1180 1181 // These virtual functions do the actual allocation. 1182 // Some heaps may offer a contiguous region for shared non-blocking 1183 // allocation, via inlined code (by exporting the address of the top and 1184 // end fields defining the extent of the contiguous allocation region.) 1185 // But G1CollectedHeap doesn't yet support this. 1186 1187 // Return an estimate of the maximum allocation that could be performed 1188 // without triggering any collection or expansion activity. In a 1189 // generational collector, for example, this is probably the largest 1190 // allocation that could be supported (without expansion) in the youngest 1191 // generation. It is "unsafe" because no locks are taken; the result 1192 // should be treated as an approximation, not a guarantee, for use in 1193 // heuristic resizing decisions. 1194 virtual size_t unsafe_max_alloc(); 1195 1196 virtual bool is_maximal_no_gc() const { 1197 return _g1_storage.uncommitted_size() == 0; 1198 } 1199 1200 // The total number of regions in the heap. 1201 uint n_regions() { return _hrs.length(); } 1202 1203 // The max number of regions in the heap. 1204 uint max_regions() { return _hrs.max_length(); } 1205 1206 // The number of regions that are completely free. 1207 uint free_regions() { return _free_list.length(); } 1208 1209 // The number of regions that are not completely free. 1210 uint used_regions() { return n_regions() - free_regions(); } 1211 1212 // The number of regions available for "regular" expansion. 1213 uint expansion_regions() { return _expansion_regions; } 1214 1215 // Factory method for HeapRegion instances. It will return NULL if 1216 // the allocation fails. 1217 HeapRegion* new_heap_region(uint hrs_index, HeapWord* bottom); 1218 1219 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1220 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1221 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1222 void verify_dirty_young_regions() PRODUCT_RETURN; 1223 1224 // verify_region_sets() performs verification over the region 1225 // lists. It will be compiled in the product code to be used when 1226 // necessary (i.e., during heap verification). 1227 void verify_region_sets(); 1228 1229 // verify_region_sets_optional() is planted in the code for 1230 // list verification in non-product builds (and it can be enabled in 1231 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1). 1232 #if HEAP_REGION_SET_FORCE_VERIFY 1233 void verify_region_sets_optional() { 1234 verify_region_sets(); 1235 } 1236 #else // HEAP_REGION_SET_FORCE_VERIFY 1237 void verify_region_sets_optional() { } 1238 #endif // HEAP_REGION_SET_FORCE_VERIFY 1239 1240 #ifdef ASSERT 1241 bool is_on_master_free_list(HeapRegion* hr) { 1242 return hr->containing_set() == &_free_list; 1243 } 1244 1245 bool is_in_humongous_set(HeapRegion* hr) { 1246 return hr->containing_set() == &_humongous_set; 1247 } 1248 #endif // ASSERT 1249 1250 // Wrapper for the region list operations that can be called from 1251 // methods outside this class. 1252 1253 void secondary_free_list_add_as_tail(FreeRegionList* list) { 1254 _secondary_free_list.add_as_tail(list); 1255 } 1256 1257 void append_secondary_free_list() { 1258 _free_list.add_as_head(&_secondary_free_list); 1259 } 1260 1261 void append_secondary_free_list_if_not_empty_with_lock() { 1262 // If the secondary free list looks empty there's no reason to 1263 // take the lock and then try to append it. 1264 if (!_secondary_free_list.is_empty()) { 1265 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1266 append_secondary_free_list(); 1267 } 1268 } 1269 1270 void old_set_remove(HeapRegion* hr) { 1271 _old_set.remove(hr); 1272 } 1273 1274 size_t non_young_capacity_bytes() { 1275 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1276 } 1277 1278 void set_free_regions_coming(); 1279 void reset_free_regions_coming(); 1280 bool free_regions_coming() { return _free_regions_coming; } 1281 void wait_while_free_regions_coming(); 1282 1283 // Determine whether the given region is one that we are using as an 1284 // old GC alloc region. 1285 bool is_old_gc_alloc_region(HeapRegion* hr) { 1286 return hr == _retained_old_gc_alloc_region; 1287 } 1288 1289 // Perform a collection of the heap; intended for use in implementing 1290 // "System.gc". This probably implies as full a collection as the 1291 // "CollectedHeap" supports. 