1 /* 2 * Copyright (c) 2001, 2016, 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_G1CONCURRENTMARK_HPP 26 #define SHARE_VM_GC_G1_G1CONCURRENTMARK_HPP 27 28 #include "classfile/javaClasses.hpp" 29 #include "gc/g1/g1RegionToSpaceMapper.hpp" 30 #include "gc/g1/heapRegionSet.hpp" 31 #include "gc/shared/taskqueue.hpp" 32 33 class G1CollectedHeap; 34 class G1CMBitMap; 35 class G1CMTask; 36 class G1ConcurrentMark; 37 typedef GenericTaskQueue<oop, mtGC> G1CMTaskQueue; 38 typedef GenericTaskQueueSet<G1CMTaskQueue, mtGC> G1CMTaskQueueSet; 39 40 // Closure used by CM during concurrent reference discovery 41 // and reference processing (during remarking) to determine 42 // if a particular object is alive. It is primarily used 43 // to determine if referents of discovered reference objects 44 // are alive. An instance is also embedded into the 45 // reference processor as the _is_alive_non_header field 46 class G1CMIsAliveClosure: public BoolObjectClosure { 47 G1CollectedHeap* _g1; 48 public: 49 G1CMIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) { } 50 51 bool do_object_b(oop obj); 52 }; 53 54 // A generic CM bit map. This is essentially a wrapper around the BitMap 55 // class, with one bit per (1<<_shifter) HeapWords. 56 57 class G1CMBitMapRO VALUE_OBJ_CLASS_SPEC { 58 protected: 59 HeapWord* _bmStartWord; // base address of range covered by map 60 size_t _bmWordSize; // map size (in #HeapWords covered) 61 const int _shifter; // map to char or bit 62 BitMap _bm; // the bit map itself 63 64 public: 65 // constructor 66 G1CMBitMapRO(int shifter); 67 68 // inquiries 69 HeapWord* startWord() const { return _bmStartWord; } 70 // the following is one past the last word in space 71 HeapWord* endWord() const { return _bmStartWord + _bmWordSize; } 72 73 // read marks 74 75 bool isMarked(HeapWord* addr) const { 76 assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize), 77 "outside underlying space?"); 78 return _bm.at(heapWordToOffset(addr)); 79 } 80 81 // iteration 82 inline bool iterate(BitMapClosure* cl, MemRegion mr); 83 84 // Return the address corresponding to the next marked bit at or after 85 // "addr", and before "limit", if "limit" is non-NULL. If there is no 86 // such bit, returns "limit" if that is non-NULL, or else "endWord()". 87 HeapWord* getNextMarkedWordAddress(const HeapWord* addr, 88 const HeapWord* limit = NULL) const; 89 90 // conversion utilities 91 HeapWord* offsetToHeapWord(size_t offset) const { 92 return _bmStartWord + (offset << _shifter); 93 } 94 size_t heapWordToOffset(const HeapWord* addr) const { 95 return pointer_delta(addr, _bmStartWord) >> _shifter; 96 } 97 98 // The argument addr should be the start address of a valid object 99 inline HeapWord* nextObject(HeapWord* addr); 100 101 void print_on_error(outputStream* st, const char* prefix) const; 102 103 // debugging 104 NOT_PRODUCT(bool covers(MemRegion rs) const;) 105 }; 106 107 class G1CMBitMapMappingChangedListener : public G1MappingChangedListener { 108 private: 109 G1CMBitMap* _bm; 110 public: 111 G1CMBitMapMappingChangedListener() : _bm(NULL) {} 112 113 void set_bitmap(G1CMBitMap* bm) { _bm = bm; } 114 115 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled); 116 }; 117 118 class G1CMBitMap : public G1CMBitMapRO { 119 private: 120 G1CMBitMapMappingChangedListener _listener; 121 122 public: 123 static size_t compute_size(size_t heap_size); 124 // Returns the amount of bytes on the heap between two marks in the bitmap. 125 static size_t mark_distance(); 126 // Returns how many bytes (or bits) of the heap a single byte (or bit) of the 127 // mark bitmap corresponds to. This is the same as the mark distance above. 