1 /* 2 * Copyright (c) 2001, 2015, 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_G1_G1COLLECTEDHEAP_HPP 26 #define SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP 27 28 #include "gc/g1/concurrentMark.hpp" 29 #include "gc/g1/evacuationInfo.hpp" 30 #include "gc/g1/g1AllocationContext.hpp" 31 #include "gc/g1/g1BiasedArray.hpp" 32 #include "gc/g1/g1CollectorState.hpp" 33 #include "gc/g1/g1HRPrinter.hpp" 34 #include "gc/g1/g1InCSetState.hpp" 35 #include "gc/g1/g1MonitoringSupport.hpp" 36 #include "gc/g1/g1EvacStats.hpp" 37 #include "gc/g1/g1SATBCardTableModRefBS.hpp" 38 #include "gc/g1/g1YCTypes.hpp" 39 #include "gc/g1/hSpaceCounters.hpp" 40 #include "gc/g1/heapRegionManager.hpp" 41 #include "gc/g1/heapRegionSet.hpp" 42 #include "gc/g1/youngList.hpp" 43 #include "gc/shared/barrierSet.hpp" 44 #include "gc/shared/collectedHeap.hpp" 45 #include "gc/shared/plab.hpp" 46 #include "memory/memRegion.hpp" 47 #include "utilities/stack.hpp" 48 49 // A "G1CollectedHeap" is an implementation of a java heap for HotSpot. 50 // It uses the "Garbage First" heap organization and algorithm, which 51 // may combine concurrent marking with parallel, incremental compaction of 52 // heap subsets that will yield large amounts of garbage. 53 54 // Forward declarations 55 class HeapRegion; 56 class HRRSCleanupTask; 57 class GenerationSpec; 58 class OopsInHeapRegionClosure; 59 class G1ParScanThreadState; 60 class G1ParScanThreadStateSet; 61 class G1KlassScanClosure; 62 class G1ParScanThreadState; 63 class ObjectClosure; 64 class SpaceClosure; 65 class CompactibleSpaceClosure; 66 class Space; 67 class G1CollectorPolicy; 68 class G1RemSet; 69 class HeapRegionRemSetIterator; 70 class ConcurrentMark; 71 class ConcurrentMarkThread; 72 class ConcurrentG1Refine; 73 class ConcurrentGCTimer; 74 class GenerationCounters; 75 class STWGCTimer; 76 class G1NewTracer; 77 class G1OldTracer; 78 class EvacuationFailedInfo; 79 class nmethod; 80 class Ticks; 81 class WorkGang; 82 class G1Allocator; 83 class G1ArchiveAllocator; 84 85 typedef OverflowTaskQueue<StarTask, mtGC> RefToScanQueue; 86 typedef GenericTaskQueueSet<RefToScanQueue, mtGC> RefToScanQueueSet; 87 88 typedef int RegionIdx_t; // needs to hold [ 0..max_regions() ) 89 typedef int CardIdx_t; // needs to hold [ 0..CardsPerRegion ) 90 91 // The G1 STW is alive closure. 92 // An instance is embedded into the G1CH and used as the 93 // (optional) _is_alive_non_header closure in the STW 94 // reference processor. It is also extensively used during 95 // reference processing during STW evacuation pauses. 96 class G1STWIsAliveClosure: public BoolObjectClosure { 97 G1CollectedHeap* _g1; 98 public: 99 G1STWIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) {} 100 bool do_object_b(oop p); 101 }; 102 103 class RefineCardTableEntryClosure; 104 105 class G1RegionMappingChangedListener : public G1MappingChangedListener { 106 private: 107 void reset_from_card_cache(uint start_idx, size_t num_regions); 108 public: 109 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 110 }; 111 112 class G1CollectedHeap : public CollectedHeap { 113 friend class VM_CollectForMetadataAllocation; 114 friend class VM_G1CollectForAllocation; 115 friend class VM_G1CollectFull; 116 friend class VM_G1IncCollectionPause; 117 friend class VMStructs; 118 friend class MutatorAllocRegion; 119 friend class G1GCAllocRegion; 120 121 // Closures used in implementation. 122 friend class G1ParScanThreadState; 123 friend class G1ParScanThreadStateSet; 124 friend class G1ParTask; 125 friend class G1PLABAllocator; 126 friend class G1PrepareCompactClosure; 127 128 // Other related classes. 129 friend class HeapRegionClaimer; 130 131 // Testing classes. 132 friend class G1CheckCSetFastTableClosure; 133 134 private: 135 WorkGang* _workers; 136 137 static size_t _humongous_object_threshold_in_words; 138 139 // The secondary free list which contains regions that have been 140 // freed up during the cleanup process. This will be appended to 141 // the master free list when appropriate. 142 FreeRegionList _secondary_free_list; 143 144 // It keeps track of the old regions. 145 HeapRegionSet _old_set; 146 147 // It keeps track of the humongous regions. 148 HeapRegionSet _humongous_set; 149 150 void eagerly_reclaim_humongous_regions(); 151 152 // The number of regions we could create by expansion. 153 uint _expansion_regions; 154 155 // The block offset table for the G1 heap. 156 G1BlockOffsetSharedArray* _bot_shared; 157 158 // Tears down the region sets / lists so that they are empty and the 159 // regions on the heap do not belong to a region set / list. The 160 // only exception is the humongous set which we leave unaltered. If 161 // free_list_only is true, it will only tear down the master free 162 // list. It is called before a Full GC (free_list_only == false) or 163 // before heap shrinking (free_list_only == true). 164 void tear_down_region_sets(bool free_list_only); 165 166 // Rebuilds the region sets / lists so that they are repopulated to 167 // reflect the contents of the heap. The only exception is the 168 // humongous set which was not torn down in the first place. If 169 // free_list_only is true, it will only rebuild the master free 170 // list. It is called after a Full GC (free_list_only == false) or 171 // after heap shrinking (free_list_only == true). 172 void rebuild_region_sets(bool free_list_only); 173 174 // Callback for region mapping changed events. 175 G1RegionMappingChangedListener _listener; 176 177 // The sequence of all heap regions in the heap. 178 HeapRegionManager _hrm; 179 180 // Manages all allocations with regions except humongous object allocations. 181 G1Allocator* _allocator; 182 183 // Outside of GC pauses, the number of bytes used in all regions other 184 // than the current allocation region(s). 185 size_t _summary_bytes_used; 186 187 void increase_used(size_t bytes); 188 void decrease_used(size_t bytes); 189 190 void set_used(size_t bytes); 191 192 // Class that handles archive allocation ranges. 193 G1ArchiveAllocator* _archive_allocator; 194 195 // Statistics for each allocation context 196 AllocationContextStats _allocation_context_stats; 197 198 // GC allocation statistics policy for survivors. 199 G1EvacStats _survivor_evac_stats; 200 201 // GC allocation statistics policy for tenured objects. 202 G1EvacStats _old_evac_stats; 203 204 // It specifies whether we should attempt to expand the heap after a 205 // region allocation failure. If heap expansion fails we set this to 206 // false so that we don't re-attempt the heap expansion (it's likely 207 // that subsequent expansion attempts will also fail if one fails). 208 // Currently, it is only consulted during GC and it's reset at the 209 // start of each GC. 210 bool _expand_heap_after_alloc_failure; 211 212 // Helper for monitoring and management support. 213 G1MonitoringSupport* _g1mm; 214 215 // Records whether the region at the given index is (still) a 216 // candidate for eager reclaim. Only valid for humongous start 217 // regions; other regions have unspecified values. Humongous start 218 // regions are initialized at start of collection pause, with 219 // candidates removed from the set as they are found reachable from 220 // roots or the young generation. 221 class HumongousReclaimCandidates : public G1BiasedMappedArray<bool> { 222 protected: 223 bool default_value() const { return false; } 224 public: 225 void clear() { G1BiasedMappedArray<bool>::clear(); } 226 void set_candidate(uint region, bool value) { 227 set_by_index(region, value); 228 } 229 bool is_candidate(uint region) { 230 return get_by_index(region); 231 } 232 }; 233 234 HumongousReclaimCandidates _humongous_reclaim_candidates; 235 // Stores whether during humongous object registration we found candidate regions. 