1292 virtual void collect(GCCause::Cause cause); 1293 1294 // The same as above but assume that the caller holds the Heap_lock. 1295 void collect_locked(GCCause::Cause cause); 1296 1297 // True iff an evacuation has failed in the most-recent collection. 1298 bool evacuation_failed() { return _evacuation_failed; } 1299 1300 // It will free a region if it has allocated objects in it that are 1301 // all dead. It calls either free_region() or 1302 // free_humongous_region() depending on the type of the region that 1303 // is passed to it. 1304 void free_region_if_empty(HeapRegion* hr, 1305 size_t* pre_used, 1306 FreeRegionList* free_list, 1307 OldRegionSet* old_proxy_set, 1308 HumongousRegionSet* humongous_proxy_set, 1309 HRRSCleanupTask* hrrs_cleanup_task, 1310 bool par); 1311 1312 // It appends the free list to the master free list and updates the 1313 // master humongous list according to the contents of the proxy 1314 // list. It also adjusts the total used bytes according to pre_used 1315 // (if par is true, it will do so by taking the ParGCRareEvent_lock). 1316 void update_sets_after_freeing_regions(size_t pre_used, 1317 FreeRegionList* free_list, 1318 OldRegionSet* old_proxy_set, 1319 HumongousRegionSet* humongous_proxy_set, 1320 bool par); 1321 1322 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1323 virtual bool is_in(const void* p) const; 1324 1325 // Return "TRUE" iff the given object address is within the collection 1326 // set. 1327 inline bool obj_in_cs(oop obj); 1328 1329 // Return "TRUE" iff the given object address is in the reserved 1330 // region of g1. 1331 bool is_in_g1_reserved(const void* p) const { 1332 return _g1_reserved.contains(p); 1333 } 1334 1335 // Returns a MemRegion that corresponds to the space that has been 1336 // reserved for the heap 1337 MemRegion g1_reserved() { 1338 return _g1_reserved; 1339 } 1340 1341 // Returns a MemRegion that corresponds to the space that has been 1342 // committed in the heap 1343 MemRegion g1_committed() { 1344 return _g1_committed; 1345 } 1346 1347 virtual bool is_in_closed_subset(const void* p) const; 1348 1349 // This resets the card table to all zeros. It is used after 1350 // a collection pause which used the card table to claim cards. 1351 void cleanUpCardTable(); 1352 1353 // Iteration functions. 1354 1355 // Iterate over all the ref-containing fields of all objects, calling 1356 // "cl.do_oop" on each. 1357 virtual void oop_iterate(ExtendedOopClosure* cl); 1358 1359 // Same as above, restricted to a memory region. 1360 void oop_iterate(MemRegion mr, ExtendedOopClosure* cl); 1361 1362 // Iterate over all objects, calling "cl.do_object" on each. 1363 virtual void object_iterate(ObjectClosure* cl); 1364 1365 virtual void safe_object_iterate(ObjectClosure* cl) { 1366 object_iterate(cl); 1367 } 1368 1369 // Iterate over all spaces in use in the heap, in ascending address order. 1370 virtual void space_iterate(SpaceClosure* cl); 1371 1372 // Iterate over heap regions, in address order, terminating the 1373 // iteration early if the "doHeapRegion" method returns "true". 1374 void heap_region_iterate(HeapRegionClosure* blk) const; 1375 1376 // Return the region with the given index. It assumes the index is valid. 1377 HeapRegion* region_at(uint index) const { return _hrs.at(index); } 1378 1379 // Divide the heap region sequence into "chunks" of some size (the number 1380 // of regions divided by the number of parallel threads times some 1381 // overpartition factor, currently 4). Assumes that this will be called 1382 // in parallel by ParallelGCThreads worker threads with discinct worker 1383 // ids in the range [0..max(ParallelGCThreads-1, 1)], that all parallel 1384 // calls will use the same "claim_value", and that that claim value is 1385 // different from the claim_value of any heap region before the start of 1386 // the iteration. Applies "blk->doHeapRegion" to each of the regions, by 1387 // attempting to claim the first region in each chunk, and, if 1388 // successful, applying the closure to each region in the chunk (and 1389 // setting the claim value of the second and subsequent regions of the 1390 // chunk.) For now requires that "doHeapRegion" always returns "false", 1391 // i.e., that a closure never attempt to abort a traversal. 