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