236 // If not, we can skip a few steps. 237 bool _has_humongous_reclaim_candidates; 238 239 volatile unsigned _gc_time_stamp; 240 241 G1HRPrinter _hr_printer; 242 243 // It decides whether an explicit GC should start a concurrent cycle 244 // instead of doing a STW GC. Currently, a concurrent cycle is 245 // explicitly started if: 246 // (a) cause == _gc_locker and +GCLockerInvokesConcurrent, or 247 // (b) cause == _g1_humongous_allocation 248 // These are defined in user_requested_concurrent_full_gc() because 249 // these sometimes need to be treated differently: 250 // (c) cause == _java_lang_system_gc and +ExplicitGCInvokesConcurrent. 251 // (d) cause == _dcmd_gc_run and +ExplicitGCInvokesConcurrent. 252 // (e) cause == _update_allocation_context_stats_inc 253 // (f) cause == _wb_conc_mark 254 bool should_do_concurrent_full_gc(GCCause::Cause cause); 255 256 // indicates whether we are in young or mixed GC mode 257 G1CollectorState _collector_state; 258 259 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 260 // concurrent cycles) we have started. 261 volatile uint _old_marking_cycles_started; 262 263 // Keeps track of how many "old marking cycles" (i.e., Full GCs or 264 // concurrent cycles) we have completed. 265 volatile uint _old_marking_cycles_completed; 266 267 bool _heap_summary_sent; 268 269 // This is a non-product method that is helpful for testing. It is 270 // called at the end of a GC and artificially expands the heap by 271 // allocating a number of dead regions. This way we can induce very 272 // frequent marking cycles and stress the cleanup / concurrent 273 // cleanup code more (as all the regions that will be allocated by 274 // this method will be found dead by the marking cycle). 275 void allocate_dummy_regions() PRODUCT_RETURN; 276 277 // Clear RSets after a compaction. It also resets the GC time stamps. 278 void clear_rsets_post_compaction(); 279 280 // If the HR printer is active, dump the state of the regions in the 281 // heap after a compaction. 282 void print_hrm_post_compaction(); 283 284 // Create a memory mapper for auxiliary data structures of the given size and 285 // translation factor. 286 static G1RegionToSpaceMapper* create_aux_memory_mapper(const char* description, 287 size_t size, 288 size_t translation_factor); 289 290 double verify(bool guard, const char* msg); 291 void verify_before_gc(); 292 void verify_after_gc(); 293 294 void log_gc_header(); 295 void log_gc_footer(double pause_time_sec); 296 297 void trace_heap(GCWhen::Type when, const GCTracer* tracer); 298 299 // These are macros so that, if the assert fires, we get the correct 300 // line number, file, etc. 301 302 #define heap_locking_asserts_params(_extra_message_) \ 303 "%s : Heap_lock locked: %s, at safepoint: %s, is VM thread: %s", \ 304 (_extra_message_), \ 305 BOOL_TO_STR(Heap_lock->owned_by_self()), \ 306 BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()), \ 307 BOOL_TO_STR(Thread::current()->is_VM_thread()) 308 309 #define assert_heap_locked() \ 310 do { \ 311 assert(Heap_lock->owned_by_self(), \ 312 heap_locking_asserts_params("should be holding the Heap_lock")); \ 313 } while (0) 314 315 #define assert_heap_locked_or_at_safepoint(_should_be_vm_thread_) \ 316 do { \ 317 assert(Heap_lock->owned_by_self() || \ 318 (SafepointSynchronize::is_at_safepoint() && \ 319 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread())), \ 320 heap_locking_asserts_params("should be holding the Heap_lock or " \ 321 "should be at a safepoint")); \ 322 } while (0) 323 324 #define assert_heap_locked_and_not_at_safepoint() \ 325 do { \ 326 assert(Heap_lock->owned_by_self() && \ 327 !SafepointSynchronize::is_at_safepoint(), \ 328 heap_locking_asserts_params("should be holding the Heap_lock and " \ 329 "should not be at a safepoint")); \ 330 } while (0) 331 332 #define assert_heap_not_locked() \ 333 do { \ 334 assert(!Heap_lock->owned_by_self(), \ 335 heap_locking_asserts_params("should not be holding the Heap_lock")); \ 336 } while (0) 337 338 #define assert_heap_not_locked_and_not_at_safepoint() \ 339 do { \ 340 assert(!Heap_lock->owned_by_self() && \ 341 !SafepointSynchronize::is_at_safepoint(), \ 342 heap_locking_asserts_params("should not be holding the Heap_lock and " \ 343 "should not be at a safepoint")); \ 344 } while (0) 345 346 #define assert_at_safepoint(_should_be_vm_thread_) \ 347 do { \ 348 assert(SafepointSynchronize::is_at_safepoint() && \ 349 ((_should_be_vm_thread_) == Thread::current()->is_VM_thread()), \ 350 heap_locking_asserts_params("should be at a safepoint")); \ 351 } while (0) 352 353 #define assert_not_at_safepoint() \ 354 do { \ 355 assert(!SafepointSynchronize::is_at_safepoint(), \ 356 heap_locking_asserts_params("should not be at a safepoint")); \ 357 } while (0) 358 359 protected: 360 361 // The young region list. 362 YoungList* _young_list; 363 364 // The current policy object for the collector. 365 G1CollectorPolicy* _g1_policy; 366 367 // This is the second level of trying to allocate a new region. If 368 // new_region() didn't find a region on the free_list, this call will 369 // check whether there's anything available on the 370 // secondary_free_list and/or wait for more regions to appear on 371 // that list, if _free_regions_coming is set. 372 HeapRegion* new_region_try_secondary_free_list(bool is_old); 373 374 // Try to allocate a single non-humongous HeapRegion sufficient for 375 // an allocation of the given word_size. If do_expand is true, 376 // attempt to expand the heap if necessary to satisfy the allocation 377 // request. If the region is to be used as an old region or for a 378 // humongous object, set is_old to true. If not, to false. 379 HeapRegion* new_region(size_t word_size, bool is_old, bool do_expand); 380 381 // Initialize a contiguous set of free regions of length num_regions 382 // and starting at index first so that they appear as a single 383 // humongous region. 384 HeapWord* humongous_obj_allocate_initialize_regions(uint first, 385 uint num_regions, 386 size_t word_size, 387 AllocationContext_t context); 388 389 // Attempt to allocate a humongous object of the given size. Return 390 // NULL if unsuccessful. 391 HeapWord* humongous_obj_allocate(size_t word_size, AllocationContext_t context); 392 393 // The following two methods, allocate_new_tlab() and 394 // mem_allocate(), are the two main entry points from the runtime 395 // into the G1's allocation routines. They have the following 396 // assumptions: 397 // 398 // * They should both be called outside safepoints. 399 // 400 // * They should both be called without holding the Heap_lock. 401 // 402 // * All allocation requests for new TLABs should go to 403 // allocate_new_tlab(). 404 // 405 // * All non-TLAB allocation requests should go to mem_allocate(). 406 // 407 // * If either call cannot satisfy the allocation request using the 408 // current allocating region, they will try to get a new one. If 409 // this fails, they will attempt to do an evacuation pause and 410 // retry the allocation. 411 // 412 // * If all allocation attempts fail, even after trying to schedule 413 // an evacuation pause, allocate_new_tlab() will return NULL, 414 // whereas mem_allocate() will attempt a heap expansion and/or 415 // schedule a Full GC. 416 // 417 // * We do not allow humongous-sized TLABs. So, allocate_new_tlab 418 // should never be called with word_size being humongous. All 419 // humongous allocation requests should go to mem_allocate() which 420 // will satisfy them with a special path. 421 422 virtual HeapWord* allocate_new_tlab(size_t word_size); 423 424 virtual HeapWord* mem_allocate(size_t word_size, 425 bool* gc_overhead_limit_was_exceeded); 426 427 // The following three methods take a gc_count_before_ret 428 // parameter which is used to return the GC count if the method 429 // returns NULL. Given that we are required to read the GC count 430 // while holding the Heap_lock, and these paths will take the 431 // Heap_lock at some point, it's easier to get them to read the GC 432 // count while holding the Heap_lock before they return NULL instead 433 // of the caller (namely: mem_allocate()) having to also take the 434 // Heap_lock just to read the GC count. 