1392 void heap_region_par_iterate_chunked(HeapRegionClosure* blk, 1393 uint worker, 1394 uint no_of_par_workers, 1395 jint claim_value); 1396 1397 // It resets all the region claim values to the default. 1398 void reset_heap_region_claim_values(); 1399 1400 // Resets the claim values of regions in the current 1401 // collection set to the default. 1402 void reset_cset_heap_region_claim_values(); 1403 1404 #ifdef ASSERT 1405 bool check_heap_region_claim_values(jint claim_value); 1406 1407 // Same as the routine above but only checks regions in the 1408 // current collection set. 1409 bool check_cset_heap_region_claim_values(jint claim_value); 1410 #endif // ASSERT 1411 1412 // Clear the cached cset start regions and (more importantly) 1413 // the time stamps. Called when we reset the GC time stamp. 1414 void clear_cset_start_regions(); 1415 1416 // Given the id of a worker, obtain or calculate a suitable 1417 // starting region for iterating over the current collection set. 1418 HeapRegion* start_cset_region_for_worker(int worker_i); 1419 1420 // This is a convenience method that is used by the 1421 // HeapRegionIterator classes to calculate the starting region for 1422 // each worker so that they do not all start from the same region. 1423 HeapRegion* start_region_for_worker(uint worker_i, uint no_of_par_workers); 1424 1425 // Iterate over the regions (if any) in the current collection set. 1426 void collection_set_iterate(HeapRegionClosure* blk); 1427 1428 // As above but starting from region r 1429 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1430 1431 // Returns the first (lowest address) compactible space in the heap. 1432 virtual CompactibleSpace* first_compactible_space(); 1433 1434 // A CollectedHeap will contain some number of spaces. This finds the 1435 // space containing a given address, or else returns NULL. 1436 virtual Space* space_containing(const void* addr) const; 1437 1438 // A G1CollectedHeap will contain some number of heap regions. This 1439 // finds the region containing a given address, or else returns NULL. 1440 template <class T> 1441 inline HeapRegion* heap_region_containing(const T addr) const; 1442 1443 // Like the above, but requires "addr" to be in the heap (to avoid a 1444 // null-check), and unlike the above, may return an continuing humongous 1445 // region. 1446 template <class T> 1447 inline HeapRegion* heap_region_containing_raw(const T addr) const; 1448 1449 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1450 // each address in the (reserved) heap is a member of exactly 1451 // one block. The defining characteristic of a block is that it is 1452 // possible to find its size, and thus to progress forward to the next 1453 // block. (Blocks may be of different sizes.) Thus, blocks may 1454 // represent Java objects, or they might be free blocks in a 1455 // free-list-based heap (or subheap), as long as the two kinds are 1456 // distinguishable and the size of each is determinable. 1457 1458 // Returns the address of the start of the "block" that contains the 1459 // address "addr". We say "blocks" instead of "object" since some heaps 1460 // may not pack objects densely; a chunk may either be an object or a 1461 // non-object. 1462 virtual HeapWord* block_start(const void* addr) const; 1463 1464 // Requires "addr" to be the start of a chunk, and returns its size. 1465 // "addr + size" is required to be the start of a new chunk, or the end 1466 // of the active area of the heap. 1467 virtual size_t block_size(const HeapWord* addr) const; 1468 1469 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1470 // the block is an object. 1471 virtual bool block_is_obj(const HeapWord* addr) const; 1472 1473 // Does this heap support heap inspection? (+PrintClassHistogram) 1474 virtual bool supports_heap_inspection() const { return true; } 1475 1476 // Section on thread-local allocation buffers (TLABs) 1477 // See CollectedHeap for semantics. 