128 static size_t heap_map_factor() { 129 return mark_distance(); 130 } 131 132 G1CMBitMap() : G1CMBitMapRO(LogMinObjAlignment), _listener() { _listener.set_bitmap(this); } 133 134 // Initializes the underlying BitMap to cover the given area. 135 void initialize(MemRegion heap, G1RegionToSpaceMapper* storage); 136 137 // Write marks. 138 inline void mark(HeapWord* addr); 139 inline void clear(HeapWord* addr); 140 inline bool parMark(HeapWord* addr); 141 142 void clearRange(MemRegion mr); 143 144 // Clear the whole mark bitmap. 145 void clearAll(); 146 }; 147 148 // Represents a marking stack used by ConcurrentMarking in the G1 collector. 149 class G1CMMarkStack VALUE_OBJ_CLASS_SPEC { 150 VirtualSpace _virtual_space; // Underlying backing store for actual stack 151 G1ConcurrentMark* _cm; 152 oop* _base; // bottom of stack 153 jint _index; // one more than last occupied index 154 jint _capacity; // max #elements 155 jint _saved_index; // value of _index saved at start of GC 156 157 bool _overflow; 158 bool _should_expand; 159 160 public: 161 G1CMMarkStack(G1ConcurrentMark* cm); 162 ~G1CMMarkStack(); 163 164 bool allocate(size_t capacity); 165 166 // Pushes the first "n" elements of "ptr_arr" on the stack. 167 // Locking impl: concurrency is allowed only with 168 // "par_push_arr" and/or "par_pop_arr" operations, which use the same 169 // locking strategy. 170 void par_push_arr(oop* ptr_arr, int n); 171 172 // If returns false, the array was empty. Otherwise, removes up to "max" 173 // elements from the stack, and transfers them to "ptr_arr" in an 174 // unspecified order. The actual number transferred is given in "n" ("n 175 // == 0" is deliberately redundant with the return value.) Locking impl: 176 // concurrency is allowed only with "par_push_arr" and/or "par_pop_arr" 177 // operations, which use the same locking strategy. 178 bool par_pop_arr(oop* ptr_arr, int max, int* n); 179 180 bool isEmpty() { return _index == 0; } 181 int maxElems() { return _capacity; } 182 183 bool overflow() { return _overflow; } 184 void clear_overflow() { _overflow = false; } 185 186 bool should_expand() const { return _should_expand; } 187 void set_should_expand(); 188 189 // Expand the stack, typically in response to an overflow condition 190 void expand(); 191 192 int size() { return _index; } 193 194 void setEmpty() { _index = 0; clear_overflow(); } 195 196 // Record the current index. 197 void note_start_of_gc(); 198 199 // Make sure that we have not added any entries to the stack during GC. 200 void note_end_of_gc(); 201 202 // Apply fn to each oop in the mark stack, up to the bound recorded 203 // via one of the above "note" functions. The mark stack must not 204 // be modified while iterating. 205 template<typename Fn> void iterate(Fn fn); 206 }; 207 208 class YoungList; 209 210 // Root Regions are regions that are not empty at the beginning of a 211 // marking cycle and which we might collect during an evacuation pause 212 // while the cycle is active. Given that, during evacuation pauses, we 213 // do not copy objects that are explicitly marked, what we have to do 214 // for the root regions is to scan them and mark all objects reachable 215 // from them. According to the SATB assumptions, we only need to visit 216 // each object once during marking. So, as long as we finish this scan 217 // before the next evacuation pause, we can copy the objects from the 218 // root regions without having to mark them or do anything else to them. 219 // 220 // Currently, we only support root region scanning once (at the start 221 // of the marking cycle) and the root regions are all the survivor 222 // regions populated during the initial-mark pause. 223 class G1CMRootRegions VALUE_OBJ_CLASS_SPEC { 224 private: 225 YoungList* _young_list; 226 G1ConcurrentMark* _cm; 227 228 volatile bool _scan_in_progress; 229 volatile bool _should_abort; 230 HeapRegion* volatile _next_survivor; 231 232 void notify_scan_done(); 233 234 public: 235 G1CMRootRegions(); 236 // We actually do most of the initialization in this method. 