435 436 // First-level mutator allocation attempt: try to allocate out of 437 // the mutator alloc region without taking the Heap_lock. This 438 // should only be used for non-humongous allocations. 439 inline HeapWord* attempt_allocation(size_t word_size, 440 uint* gc_count_before_ret, 441 uint* gclocker_retry_count_ret); 442 443 // Second-level mutator allocation attempt: take the Heap_lock and 444 // retry the allocation attempt, potentially scheduling a GC 445 // pause. This should only be used for non-humongous allocations. 446 HeapWord* attempt_allocation_slow(size_t word_size, 447 AllocationContext_t context, 448 uint* gc_count_before_ret, 449 uint* gclocker_retry_count_ret); 450 451 // Takes the Heap_lock and attempts a humongous allocation. It can 452 // potentially schedule a GC pause. 453 HeapWord* attempt_allocation_humongous(size_t word_size, 454 uint* gc_count_before_ret, 455 uint* gclocker_retry_count_ret); 456 457 // Allocation attempt that should be called during safepoints (e.g., 458 // at the end of a successful GC). expect_null_mutator_alloc_region 459 // specifies whether the mutator alloc region is expected to be NULL 460 // or not. 461 HeapWord* attempt_allocation_at_safepoint(size_t word_size, 462 AllocationContext_t context, 463 bool expect_null_mutator_alloc_region); 464 465 // These methods are the "callbacks" from the G1AllocRegion class. 466 467 // For mutator alloc regions. 468 HeapRegion* new_mutator_alloc_region(size_t word_size, bool force); 469 void retire_mutator_alloc_region(HeapRegion* alloc_region, 470 size_t allocated_bytes); 471 472 // For GC alloc regions. 473 HeapRegion* new_gc_alloc_region(size_t word_size, uint count, 474 InCSetState dest); 475 void retire_gc_alloc_region(HeapRegion* alloc_region, 476 size_t allocated_bytes, InCSetState dest); 477 478 // - if explicit_gc is true, the GC is for a System.gc() or a heap 479 // inspection request and should collect the entire heap 480 // - if clear_all_soft_refs is true, all soft references should be 481 // cleared during the GC 482 // - if explicit_gc is false, word_size describes the allocation that 483 // the GC should attempt (at least) to satisfy 484 // - it returns false if it is unable to do the collection due to the 485 // GC locker being active, true otherwise 486 bool do_collection(bool explicit_gc, 487 bool clear_all_soft_refs, 488 size_t word_size); 489 490 // Callback from VM_G1CollectFull operation. 491 // Perform a full collection. 492 virtual void do_full_collection(bool clear_all_soft_refs); 493 494 // Resize the heap if necessary after a full collection. If this is 495 // after a collect-for allocation, "word_size" is the allocation size, 496 // and will be considered part of the used portion of the heap. 497 void resize_if_necessary_after_full_collection(size_t word_size); 498 499 // Callback from VM_G1CollectForAllocation operation. 500 // This function does everything necessary/possible to satisfy a 501 // failed allocation request (including collection, expansion, etc.) 502 HeapWord* satisfy_failed_allocation(size_t word_size, 503 AllocationContext_t context, 504 bool* succeeded); 505 private: 506 // Helper method for satisfy_failed_allocation() 507 HeapWord* satisfy_failed_allocation_helper(size_t word_size, 508 AllocationContext_t context, 509 bool do_gc, 510 bool clear_all_soft_refs, 511 bool expect_null_mutator_alloc_region, 512 bool* gc_succeeded); 513 514 protected: 515 // Attempting to expand the heap sufficiently 516 // to support an allocation of the given "word_size". If 517 // successful, perform the allocation and return the address of the 518 // allocated block, or else "NULL". 519 HeapWord* expand_and_allocate(size_t word_size, AllocationContext_t context); 520 521 // Process any reference objects discovered during 522 // an incremental evacuation pause. 523 void process_discovered_references(G1ParScanThreadStateSet* per_thread_states); 524 525 // Enqueue any remaining discovered references 526 // after processing. 527 void enqueue_discovered_references(G1ParScanThreadStateSet* per_thread_states); 528 529 public: 530 WorkGang* workers() const { return _workers; } 531 532 G1Allocator* allocator() { 533 return _allocator; 534 } 535 536 G1MonitoringSupport* g1mm() { 537 assert(_g1mm != NULL, "should have been initialized"); 538 return _g1mm; 539 } 540 541 // Expand the garbage-first heap by at least the given size (in bytes!). 542 // Returns true if the heap was expanded by the requested amount; 543 // false otherwise. 544 // (Rounds up to a HeapRegion boundary.) 545 bool expand(size_t expand_bytes, double* expand_time_ms = NULL); 546 547 // Returns the PLAB statistics for a given destination. 548 inline G1EvacStats* alloc_buffer_stats(InCSetState dest); 549 550 // Determines PLAB size for a given destination. 551 inline size_t desired_plab_sz(InCSetState dest); 552 553 inline AllocationContextStats& allocation_context_stats(); 554 555 // Do anything common to GC's. 556 void gc_prologue(bool full); 557 void gc_epilogue(bool full); 558 559 // Modify the reclaim candidate set and test for presence. 560 // These are only valid for starts_humongous regions. 561 inline void set_humongous_reclaim_candidate(uint region, bool value); 562 inline bool is_humongous_reclaim_candidate(uint region); 563 564 // Remove from the reclaim candidate set. Also remove from the 565 // collection set so that later encounters avoid the slow path. 566 inline void set_humongous_is_live(oop obj); 567 568 // Register the given region to be part of the collection set. 569 inline void register_humongous_region_with_cset(uint index); 570 // Register regions with humongous objects (actually on the start region) in 571 // the in_cset_fast_test table. 572 void register_humongous_regions_with_cset(); 573 // We register a region with the fast "in collection set" test. We 574 // simply set to true the array slot corresponding to this region. 575 void register_young_region_with_cset(HeapRegion* r) { 576 _in_cset_fast_test.set_in_young(r->hrm_index()); 577 } 578 void register_old_region_with_cset(HeapRegion* r) { 579 _in_cset_fast_test.set_in_old(r->hrm_index()); 580 } 581 void clear_in_cset(const HeapRegion* hr) { 582 _in_cset_fast_test.clear(hr); 583 } 584 585 void clear_cset_fast_test() { 586 _in_cset_fast_test.clear(); 587 } 588 589 // A complement to should_do_concurrent_full_gc. GCs caused 590 // by a user sometimes needs to be treated differently 591 // from those caused by the VM. 592 bool user_requested_concurrent_full_gc(GCCause::Cause cause); 593 594 // This is called at the start of either a concurrent cycle or a Full 595 // GC to update the number of old marking cycles started. 596 void increment_old_marking_cycles_started(); 597 598 // This is called at the end of either a concurrent cycle or a Full 599 // GC to update the number of old marking cycles completed. Those two 600 // can happen in a nested fashion, i.e., we start a concurrent 601 // cycle, a Full GC happens half-way through it which ends first, 602 // and then the cycle notices that a Full GC happened and ends 603 // too. The concurrent parameter is a boolean to help us do a bit 604 // tighter consistency checking in the method. If concurrent is 605 // false, the caller is the inner caller in the nesting (i.e., the 606 // Full GC). If concurrent is true, the caller is the outer caller 607 // in this nesting (i.e., the concurrent cycle). Further nesting is 608 // not currently supported. The end of this call also notifies 609 // the FullGCCount_lock in case a Java thread is waiting for a full 610 // GC to happen (e.g., it called System.gc() with 611 // +ExplicitGCInvokesConcurrent). 