1478 1479 virtual bool supports_tlab_allocation() const; 1480 virtual size_t tlab_capacity(Thread* thr) const; 1481 virtual size_t unsafe_max_tlab_alloc(Thread* thr) const; 1482 1483 // Can a compiler initialize a new object without store barriers? 1484 // This permission only extends from the creation of a new object 1485 // via a TLAB up to the first subsequent safepoint. If such permission 1486 // is granted for this heap type, the compiler promises to call 1487 // defer_store_barrier() below on any slow path allocation of 1488 // a new object for which such initializing store barriers will 1489 // have been elided. G1, like CMS, allows this, but should be 1490 // ready to provide a compensating write barrier as necessary 1491 // if that storage came out of a non-young region. The efficiency 1492 // of this implementation depends crucially on being able to 1493 // answer very efficiently in constant time whether a piece of 1494 // storage in the heap comes from a young region or not. 1495 // See ReduceInitialCardMarks. 1496 virtual bool can_elide_tlab_store_barriers() const { 1497 return true; 1498 } 1499 1500 virtual bool card_mark_must_follow_store() const { 1501 return true; 1502 } 1503 1504 bool is_in_young(const oop obj) { 1505 HeapRegion* hr = heap_region_containing(obj); 1506 return hr != NULL && hr->is_young(); 1507 } 1508 1509 #ifdef ASSERT 1510 virtual bool is_in_partial_collection(const void* p); 1511 #endif 1512 1513 virtual bool is_scavengable(const void* addr); 1514 1515 // We don't need barriers for initializing stores to objects 1516 // in the young gen: for the SATB pre-barrier, there is no 1517 // pre-value that needs to be remembered; for the remembered-set 1518 // update logging post-barrier, we don't maintain remembered set 1519 // information for young gen objects. 1520 virtual bool can_elide_initializing_store_barrier(oop new_obj) { 1521 return is_in_young(new_obj); 1522 } 1523 1524 // Returns "true" iff the given word_size is "very large". 1525 static bool isHumongous(size_t word_size) { 1526 // Note this has to be strictly greater-than as the TLABs 1527 // are capped at the humongous thresold and we want to 1528 // ensure that we don't try to allocate a TLAB as 1529 // humongous and that we don't allocate a humongous 1530 // object in a TLAB. 1531 return word_size > _humongous_object_threshold_in_words; 1532 } 1533 1534 // Update mod union table with the set of dirty cards. 1535 void updateModUnion(); 1536 1537 // Set the mod union bits corresponding to the given memRegion. Note 1538 // that this is always a safe operation, since it doesn't clear any 1539 // bits. 1540 void markModUnionRange(MemRegion mr); 1541 1542 // Records the fact that a marking phase is no longer in progress. 1543 void set_marking_complete() { 1544 _mark_in_progress = false; 1545 } 1546 void set_marking_started() { 1547 _mark_in_progress = true; 1548 } 1549 bool mark_in_progress() { 1550 return _mark_in_progress; 1551 } 1552 1553 // Print the maximum heap capacity. 1554 virtual size_t max_capacity() const; 1555 1556 virtual jlong millis_since_last_gc(); 1557 1558 1559 // Convenience function to be used in situations where the heap type can be 1560 // asserted to be this type. 1561 static G1CollectedHeap* heap(); 1562 1563 void set_region_short_lived_locked(HeapRegion* hr); 1564 // add appropriate methods for any other surv rate groups 1565 1566 YoungList* young_list() { return _young_list; } 1567 1568 // debugging 1569 bool check_young_list_well_formed() { 1570 return _young_list->check_list_well_formed(); 1571 } 1572 1573 bool check_young_list_empty(bool check_heap, 1574 bool check_sample = true); 1575 1576 // *** Stuff related to concurrent marking. It's not clear to me that so 1577 // many of these need to be public. 1578 1579 // The functions below are helper functions that a subclass of 1580 // "CollectedHeap" can use in the implementation of its virtual 1581 // functions. 1582 // This performs a concurrent marking of the live objects in a 1583 // bitmap off to the side. 1584 void doConcurrentMark(); 1585 1586 bool isMarkedPrev(oop obj) const; 1587 bool isMarkedNext(oop obj) const; 1588 1589 // Determine if an object is dead, given the object and also 1590 // the region to which the object belongs. An object is dead 1591 // iff a) it was not allocated since the last mark and b) it 1592 // is not marked. 