237 void init(G1CollectedHeap* g1h, G1ConcurrentMark* cm); 238 239 // Reset the claiming / scanning of the root regions. 240 void prepare_for_scan(); 241 242 // Forces get_next() to return NULL so that the iteration aborts early. 243 void abort() { _should_abort = true; } 244 245 // Return true if the CM thread are actively scanning root regions, 246 // false otherwise. 247 bool scan_in_progress() { return _scan_in_progress; } 248 249 // Claim the next root region to scan atomically, or return NULL if 250 // all have been claimed. 251 HeapRegion* claim_next(); 252 253 void cancel_scan(); 254 255 // Flag that we're done with root region scanning and notify anyone 256 // who's waiting on it. If aborted is false, assume that all regions 257 // have been claimed. 258 void scan_finished(); 259 260 // If CM threads are still scanning root regions, wait until they 261 // are done. Return true if we had to wait, false otherwise. 262 bool wait_until_scan_finished(); 263 }; 264 265 class ConcurrentMarkThread; 266 267 class G1ConcurrentMark: public CHeapObj<mtGC> { 268 friend class ConcurrentMarkThread; 269 friend class G1ParNoteEndTask; 270 friend class CalcLiveObjectsClosure; 271 friend class G1CMRefProcTaskProxy; 272 friend class G1CMRefProcTaskExecutor; 273 friend class G1CMKeepAliveAndDrainClosure; 274 friend class G1CMDrainMarkingStackClosure; 275 friend class G1CMBitMapClosure; 276 friend class G1CMConcurrentMarkingTask; 277 friend class G1CMMarkStack; 278 friend class G1CMRemarkTask; 279 friend class G1CMTask; 280 281 protected: 282 ConcurrentMarkThread* _cmThread; // The thread doing the work 283 G1CollectedHeap* _g1h; // The heap 284 uint _parallel_marking_threads; // The number of marking 285 // threads we're using 286 uint _max_parallel_marking_threads; // Max number of marking 287 // threads we'll ever use 288 double _sleep_factor; // How much we have to sleep, with 289 // respect to the work we just did, to 290 // meet the marking overhead goal 291 double _marking_task_overhead; // Marking target overhead for 292 // a single task 293 294 FreeRegionList _cleanup_list; 295 296 // Concurrent marking support structures 297 G1CMBitMap _markBitMap1; 298 G1CMBitMap _markBitMap2; 299 G1CMBitMapRO* _prevMarkBitMap; // Completed mark bitmap 300 G1CMBitMap* _nextMarkBitMap; // Under-construction mark bitmap 301 302 BitMap _region_bm; 303 BitMap _card_bm; 304 305 // Heap bounds 306 HeapWord* _heap_start; 307 HeapWord* _heap_end; 308 309 // Root region tracking and claiming 310 G1CMRootRegions _root_regions; 311 312 // For gray objects 313 G1CMMarkStack _markStack; // Grey objects behind global finger 314 HeapWord* volatile _finger; // The global finger, region aligned, 315 // always points to the end of the 316 // last claimed region 317 318 // Marking tasks 319 uint _max_worker_id;// Maximum worker id 320 uint _active_tasks; // Task num currently active 321 G1CMTask** _tasks; // Task queue array (max_worker_id len) 322 G1CMTaskQueueSet* _task_queues; // Task queue set 323 ParallelTaskTerminator _terminator; // For termination 324 325 // Two sync barriers that are used to synchronize tasks when an 326 // overflow occurs. The algorithm is the following. All tasks enter 327 // the first one to ensure that they have all stopped manipulating 328 // the global data structures. After they exit it, they re-initialize 329 // their data structures and task 0 re-initializes the global data 330 // structures. Then, they enter the second sync barrier. This 331 // ensure, that no task starts doing work before all data 332 // structures (local and global) have been re-initialized. When they 333 // exit it, they are free to start working again. 