612 void increment_old_marking_cycles_completed(bool concurrent); 613 614 uint old_marking_cycles_completed() { 615 return _old_marking_cycles_completed; 616 } 617 618 void register_concurrent_cycle_start(const Ticks& start_time); 619 void register_concurrent_cycle_end(); 620 void trace_heap_after_concurrent_cycle(); 621 622 G1HRPrinter* hr_printer() { return &_hr_printer; } 623 624 // Allocates a new heap region instance. 625 HeapRegion* new_heap_region(uint hrs_index, MemRegion mr); 626 627 // Allocate the highest free region in the reserved heap. This will commit 628 // regions as necessary. 629 HeapRegion* alloc_highest_free_region(); 630 631 // Frees a non-humongous region by initializing its contents and 632 // adding it to the free list that's passed as a parameter (this is 633 // usually a local list which will be appended to the master free 634 // list later). The used bytes of freed regions are accumulated in 635 // pre_used. If par is true, the region's RSet will not be freed 636 // up. The assumption is that this will be done later. 637 // The locked parameter indicates if the caller has already taken 638 // care of proper synchronization. This may allow some optimizations. 639 void free_region(HeapRegion* hr, 640 FreeRegionList* free_list, 641 bool par, 642 bool locked = false); 643 644 // It dirties the cards that cover the block so that the post 645 // write barrier never queues anything when updating objects on this 646 // block. It is assumed (and in fact we assert) that the block 647 // belongs to a young region. 648 inline void dirty_young_block(HeapWord* start, size_t word_size); 649 650 // Frees a humongous region by collapsing it into individual regions 651 // and calling free_region() for each of them. The freed regions 652 // will be added to the free list that's passed as a parameter (this 653 // is usually a local list which will be appended to the master free 654 // list later). The used bytes of freed regions are accumulated in 655 // pre_used. If par is true, the region's RSet will not be freed 656 // up. The assumption is that this will be done later. 657 void free_humongous_region(HeapRegion* hr, 658 FreeRegionList* free_list, 659 bool par); 660 661 // Facility for allocating in 'archive' regions in high heap memory and 662 // recording the allocated ranges. These should all be called from the 663 // VM thread at safepoints, without the heap lock held. They can be used 664 // to create and archive a set of heap regions which can be mapped at the 665 // same fixed addresses in a subsequent JVM invocation. 666 void begin_archive_alloc_range(); 667 668 // Check if the requested size would be too large for an archive allocation. 669 bool is_archive_alloc_too_large(size_t word_size); 670 671 // Allocate memory of the requested size from the archive region. This will 672 // return NULL if the size is too large or if no memory is available. It 673 // does not trigger a garbage collection. 674 HeapWord* archive_mem_allocate(size_t word_size); 675 676 // Optionally aligns the end address and returns the allocated ranges in 677 // an array of MemRegions in order of ascending addresses. 678 void end_archive_alloc_range(GrowableArray<MemRegion>* ranges, 679 size_t end_alignment_in_bytes = 0); 680 681 // Facility for allocating a fixed range within the heap and marking 682 // the containing regions as 'archive'. For use at JVM init time, when the 683 // caller may mmap archived heap data at the specified range(s). 684 // Verify that the MemRegions specified in the argument array are within the 685 // reserved heap. 686 bool check_archive_addresses(MemRegion* range, size_t count); 687 688 // Commit the appropriate G1 regions containing the specified MemRegions 689 // and mark them as 'archive' regions. The regions in the array must be 690 // non-overlapping and in order of ascending address. 691 bool alloc_archive_regions(MemRegion* range, size_t count); 692 693 // Insert any required filler objects in the G1 regions around the specified 694 // ranges to make the regions parseable. This must be called after 695 // alloc_archive_regions, and after class loading has occurred. 696 void fill_archive_regions(MemRegion* range, size_t count); 697 698 // For each of the specified MemRegions, uncommit the containing G1 regions 699 // which had been allocated by alloc_archive_regions. This should be called 700 // rather than fill_archive_regions at JVM init time if the archive file 701 // mapping failed, with the same non-overlapping and sorted MemRegion array. 702 void dealloc_archive_regions(MemRegion* range, size_t count); 703 704 protected: 705 706 // Shrink the garbage-first heap by at most the given size (in bytes!). 707 // (Rounds down to a HeapRegion boundary.) 708 virtual void shrink(size_t expand_bytes); 709 void shrink_helper(size_t expand_bytes); 710 711 #if TASKQUEUE_STATS 712 static void print_taskqueue_stats_hdr(outputStream* const st = gclog_or_tty); 713 void print_taskqueue_stats(outputStream* const st = gclog_or_tty) const; 714 void reset_taskqueue_stats(); 715 #endif // TASKQUEUE_STATS 716 717 // Schedule the VM operation that will do an evacuation pause to 718 // satisfy an allocation request of word_size. *succeeded will 719 // return whether the VM operation was successful (it did do an 720 // evacuation pause) or not (another thread beat us to it or the GC 721 // locker was active). Given that we should not be holding the 722 // Heap_lock when we enter this method, we will pass the 723 // gc_count_before (i.e., total_collections()) as a parameter since 724 // it has to be read while holding the Heap_lock. Currently, both 725 // methods that call do_collection_pause() release the Heap_lock 726 // before the call, so it's easy to read gc_count_before just before. 727 HeapWord* do_collection_pause(size_t word_size, 728 uint gc_count_before, 729 bool* succeeded, 730 GCCause::Cause gc_cause); 731 732 void wait_for_root_region_scanning(); 733 734 // The guts of the incremental collection pause, executed by the vm 735 // thread. It returns false if it is unable to do the collection due 736 // to the GC locker being active, true otherwise 737 bool do_collection_pause_at_safepoint(double target_pause_time_ms); 738 739 // Actually do the work of evacuating the collection set. 740 virtual void evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states); 741 742 void pre_evacuate_collection_set(); 743 void post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* pss); 744 745 // Print the header for the per-thread termination statistics. 746 static void print_termination_stats_hdr(outputStream* const st); 747 // Print actual per-thread termination statistics. 748 void print_termination_stats(outputStream* const st, 749 uint worker_id, 750 double elapsed_ms, 751 double strong_roots_ms, 752 double term_ms, 753 size_t term_attempts, 754 size_t alloc_buffer_waste, 755 size_t undo_waste) const; 756 // Update object copying statistics. 757 void record_obj_copy_mem_stats(); 758 759 // The g1 remembered set of the heap. 760 G1RemSet* _g1_rem_set; 761 762 // A set of cards that cover the objects for which the Rsets should be updated 763 // concurrently after the collection. 764 DirtyCardQueueSet _dirty_card_queue_set; 765 766 // The closure used to refine a single card. 767 RefineCardTableEntryClosure* _refine_cte_cl; 768 769 // After a collection pause, make the regions in the CS into free 770 // regions. 