1593 1594 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1595 return 1596 !hr->obj_allocated_since_prev_marking(obj) && 1597 !isMarkedPrev(obj); 1598 } 1599 1600 // This function returns true when an object has been 1601 // around since the previous marking and hasn't yet 1602 // been marked during this marking. 1603 1604 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1605 return 1606 !hr->obj_allocated_since_next_marking(obj) && 1607 !isMarkedNext(obj); 1608 } 1609 1610 // Determine if an object is dead, given only the object itself. 1611 // This will find the region to which the object belongs and 1612 // then call the region version of the same function. 1613 1614 // Added if it is NULL it isn't dead. 1615 1616 bool is_obj_dead(const oop obj) const { 1617 const HeapRegion* hr = heap_region_containing(obj); 1618 if (hr == NULL) { 1619 if (obj == NULL) return false; 1620 else return true; 1621 } 1622 else return is_obj_dead(obj, hr); 1623 } 1624 1625 bool is_obj_ill(const oop obj) const { 1626 const HeapRegion* hr = heap_region_containing(obj); 1627 if (hr == NULL) { 1628 if (obj == NULL) return false; 1629 else return true; 1630 } 1631 else return is_obj_ill(obj, hr); 1632 } 1633 1634 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1635 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1636 bool is_marked(oop obj, VerifyOption vo); 1637 const char* top_at_mark_start_str(VerifyOption vo); 1638 1639 ConcurrentMark* concurrent_mark() const { return _cm; } 1640 1641 // Refinement 1642 1643 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1644 1645 // The dirty cards region list is used to record a subset of regions 1646 // whose cards need clearing. The list if populated during the 1647 // remembered set scanning and drained during the card table 1648 // cleanup. Although the methods are reentrant, population/draining 1649 // phases must not overlap. For synchronization purposes the last 1650 // element on the list points to itself. 1651 HeapRegion* _dirty_cards_region_list; 1652 void push_dirty_cards_region(HeapRegion* hr); 1653 HeapRegion* pop_dirty_cards_region(); 1654 1655 // Optimized nmethod scanning support routines 1656 1657 // Register the given nmethod with the G1 heap 1658 virtual void register_nmethod(nmethod* nm); 1659 1660 // Unregister the given nmethod from the G1 heap 1661 virtual void unregister_nmethod(nmethod* nm); 1662 1663 // Migrate the nmethods in the code root lists of the regions 1664 // in the collection set to regions in to-space. In the event 1665 // of an evacuation failure, nmethods that reference objects 1666 // that were not successfullly evacuated are not migrated. 1667 void migrate_strong_code_roots(); 1668 1669 // During an initial mark pause, mark all the code roots that 1670 // point into regions *not* in the collection set. 1671 void mark_strong_code_roots(uint worker_id); 1672 1673 // Rebuild the stong code root lists for each region 1674 // after a full GC 1675 void rebuild_strong_code_roots(); 1676 1677 // Verification 1678 1679 // The following is just to alert the verification code 1680 // that a full collection has occurred and that the 1681 // remembered sets are no longer up to date. 1682 bool _full_collection; 1683 void set_full_collection() { _full_collection = true;} 1684 void clear_full_collection() {_full_collection = false;} 1685 bool full_collection() {return _full_collection;} 1686 1687 // Perform any cleanup actions necessary before allowing a verification. 1688 virtual void prepare_for_verify(); 1689 1690 // Perform verification. 1691 1692 // vo == UsePrevMarking -> use "prev" marking information, 1693 // vo == UseNextMarking -> use "next" marking information 1694 // vo == UseMarkWord -> use the mark word in the object header 1695 // 1696 // NOTE: Only the "prev" marking information is guaranteed to be 1697 // consistent most of the time, so most calls to this should use 1698 // vo == UsePrevMarking. 1699 // Currently, there is only one case where this is called with 1700 // vo == UseNextMarking, which is to verify the "next" marking 1701 // information at the end of remark. 1702 // Currently there is only one place where this is called with 1703 // vo == UseMarkWord, which is to verify the marking during a 1704 // full GC. 1705 void verify(bool silent, VerifyOption vo); 1706 1707 // Override; it uses the "prev" marking information 1708 virtual void verify(bool silent); 1709 1710 // The methods below are here for convenience and dispatch the 1711 // appropriate method depending on value of the given VerifyOption 1712 // parameter. The values for that parameter, and their meanings, 1713 // are the same as those above. 1714 1715 bool is_obj_dead_cond(const oop obj, 1716 const HeapRegion* hr, 1717 const VerifyOption vo) const { 1718 switch (vo) { 1719 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr); 1720 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr); 1721 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 1722 default: ShouldNotReachHere(); 1723 } 1724 return false; // keep some compilers happy 1725 } 1726 1727 bool is_obj_dead_cond(const oop obj, 1728 const VerifyOption vo) const { 1729 switch (vo) { 1730 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj); 1731 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj); 1732 case VerifyOption_G1UseMarkWord: return !obj->is_gc_marked(); 1733 default: ShouldNotReachHere(); 1734 } 1735 return false; // keep some compilers happy 1736 } 1737 1738 // Printing 1739 1740 virtual void print_on(outputStream* st) const; 1741 virtual void print_extended_on(outputStream* st) const; 1742 virtual void print_on_error(outputStream* st) const; 1743 1744 virtual void print_gc_threads_on(outputStream* st) const; 1745 virtual void gc_threads_do(ThreadClosure* tc) const; 1746 1747 // Override 1748 void print_tracing_info() const; 1749 1750 // The following two methods are helpful for debugging RSet issues. 1751 void print_cset_rsets() PRODUCT_RETURN; 1752 void print_all_rsets() PRODUCT_RETURN; 1753 1754 public: 1755 void stop_conc_gc_threads(); 1756 1757 size_t pending_card_num(); 1758 size_t cards_scanned(); 1759 1760 protected: 1761 size_t _max_heap_capacity; 1762 }; 1763 1764 class G1ParGCAllocBuffer: public ParGCAllocBuffer { 1765 private: 1766 bool _retired; 1767 1768 public: 1769 G1ParGCAllocBuffer(size_t gclab_word_size); 1770 1771 void set_buf(HeapWord* buf) { 1772 ParGCAllocBuffer::set_buf(buf); 1773 _retired = false; 1774 } 1775 1776 void retire(bool end_of_gc, bool retain) { 1777 if (_retired) 1778 return; 1779 ParGCAllocBuffer::retire(end_of_gc, retain); 1780 _retired = true; 1781 } 1782 1783 bool is_retired() { 1784 return _retired; 1785 } 1786 }; 1787 1788 class G1ParGCAllocBufferContainer { 1789 protected: 1790 static int const _priority_max = 2; 1791 G1ParGCAllocBuffer* _priority_buffer[_priority_max]; 1792 1793 public: 1794 G1ParGCAllocBufferContainer(size_t gclab_word_size) { 1795 for (int pr = 0; pr < _priority_max; ++pr) { 1796 _priority_buffer[pr] = new G1ParGCAllocBuffer(gclab_word_size); 1797 } 1798 } 1799 1800 ~G1ParGCAllocBufferContainer() { 1801 for (int pr = 0; pr < _priority_max; ++pr) { 1802 assert(_priority_buffer[pr]->is_retired(), "alloc buffers should all retire at this point."); 1803 delete _priority_buffer[pr]; 1804 } 1805 } 1806 1807 HeapWord* allocate(size_t word_sz) { 1808 HeapWord* obj; 1809 for (int pr = 0; pr < _priority_max; ++pr) { 1810 obj = _priority_buffer[pr]->allocate(word_sz); 1811 if (obj != NULL) return obj; 1812 } 1813 return obj; 1814 } 1815 1816 bool contains(void* addr) { 1817 for (int pr = 0; pr < _priority_max; ++pr) { 1818 if (_priority_buffer[pr]->contains(addr)) return true; 1819 } 1820 return false; 1821 } 1822 1823 void undo_allocation(HeapWord* obj, size_t word_sz) { 1824 bool finish_undo; 1825 for (int pr = 0; pr < _priority_max; ++pr) { 1826 if (_priority_buffer[pr]->contains(obj)) { 1827 _priority_buffer[pr]->undo_allocation(obj, word_sz); 1828 finish_undo = true; 1829 } 1830 } 1831 if (!finish_undo) ShouldNotReachHere(); 1832 } 1833 1834 size_t words_remaining() { 1835 size_t result = 0; 1836 for (int pr = 0; pr < _priority_max; ++pr) { 1837 result += _priority_buffer[pr]->words_remaining(); 1838 } 1839 return result; 1840 } 1841 1842 size_t words_remaining_in_retired_buffer() { 1843 G1ParGCAllocBuffer* retired = _priority_buffer[0]; 1844 return retired->words_remaining(); 1845 } 1846 1847 