771 void free_collection_set(HeapRegion* cs_head, EvacuationInfo& evacuation_info, const size_t* surviving_young_words); 772 773 // Abandon the current collection set without recording policy 774 // statistics or updating free lists. 775 void abandon_collection_set(HeapRegion* cs_head); 776 777 // The concurrent marker (and the thread it runs in.) 778 ConcurrentMark* _cm; 779 ConcurrentMarkThread* _cmThread; 780 781 // The concurrent refiner. 782 ConcurrentG1Refine* _cg1r; 783 784 // The parallel task queues 785 RefToScanQueueSet *_task_queues; 786 787 // True iff a evacuation has failed in the current collection. 788 bool _evacuation_failed; 789 790 EvacuationFailedInfo* _evacuation_failed_info_array; 791 792 // Failed evacuations cause some logical from-space objects to have 793 // forwarding pointers to themselves. Reset them. 794 void remove_self_forwarding_pointers(); 795 796 struct OopAndMarkOop { 797 private: 798 oop _o; 799 markOop _m; 800 public: 801 OopAndMarkOop(oop obj, markOop m) : _o(obj), _m(m) { 802 } 803 804 void set_mark() { 805 _o->set_mark(_m); 806 } 807 }; 808 809 typedef Stack<OopAndMarkOop,mtGC> OopAndMarkOopStack; 810 // Stores marks with the corresponding oop that we need to preserve during evacuation 811 // failure. 812 OopAndMarkOopStack* _preserved_objs; 813 814 // Preserve the mark of "obj", if necessary, in preparation for its mark 815 // word being overwritten with a self-forwarding-pointer. 816 void preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m); 817 818 #ifndef PRODUCT 819 // Support for forcing evacuation failures. Analogous to 820 // PromotionFailureALot for the other collectors. 821 822 // Records whether G1EvacuationFailureALot should be in effect 823 // for the current GC 824 bool _evacuation_failure_alot_for_current_gc; 825 826 // Used to record the GC number for interval checking when 827 // determining whether G1EvaucationFailureALot is in effect 828 // for the current GC. 829 size_t _evacuation_failure_alot_gc_number; 830 831 // Count of the number of evacuations between failures. 832 volatile size_t _evacuation_failure_alot_count; 833 834 // Set whether G1EvacuationFailureALot should be in effect 835 // for the current GC (based upon the type of GC and which 836 // command line flags are set); 837 inline bool evacuation_failure_alot_for_gc_type(bool gcs_are_young, 838 bool during_initial_mark, 839 bool during_marking); 840 841 inline void set_evacuation_failure_alot_for_current_gc(); 842 843 // Return true if it's time to cause an evacuation failure. 844 inline bool evacuation_should_fail(); 845 846 // Reset the G1EvacuationFailureALot counters. Should be called at 847 // the end of an evacuation pause in which an evacuation failure occurred. 848 inline void reset_evacuation_should_fail(); 849 #endif // !PRODUCT 850 851 // ("Weak") Reference processing support. 852 // 853 // G1 has 2 instances of the reference processor class. One 854 // (_ref_processor_cm) handles reference object discovery 855 // and subsequent processing during concurrent marking cycles. 856 // 857 // The other (_ref_processor_stw) handles reference object 858 // discovery and processing during full GCs and incremental 859 // evacuation pauses. 860 // 861 // During an incremental pause, reference discovery will be 862 // temporarily disabled for _ref_processor_cm and will be 863 // enabled for _ref_processor_stw. At the end of the evacuation 864 // pause references discovered by _ref_processor_stw will be 865 // processed and discovery will be disabled. The previous 866 // setting for reference object discovery for _ref_processor_cm 867 // will be re-instated. 868 // 869 // At the start of marking: 870 // * Discovery by the CM ref processor is verified to be inactive 871 // and it's discovered lists are empty. 872 // * Discovery by the CM ref processor is then enabled. 873 // 874 // At the end of marking: 875 // * Any references on the CM ref processor's discovered 876 // lists are processed (possibly MT). 877 // 878 // At the start of full GC we: 879 // * Disable discovery by the CM ref processor and 880 // empty CM ref processor's discovered lists 881 // (without processing any entries). 882 // * Verify that the STW ref processor is inactive and it's 883 // discovered lists are empty. 884 // * Temporarily set STW ref processor discovery as single threaded. 885 // * Temporarily clear the STW ref processor's _is_alive_non_header 886 // field. 887 // * Finally enable discovery by the STW ref processor. 888 // 889 // The STW ref processor is used to record any discovered 890 // references during the full GC. 891 // 892 // At the end of a full GC we: 893 // * Enqueue any reference objects discovered by the STW ref processor 894 // that have non-live referents. This has the side-effect of 895 // making the STW ref processor inactive by disabling discovery. 896 // * Verify that the CM ref processor is still inactive 897 // and no references have been placed on it's discovered 898 // lists (also checked as a precondition during initial marking). 899 900 // The (stw) reference processor... 901 ReferenceProcessor* _ref_processor_stw; 902 903 STWGCTimer* _gc_timer_stw; 904 ConcurrentGCTimer* _gc_timer_cm; 905 906 G1OldTracer* _gc_tracer_cm; 907 G1NewTracer* _gc_tracer_stw; 908 909 // During reference object discovery, the _is_alive_non_header 910 // closure (if non-null) is applied to the referent object to 911 // determine whether the referent is live. If so then the 912 // reference object does not need to be 'discovered' and can 913 // be treated as a regular oop. This has the benefit of reducing 914 // the number of 'discovered' reference objects that need to 915 // be processed. 916 // 917 // Instance of the is_alive closure for embedding into the 918 // STW reference processor as the _is_alive_non_header field. 919 // Supplying a value for the _is_alive_non_header field is 920 // optional but doing so prevents unnecessary additions to 921 // the discovered lists during reference discovery. 922 G1STWIsAliveClosure _is_alive_closure_stw; 923 924 // The (concurrent marking) reference processor... 925 ReferenceProcessor* _ref_processor_cm; 926 927 // Instance of the concurrent mark is_alive closure for embedding 928 // into the Concurrent Marking reference processor as the 929 // _is_alive_non_header field. Supplying a value for the 930 // _is_alive_non_header field is optional but doing so prevents 931 // unnecessary additions to the discovered lists during reference 932 // discovery. 933 G1CMIsAliveClosure _is_alive_closure_cm; 934 935 // Cache used by G1CollectedHeap::start_cset_region_for_worker(). 936 HeapRegion** _worker_cset_start_region; 937 938 // Time stamp to validate the regions recorded in the cache 939 // used by G1CollectedHeap::start_cset_region_for_worker(). 940 // The heap region entry for a given worker is valid iff 941 // the associated time stamp value matches the current value 942 // of G1CollectedHeap::_gc_time_stamp. 943 uint* _worker_cset_start_region_time_stamp; 944 945 volatile bool _free_regions_coming; 946 947 public: 948 949 void set_refine_cte_cl_concurrency(bool concurrent); 950 951 RefToScanQueue *task_queue(uint i) const; 952 953 uint num_task_queues() const; 954 955 // A set of cards where updates happened during the GC 956 DirtyCardQueueSet& dirty_card_queue_set() { return _dirty_card_queue_set; } 957 958 // Create a G1CollectedHeap with the specified policy. 959 // Must call the initialize method afterwards. 960 // May not return if something goes wrong. 961 G1CollectedHeap(G1CollectorPolicy* policy); 962 963 // Initialize the G1CollectedHeap to have the initial and 964 // maximum sizes and remembered and barrier sets 965 // specified by the policy object. 