void flush_stats_and_retire(PLABStats* stats, bool end_of_gc, bool retain) { 1848 for (int pr = 0; pr < _priority_max; ++pr) { 1849 _priority_buffer[pr]->flush_stats_and_retire(stats, end_of_gc, retain); 1850 } 1851 } 1852 1853 void update(bool end_of_gc, bool retain, HeapWord* buf, size_t word_sz) { 1854 G1ParGCAllocBuffer* retired_and_set = _priority_buffer[0]; 1855 retired_and_set->retire(end_of_gc, retain); 1856 retired_and_set->set_buf(buf); 1857 retired_and_set->set_word_size(word_sz); 1858 adjust_priority_order(); 1859 } 1860 1861 private: 1862 void adjust_priority_order() { 1863 G1ParGCAllocBuffer* retired_and_set = _priority_buffer[0]; 1864 1865 int last = _priority_max - 1; 1866 for (int pr = 0; pr < last; ++pr) { 1867 _priority_buffer[pr] = _priority_buffer[pr + 1]; 1868 } 1869 _priority_buffer[last] = retired_and_set; 1870 } 1871 }; 1872 1873 class G1ParScanThreadState : public StackObj { 1874 protected: 1875 G1CollectedHeap* _g1h; 1876 RefToScanQueue* _refs; 1877 DirtyCardQueue _dcq; 1878 CardTableModRefBS* _ct_bs; 1879 G1RemSet* _g1_rem; 1880 1881 G1ParGCAllocBufferContainer _surviving_alloc_buffer; 1882 G1ParGCAllocBufferContainer _tenured_alloc_buffer; 1883 G1ParGCAllocBufferContainer* _alloc_buffers[GCAllocPurposeCount]; 1884 ageTable _age_table; 1885 1886 size_t _alloc_buffer_waste; 1887 size_t _undo_waste; 1888 1889 OopsInHeapRegionClosure* _evac_failure_cl; 1890 G1ParScanHeapEvacClosure* _evac_cl; 1891 G1ParScanPartialArrayClosure* _partial_scan_cl; 1892 1893 int _hash_seed; 1894 uint _queue_num; 1895 1896 size_t _term_attempts; 1897 1898 double _start; 1899 double _start_strong_roots; 1900 double _strong_roots_time; 1901 double _start_term; 1902 double _term_time; 1903 1904 // Map from young-age-index (0 == not young, 1 is youngest) to 1905 // surviving words. base is what we get back from the malloc call 1906 size_t* _surviving_young_words_base; 1907 // this points into the array, as we use the first few entries for padding 1908 size_t* _surviving_young_words; 1909 1910 #define PADDING_ELEM_NUM (DEFAULT_CACHE_LINE_SIZE / sizeof(size_t)) 1911 1912 void add_to_alloc_buffer_waste(size_t waste) { _alloc_buffer_waste += waste; } 1913 1914 void add_to_undo_waste(size_t waste) { _undo_waste += waste; } 1915 1916 DirtyCardQueue& dirty_card_queue() { return _dcq; } 1917 CardTableModRefBS* ctbs() { return _ct_bs; } 1918 1919 template <class T> void immediate_rs_update(HeapRegion* from, T* p, int tid) { 1920 if (!from->is_survivor()) { 1921 _g1_rem->par_write_ref(from, p, tid); 1922 } 1923 } 1924 1925 template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) { 1926 // If the new value of the field points to the same region or 1927 // is the to-space, we don't need to include it in the Rset updates. 1928 if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) { 1929 size_t card_index = ctbs()->index_for(p); 1930 // If the card hasn't been added to the buffer, do it. 1931 if (ctbs()->mark_card_deferred(card_index)) { 1932 dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index)); 1933 } 1934 } 1935 } 1936 1937 public: 1938 G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num); 1939 1940 ~G1ParScanThreadState() { 1941 FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base, mtGC); 1942 } 1943 1944 RefToScanQueue* refs() { return _refs; } 1945 ageTable* age_table() { return &_age_table; } 1946 1947 G1ParGCAllocBufferContainer* alloc_buffer(GCAllocPurpose purpose) { 1948 return _alloc_buffers[purpose]; 1949 } 1950 1951 size_t alloc_buffer_waste() const { return _alloc_buffer_waste; } 1952 size_t undo_waste() const { return _undo_waste; } 1953 1954 #ifdef ASSERT 1955 bool verify_ref(narrowOop* ref) const; 1956 bool verify_ref(oop* ref) const; 1957 bool verify_task(StarTask ref) const; 1958 #endif // ASSERT 1959 1960 template <class T> void push_on_queue(T* ref) { 1961 assert(verify_ref(ref), "sanity"); 1962 refs()->push(ref); 1963 } 1964 1965 template <class T> void update_rs(HeapRegion* from, T* p, int tid) { 1966 if (G1DeferredRSUpdate) { 1967 deferred_rs_update(from, p, tid); 1968 } else { 1969 immediate_rs_update(from, p, tid); 1970 } 1971 } 1972 1973 HeapWord* allocate_slow(GCAllocPurpose purpose, size_t word_sz) { 1974 HeapWord* obj = NULL; 1975 size_t gclab_word_size = _g1h->desired_plab_sz(purpose); 1976 if (word_sz * 100 < gclab_word_size * ParallelGCBufferWastePct) { 1977 G1ParGCAllocBufferContainer* alloc_buf = alloc_buffer(purpose); 1978 1979 HeapWord* buf = _g1h->par_allocate_during_gc(purpose, gclab_word_size); 1980 if (buf == NULL) return NULL; // Let caller handle allocation failure. 