966 jint initialize(); 967 968 virtual void stop(); 969 970 // Return the (conservative) maximum heap alignment for any G1 heap 971 static size_t conservative_max_heap_alignment(); 972 973 // Does operations required after initialization has been done. 974 void post_initialize(); 975 976 // Initialize weak reference processing. 977 void ref_processing_init(); 978 979 virtual Name kind() const { 980 return CollectedHeap::G1CollectedHeap; 981 } 982 983 const G1CollectorState* collector_state() const { return &_collector_state; } 984 G1CollectorState* collector_state() { return &_collector_state; } 985 986 // The current policy object for the collector. 987 G1CollectorPolicy* g1_policy() const { return _g1_policy; } 988 989 virtual CollectorPolicy* collector_policy() const; 990 991 // Adaptive size policy. No such thing for g1. 992 virtual AdaptiveSizePolicy* size_policy() { return NULL; } 993 994 // The rem set and barrier set. 995 G1RemSet* g1_rem_set() const { return _g1_rem_set; } 996 997 unsigned get_gc_time_stamp() { 998 return _gc_time_stamp; 999 } 1000 1001 inline void reset_gc_time_stamp(); 1002 1003 void check_gc_time_stamps() PRODUCT_RETURN; 1004 1005 inline void increment_gc_time_stamp(); 1006 1007 // Reset the given region's GC timestamp. If it's starts humongous, 1008 // also reset the GC timestamp of its corresponding 1009 // continues humongous regions too. 1010 void reset_gc_time_stamps(HeapRegion* hr); 1011 1012 // Apply the given closure on all cards in the Hot Card Cache, emptying it. 1013 void iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i); 1014 1015 // Apply the given closure on all cards in the Dirty Card Queue Set, emptying it. 1016 void iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i); 1017 1018 // The shared block offset table array. 1019 G1BlockOffsetSharedArray* bot_shared() const { return _bot_shared; } 1020 1021 // Reference Processing accessors 1022 1023 // The STW reference processor.... 1024 ReferenceProcessor* ref_processor_stw() const { return _ref_processor_stw; } 1025 1026 G1NewTracer* gc_tracer_stw() const { return _gc_tracer_stw; } 1027 1028 // The Concurrent Marking reference processor... 1029 ReferenceProcessor* ref_processor_cm() const { return _ref_processor_cm; } 1030 1031 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; } 1032 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; } 1033 1034 virtual size_t capacity() const; 1035 virtual size_t used() const; 1036 // This should be called when we're not holding the heap lock. The 1037 // result might be a bit inaccurate. 1038 size_t used_unlocked() const; 1039 size_t recalculate_used() const; 1040 1041 // These virtual functions do the actual allocation. 1042 // Some heaps may offer a contiguous region for shared non-blocking 1043 // allocation, via inlined code (by exporting the address of the top and 1044 // end fields defining the extent of the contiguous allocation region.) 1045 // But G1CollectedHeap doesn't yet support this. 1046 1047 virtual bool is_maximal_no_gc() const { 1048 return _hrm.available() == 0; 1049 } 1050 1051 // The current number of regions in the heap. 1052 uint num_regions() const { return _hrm.length(); } 1053 1054 // The max number of regions in the heap. 1055 uint max_regions() const { return _hrm.max_length(); } 1056 1057 // The number of regions that are completely free. 1058 uint num_free_regions() const { return _hrm.num_free_regions(); } 1059 1060 MemoryUsage get_auxiliary_data_memory_usage() const { 1061 return _hrm.get_auxiliary_data_memory_usage(); 1062 } 1063 1064 // The number of regions that are not completely free. 1065 uint num_used_regions() const { return num_regions() - num_free_regions(); } 1066 1067 void verify_not_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1068 void verify_dirty_region(HeapRegion* hr) PRODUCT_RETURN; 1069 void verify_dirty_young_list(HeapRegion* head) PRODUCT_RETURN; 1070 void verify_dirty_young_regions() PRODUCT_RETURN; 1071 1072 #ifndef PRODUCT 1073 // Make sure that the given bitmap has no marked objects in the 1074 // range [from,limit). If it does, print an error message and return 1075 // false. Otherwise, just return true. bitmap_name should be "prev" 1076 // or "next". 1077 bool verify_no_bits_over_tams(const char* bitmap_name, CMBitMapRO* bitmap, 1078 HeapWord* from, HeapWord* limit); 1079 1080 // Verify that the prev / next bitmap range [tams,end) for the given 1081 // region has no marks. Return true if all is well, false if errors 1082 // are detected. 1083 bool verify_bitmaps(const char* caller, HeapRegion* hr); 1084 #endif // PRODUCT 1085 1086 // If G1VerifyBitmaps is set, verify that the marking bitmaps for 1087 // the given region do not have any spurious marks. If errors are 1088 // detected, print appropriate error messages and crash. 1089 void check_bitmaps(const char* caller, HeapRegion* hr) PRODUCT_RETURN; 1090 1091 // If G1VerifyBitmaps is set, verify that the marking bitmaps do not 1092 // have any spurious marks. If errors are detected, print 1093 // appropriate error messages and crash. 1094 void check_bitmaps(const char* caller) PRODUCT_RETURN; 1095 1096 // Do sanity check on the contents of the in-cset fast test table. 1097 bool check_cset_fast_test() PRODUCT_RETURN_( return true; ); 1098 1099 // verify_region_sets() performs verification over the region 1100 // lists. It will be compiled in the product code to be used when 1101 // necessary (i.e., during heap verification). 1102 void verify_region_sets(); 1103 1104 // verify_region_sets_optional() is planted in the code for 1105 // list verification in non-product builds (and it can be enabled in 1106 // product builds by defining HEAP_REGION_SET_FORCE_VERIFY to be 1). 1107 #if HEAP_REGION_SET_FORCE_VERIFY 1108 void verify_region_sets_optional() { 1109 verify_region_sets(); 1110 } 1111 #else // HEAP_REGION_SET_FORCE_VERIFY 1112 void verify_region_sets_optional() { } 1113 #endif // HEAP_REGION_SET_FORCE_VERIFY 1114 1115 #ifdef ASSERT 1116 bool is_on_master_free_list(HeapRegion* hr) { 1117 return _hrm.is_free(hr); 1118 } 1119 #endif // ASSERT 1120 1121 // Wrapper for the region list operations that can be called from 1122 // methods outside this class. 1123 1124 void secondary_free_list_add(FreeRegionList* list) { 1125 _secondary_free_list.add_ordered(list); 1126 } 1127 1128 void append_secondary_free_list() { 1129 _hrm.insert_list_into_free_list(&_secondary_free_list); 1130 } 1131 1132 void append_secondary_free_list_if_not_empty_with_lock() { 1133 // If the secondary free list looks empty there's no reason to 1134 // take the lock and then try to append it. 1135 if (!_secondary_free_list.is_empty()) { 1136 MutexLockerEx x(SecondaryFreeList_lock, Mutex::_no_safepoint_check_flag); 1137 append_secondary_free_list(); 1138 } 1139 } 1140 1141 inline void old_set_add(HeapRegion* hr); 1142 inline void old_set_remove(HeapRegion* hr); 1143 1144 size_t non_young_capacity_bytes() { 1145 return _old_set.total_capacity_bytes() + _humongous_set.total_capacity_bytes(); 1146 } 1147 1148 void set_free_regions_coming(); 1149 void reset_free_regions_coming(); 1150 bool free_regions_coming() { return _free_regions_coming; } 1151 void wait_while_free_regions_coming(); 1152 1153 // Determine whether the given region is one that we are using as an 1154 // old GC alloc region. 1155 bool is_old_gc_alloc_region(HeapRegion* hr); 1156 1157 // Perform a collection of the heap; intended for use in implementing 1158 // "System.gc". This probably implies as full a collection as the 1159 // "CollectedHeap" supports. 1160 virtual void collect(GCCause::Cause cause); 1161 1162 // The same as above but assume that the caller holds the Heap_lock. 1163 void collect_locked(GCCause::Cause cause); 1164 1165 virtual bool copy_allocation_context_stats(const jint* contexts, 1166 jlong* totals, 1167 jbyte* accuracy, 1168 jint len); 1169 1170 // True iff an evacuation has failed in the most-recent collection. 1171 bool evacuation_failed() { return _evacuation_failed; } 1172 1173 void remove_from_old_sets(const HeapRegionSetCount& old_regions_removed, const HeapRegionSetCount& humongous_regions_removed); 1174 void prepend_to_freelist(FreeRegionList* list); 1175 void decrement_summary_bytes(size_t bytes); 1176 1177 virtual bool is_in(const void* p) const; 1178 #ifdef ASSERT 1179 // Returns whether p is in one of the available areas of the heap. Slow but 1180 // extensive version. 1181 bool is_in_exact(const void* p) const; 1182 #endif 1183 1184 // Return "TRUE" iff the given object address is within the collection 1185 // set. Slow implementation. 1186 bool obj_in_cs(oop obj); 1187 1188 inline bool is_in_cset(const HeapRegion *hr); 1189 inline bool is_in_cset(oop obj); 1190 1191 inline bool is_in_cset_or_humongous(const oop obj); 1192 1193 private: 1194 // This array is used for a quick test on whether a reference points into 1195 // the collection set or not. Each of the array's elements denotes whether the 1196 // corresponding region is in the collection set or not. 1197 G1InCSetStateFastTestBiasedMappedArray _in_cset_fast_test; 1198 1199 public: 1200 1201 inline InCSetState in_cset_state(const oop obj); 1202 1203 // Return "TRUE" iff the given object address is in the reserved 1204 // region of g1. 1205 bool is_in_g1_reserved(const void* p) const { 1206 return _hrm.reserved().contains(p); 1207 } 1208 1209 // Returns a MemRegion that corresponds to the space that has been 1210 // reserved for the heap 1211 MemRegion g1_reserved() const { 1212 return _hrm.reserved(); 1213 } 1214 1215 virtual bool is_in_closed_subset(const void* p) const; 1216 1217 G1SATBCardTableLoggingModRefBS* g1_barrier_set() { 1218 return barrier_set_cast<G1SATBCardTableLoggingModRefBS>(barrier_set()); 1219 } 1220 1221 // This resets the card table to all zeros. It is used after 1222 // a collection pause which used the card table to claim cards. 1223 void cleanUpCardTable(); 1224 1225 // Iteration functions. 1226 1227 // Iterate over all objects, calling "cl.do_object" on each. 1228 virtual void object_iterate(ObjectClosure* cl); 1229 1230 virtual void safe_object_iterate(ObjectClosure* cl) { 1231 object_iterate(cl); 1232 } 1233 1234 // Iterate over heap regions, in address order, terminating the 1235 // iteration early if the "doHeapRegion" method returns "true". 1236 void heap_region_iterate(HeapRegionClosure* blk) const; 1237 1238 // Return the region with the given index. It assumes the index is valid. 1239 inline HeapRegion* region_at(uint index) const; 1240 1241 // Return the next region (by index) that is part of the same 1242 // humongous object that hr is part of. 1243 inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const; 1244 1245 // Calculate the region index of the given address. Given address must be 1246 // within the heap. 1247 inline uint addr_to_region(HeapWord* addr) const; 1248 1249 inline HeapWord* bottom_addr_for_region(uint index) const; 1250 1251 // Iterate over the heap regions in parallel. Assumes that this will be called 1252 // in parallel by ParallelGCThreads worker threads with distinct worker ids 1253 // in the range [0..max(ParallelGCThreads-1, 1)]. Applies "blk->doHeapRegion" 1254 // to each of the regions, by attempting to claim the region using the 1255 // HeapRegionClaimer and, if successful, applying the closure to the claimed 1256 // region. The concurrent argument should be set to true if iteration is 1257 // performed concurrently, during which no assumptions are made for consistent 1258 // attributes of the heap regions (as they might be modified while iterating). 1259 void heap_region_par_iterate(HeapRegionClosure* cl, 1260 uint worker_id, 1261 HeapRegionClaimer* hrclaimer, 1262 bool concurrent = false) const; 1263 1264 // Clear the cached cset start regions and (more importantly) 1265 // the time stamps. Called when we reset the GC time stamp. 1266 void clear_cset_start_regions(); 1267 1268 // Given the id of a worker, obtain or calculate a suitable 1269 // starting region for iterating over the current collection set. 1270 HeapRegion* start_cset_region_for_worker(uint worker_i); 1271 1272 // Iterate over the regions (if any) in the current collection set. 1273 void collection_set_iterate(HeapRegionClosure* blk); 1274 1275 // As above but starting from region r 1276 void collection_set_iterate_from(HeapRegion* r, HeapRegionClosure *blk); 1277 1278 HeapRegion* next_compaction_region(const HeapRegion* from) const; 1279 1280 // Returns the HeapRegion that contains addr. addr must not be NULL. 1281 template <class T> 1282 inline HeapRegion* heap_region_containing(const T addr) const; 1283 1284 // A CollectedHeap is divided into a dense sequence of "blocks"; that is, 1285 // each address in the (reserved) heap is a member of exactly 1286 // one block. The defining characteristic of a block is that it is 1287 // possible to find its size, and thus to progress forward to the next 1288 // block. (Blocks may be of different sizes.) Thus, blocks may 1289 // represent Java objects, or they might be free blocks in a 1290 // free-list-based heap (or subheap), as long as the two kinds are 1291 // distinguishable and the size of each is determinable. 1292 1293 // Returns the address of the start of the "block" that contains the 1294 // address "addr". We say "blocks" instead of "object" since some heaps 1295 // may not pack objects densely; a chunk may either be an object or a 1296 // non-object. 1297 virtual HeapWord* block_start(const void* addr) const; 1298 1299 // Requires "addr" to be the start of a chunk, and returns its size. 1300 // "addr + size" is required to be the start of a new chunk, or the end 1301 // of the active area of the heap. 1302 virtual size_t block_size(const HeapWord* addr) const; 1303 1304 // Requires "addr" to be the start of a block, and returns "TRUE" iff 1305 // the block is an object. 1306 virtual bool block_is_obj(const HeapWord* addr) const; 1307 1308 // Section on thread-local allocation buffers (TLABs) 1309 // See CollectedHeap for semantics. 1310 1311 bool supports_tlab_allocation() const; 1312 size_t tlab_capacity(Thread* ignored) const; 1313 size_t tlab_used(Thread* ignored) const; 1314 size_t max_tlab_size() const; 1315 size_t unsafe_max_tlab_alloc(Thread* ignored) const; 1316 1317 // Can a compiler initialize a new object without store barriers? 1318 // This permission only extends from the creation of a new object 1319 // via a TLAB up to the first subsequent safepoint. If such permission 1320 // is granted for this heap type, the compiler promises to call 1321 // defer_store_barrier() below on any slow path allocation of 1322 // a new object for which such initializing store barriers will 1323 // have been elided. G1, like CMS, allows this, but should be 1324 // ready to provide a compensating write barrier as necessary 1325 // if that storage came out of a non-young region. The efficiency 1326 // of this implementation depends crucially on being able to 1327 // answer very efficiently in constant time whether a piece of 1328 // storage in the heap comes from a young region or not. 1329 // See ReduceInitialCardMarks. 1330 virtual bool can_elide_tlab_store_barriers() const { 1331 return true; 1332 } 1333 1334 virtual bool card_mark_must_follow_store() const { 1335 return true; 1336 } 1337 1338 inline bool is_in_young(const oop obj); 1339 1340 virtual bool is_scavengable(const void* addr); 1341 1342 // We don't need barriers for initializing stores to objects 1343 // in the young gen: for the SATB pre-barrier, there is no 1344 // pre-value that needs to be remembered; for the remembered-set 1345 // update logging post-barrier, we don't maintain remembered set 1346 // information for young gen objects. 