1981 1982 add_to_alloc_buffer_waste(alloc_buf->words_remaining_in_retired_buffer()); 1983 alloc_buf->update(false /* end_of_gc */, false /* retain */, buf, gclab_word_size); 1984 1985 obj = alloc_buf->allocate(word_sz); 1986 assert(obj != NULL, "buffer was definitely big enough..."); 1987 } else { 1988 obj = _g1h->par_allocate_during_gc(purpose, word_sz); 1989 } 1990 return obj; 1991 } 1992 1993 HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz) { 1994 HeapWord* obj = alloc_buffer(purpose)->allocate(word_sz); 1995 if (obj != NULL) return obj; 1996 return allocate_slow(purpose, word_sz); 1997 } 1998 1999 void undo_allocation(GCAllocPurpose purpose, HeapWord* obj, size_t word_sz) { 2000 if (alloc_buffer(purpose)->contains(obj)) { 2001 assert(alloc_buffer(purpose)->contains(obj + word_sz - 1), 2002 "should contain whole object"); 2003 alloc_buffer(purpose)->undo_allocation(obj, word_sz); 2004 } else { 2005 CollectedHeap::fill_with_object(obj, word_sz); 2006 add_to_undo_waste(word_sz); 2007 } 2008 } 2009 2010 void set_evac_failure_closure(OopsInHeapRegionClosure* evac_failure_cl) { 2011 _evac_failure_cl = evac_failure_cl; 2012 } 2013 OopsInHeapRegionClosure* evac_failure_closure() { 2014 return _evac_failure_cl; 2015 } 2016 2017 void set_evac_closure(G1ParScanHeapEvacClosure* evac_cl) { 2018 _evac_cl = evac_cl; 2019 } 2020 2021 void set_partial_scan_closure(G1ParScanPartialArrayClosure* partial_scan_cl) { 2022 _partial_scan_cl = partial_scan_cl; 2023 } 2024 2025 int* hash_seed() { return &_hash_seed; } 2026 uint queue_num() { return _queue_num; } 2027 2028 size_t term_attempts() const { return _term_attempts; } 2029 void note_term_attempt() { _term_attempts++; } 2030 2031 void start_strong_roots() { 2032 _start_strong_roots = os::elapsedTime(); 2033 } 2034 void end_strong_roots() { 2035 _strong_roots_time += (os::elapsedTime() - _start_strong_roots); 2036 } 2037 double strong_roots_time() const { return _strong_roots_time; } 2038 2039 void start_term_time() { 2040 note_term_attempt(); 2041 _start_term = os::elapsedTime(); 2042 } 2043 void end_term_time() { 2044 _term_time += (os::elapsedTime() - _start_term); 2045 } 2046 double term_time() const { return _term_time; } 2047 2048 double elapsed_time() const { 2049 return os::elapsedTime() - _start; 2050 } 2051 2052 static void 2053 print_termination_stats_hdr(outputStream* const st = gclog_or_tty); 2054 void 2055 print_termination_stats(int i, outputStream* const st = gclog_or_tty) const; 2056 2057 size_t* surviving_young_words() { 2058 // We add on to hide entry 0 which accumulates surviving words for 2059 // age -1 regions (i.e. non-young ones) 2060 return _surviving_young_words; 2061 } 2062 2063 void retire_alloc_buffers() { 2064 for (int ap = 0; ap < GCAllocPurposeCount; ++ap) { 2065 size_t waste = _alloc_buffers[ap]->words_remaining(); 2066 add_to_alloc_buffer_waste(waste); 2067 _alloc_buffers[ap]->flush_stats_and_retire(_g1h->stats_for_purpose((GCAllocPurpose)ap), 2068 true /* end_of_gc */, 2069 false /* retain */); 2070 } 2071 } 2072 2073 template <class T> void deal_with_reference(T* ref_to_scan) { 2074 if (has_partial_array_mask(ref_to_scan)) { 2075 _partial_scan_cl->do_oop_nv(ref_to_scan); 2076 } else { 2077 // Note: we can use "raw" versions of "region_containing" because 2078 // "obj_to_scan" is definitely in the heap, and is not in a 2079 // humongous region. 2080 HeapRegion* r = _g1h->heap_region_containing_raw(ref_to_scan); 2081 _evac_cl->set_region(r); 2082 _evac_cl->do_oop_nv(ref_to_scan); 2083 } 2084 } 2085 2086 void deal_with_reference(StarTask ref) { 2087 assert(verify_task(ref), "sanity"); 2088 if (ref.is_narrow()) { 2089 deal_with_reference((narrowOop*)ref); 2090 } else { 2091 deal_with_reference((oop*)ref); 2092 } 2093 } 2094 2095 void trim_queue(); 2096 }; 2097 2098 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1COLLECTEDHEAP_HPP