1347 virtual inline bool can_elide_initializing_store_barrier(oop new_obj); 1348 1349 // Returns "true" iff the given word_size is "very large". 1350 static bool is_humongous(size_t word_size) { 1351 // Note this has to be strictly greater-than as the TLABs 1352 // are capped at the humongous threshold and we want to 1353 // ensure that we don't try to allocate a TLAB as 1354 // humongous and that we don't allocate a humongous 1355 // object in a TLAB. 1356 return word_size > _humongous_object_threshold_in_words; 1357 } 1358 1359 // Returns the humongous threshold for a specific region size 1360 static size_t humongous_threshold_for(size_t region_size) { 1361 return (region_size / 2); 1362 } 1363 1364 // Update mod union table with the set of dirty cards. 1365 void updateModUnion(); 1366 1367 // Set the mod union bits corresponding to the given memRegion. Note 1368 // that this is always a safe operation, since it doesn't clear any 1369 // bits. 1370 void markModUnionRange(MemRegion mr); 1371 1372 // Print the maximum heap capacity. 1373 virtual size_t max_capacity() const; 1374 1375 virtual jlong millis_since_last_gc(); 1376 1377 1378 // Convenience function to be used in situations where the heap type can be 1379 // asserted to be this type. 1380 static G1CollectedHeap* heap(); 1381 1382 void set_region_short_lived_locked(HeapRegion* hr); 1383 // add appropriate methods for any other surv rate groups 1384 1385 YoungList* young_list() const { return _young_list; } 1386 1387 // debugging 1388 bool check_young_list_well_formed() { 1389 return _young_list->check_list_well_formed(); 1390 } 1391 1392 bool check_young_list_empty(bool check_heap, 1393 bool check_sample = true); 1394 1395 // *** Stuff related to concurrent marking. It's not clear to me that so 1396 // many of these need to be public. 1397 1398 // The functions below are helper functions that a subclass of 1399 // "CollectedHeap" can use in the implementation of its virtual 1400 // functions. 1401 // This performs a concurrent marking of the live objects in a 1402 // bitmap off to the side. 1403 void doConcurrentMark(); 1404 1405 bool isMarkedPrev(oop obj) const; 1406 bool isMarkedNext(oop obj) const; 1407 1408 // Determine if an object is dead, given the object and also 1409 // the region to which the object belongs. An object is dead 1410 // iff a) it was not allocated since the last mark, b) it 1411 // is not marked, and c) it is not in an archive region. 1412 bool is_obj_dead(const oop obj, const HeapRegion* hr) const { 1413 return 1414 !hr->obj_allocated_since_prev_marking(obj) && 1415 !isMarkedPrev(obj) && 1416 !hr->is_archive(); 1417 } 1418 1419 // This function returns true when an object has been 1420 // around since the previous marking and hasn't yet 1421 // been marked during this marking, and is not in an archive region. 1422 bool is_obj_ill(const oop obj, const HeapRegion* hr) const { 1423 return 1424 !hr->obj_allocated_since_next_marking(obj) && 1425 !isMarkedNext(obj) && 1426 !hr->is_archive(); 1427 } 1428 1429 // Determine if an object is dead, given only the object itself. 1430 // This will find the region to which the object belongs and 1431 // then call the region version of the same function. 1432 1433 // Added if it is NULL it isn't dead. 1434 1435 inline bool is_obj_dead(const oop obj) const; 1436 1437 inline bool is_obj_ill(const oop obj) const; 1438 1439 bool allocated_since_marking(oop obj, HeapRegion* hr, VerifyOption vo); 1440 HeapWord* top_at_mark_start(HeapRegion* hr, VerifyOption vo); 1441 bool is_marked(oop obj, VerifyOption vo); 1442 const char* top_at_mark_start_str(VerifyOption vo); 1443 1444 ConcurrentMark* concurrent_mark() const { return _cm; } 1445 1446 // Refinement 1447 1448 ConcurrentG1Refine* concurrent_g1_refine() const { return _cg1r; } 1449 1450 // The dirty cards region list is used to record a subset of regions 1451 // whose cards need clearing. The list if populated during the 1452 // remembered set scanning and drained during the card table 1453 // cleanup. Although the methods are reentrant, population/draining 1454 // phases must not overlap. For synchronization purposes the last 1455 // element on the list points to itself. 1456 HeapRegion* _dirty_cards_region_list; 1457 void push_dirty_cards_region(HeapRegion* hr); 1458 HeapRegion* pop_dirty_cards_region(); 1459 1460 // Optimized nmethod scanning support routines 1461 1462 // Register the given nmethod with the G1 heap. 1463 virtual void register_nmethod(nmethod* nm); 1464 1465 // Unregister the given nmethod from the G1 heap. 1466 virtual void unregister_nmethod(nmethod* nm); 1467 1468 // Free up superfluous code root memory. 1469 void purge_code_root_memory(); 1470 1471 // Rebuild the strong code root lists for each region 1472 // after a full GC. 1473 void rebuild_strong_code_roots(); 1474 1475 // Delete entries for dead interned string and clean up unreferenced symbols 1476 // in symbol table, possibly in parallel. 1477 void unlink_string_and_symbol_table(BoolObjectClosure* is_alive, bool unlink_strings = true, bool unlink_symbols = true); 1478 1479 // Parallel phase of unloading/cleaning after G1 concurrent mark. 1480 void parallel_cleaning(BoolObjectClosure* is_alive, bool process_strings, bool process_symbols, bool class_unloading_occurred); 1481 1482 // Redirty logged cards in the refinement queue. 1483 void redirty_logged_cards(); 1484 // Verification 1485 1486 // Perform any cleanup actions necessary before allowing a verification. 1487 virtual void prepare_for_verify(); 1488 1489 // Perform verification. 1490 1491 // vo == UsePrevMarking -> use "prev" marking information, 1492 // vo == UseNextMarking -> use "next" marking information 1493 // vo == UseMarkWord -> use the mark word in the object header 1494 // 1495 // NOTE: Only the "prev" marking information is guaranteed to be 1496 // consistent most of the time, so most calls to this should use 1497 // vo == UsePrevMarking. 1498 // Currently, there is only one case where this is called with 1499 // vo == UseNextMarking, which is to verify the "next" marking 1500 // information at the end of remark. 1501 // Currently there is only one place where this is called with 1502 // vo == UseMarkWord, which is to verify the marking during a 1503 // full GC. 1504 void verify(bool silent, VerifyOption vo); 1505 1506 // Override; it uses the "prev" marking information 1507 virtual void verify(bool silent); 1508 1509 // The methods below are here for convenience and dispatch the 1510 // appropriate method depending on value of the given VerifyOption 1511 // parameter. The values for that parameter, and their meanings, 1512 // are the same as those above. 1513 1514 bool is_obj_dead_cond(const oop obj, 1515 const HeapRegion* hr, 1516 const VerifyOption vo) const; 1517 1518 bool is_obj_dead_cond(const oop obj, 1519 const VerifyOption vo) const; 1520 1521 G1HeapSummary create_g1_heap_summary(); 1522 G1EvacSummary create_g1_evac_summary(G1EvacStats* stats); 1523 1524 // Printing 1525 1526 virtual void print_on(outputStream* st) const; 1527 virtual void print_extended_on(outputStream* st) const; 1528 virtual void print_on_error(outputStream* st) const; 1529 1530 virtual void print_gc_threads_on(outputStream* st) const; 1531 virtual void gc_threads_do(ThreadClosure* tc) const; 1532 1533 // Override 1534 void print_tracing_info() const; 1535 1536 // The following two methods are helpful for debugging RSet issues. 1537 void print_cset_rsets() PRODUCT_RETURN; 1538 void print_all_rsets() PRODUCT_RETURN; 1539 1540 public: 1541 size_t pending_card_num(); 1542 1543 protected: 1544 size_t _max_heap_capacity; 1545 }; 1546 1547 #endif // SHARE_VM_GC_G1_G1COLLECTEDHEAP_HPP