334 WorkGangBarrierSync _first_overflow_barrier_sync; 335 WorkGangBarrierSync _second_overflow_barrier_sync; 336 337 // This is set by any task, when an overflow on the global data 338 // structures is detected 339 volatile bool _has_overflown; 340 // True: marking is concurrent, false: we're in remark 341 volatile bool _concurrent; 342 // Set at the end of a Full GC so that marking aborts 343 volatile bool _has_aborted; 344 345 // Used when remark aborts due to an overflow to indicate that 346 // another concurrent marking phase should start 347 volatile bool _restart_for_overflow; 348 349 // This is true from the very start of concurrent marking until the 350 // point when all the tasks complete their work. It is really used 351 // to determine the points between the end of concurrent marking and 352 // time of remark. 353 volatile bool _concurrent_marking_in_progress; 354 355 // There would be a race between ConcurrentMarkThread and VMThread(ConcurrentMark::abort()) 356 // to call ConcurrentGCTimer::register_gc_concurrent_end(). 357 // And this variable is used to keep track of concurrent phase. 358 volatile uint _concurrent_phase_status; 359 // Concurrent phase is not yet started. 360 static const uint ConcPhaseNotStarted = 0; 361 // Concurrent phase is started. 362 static const uint ConcPhaseStarted = 1; 363 // Caller thread of ConcurrentGCTimer::register_gc_concurrent_end() is ending concurrent phase. 364 // So other thread should wait until the status to be changed to ConcPhaseNotStarted. 365 static const uint ConcPhaseStopping = 2; 366 367 // All of these times are in ms 368 NumberSeq _init_times; 369 NumberSeq _remark_times; 370 NumberSeq _remark_mark_times; 371 NumberSeq _remark_weak_ref_times; 372 NumberSeq _cleanup_times; 373 double _total_counting_time; 374 double _total_rs_scrub_time; 375 376 double* _accum_task_vtime; // Accumulated task vtime 377 378 WorkGang* _parallel_workers; 379 380 void weakRefsWorkParallelPart(BoolObjectClosure* is_alive, bool purged_classes); 381 void weakRefsWork(bool clear_all_soft_refs); 382 383 void swapMarkBitMaps(); 384 385 // It resets the global marking data structures, as well as the 386 // task local ones; should be called during initial mark. 387 void reset(); 388 389 // Resets all the marking data structures. Called when we have to restart 390 // marking or when marking completes (via set_non_marking_state below). 391 void reset_marking_state(bool clear_overflow = true); 392 393 // We do this after we're done with marking so that the marking data 394 // structures are initialized to a sensible and predictable state. 395 void set_non_marking_state(); 396 397 // Called to indicate how many threads are currently active. 398 void set_concurrency(uint active_tasks); 399 400 // It should be called to indicate which phase we're in (concurrent 401 // mark or remark) and how many threads are currently active. 402 void set_concurrency_and_phase(uint active_tasks, bool concurrent); 403 404 // Prints all gathered CM-related statistics 405 void print_stats(); 406 407 bool cleanup_list_is_empty() { 408 return _cleanup_list.is_empty(); 409 } 410 411 // Accessor methods 412 uint parallel_marking_threads() const { return _parallel_marking_threads; } 413 uint max_parallel_marking_threads() const { return _max_parallel_marking_threads;} 414 double sleep_factor() { return _sleep_factor; } 415 double marking_task_overhead() { return _marking_task_overhead;} 416 417 HeapWord* finger() { return _finger; } 418 bool concurrent() { return _concurrent; } 419 uint active_tasks() { return _active_tasks; } 420 ParallelTaskTerminator* terminator() { return &_terminator; } 421 422 // It claims the next available region to be scanned by a marking 423 // task/thread. It might return NULL if the next region is empty or 424 // we have run out of regions. In the latter case, out_of_regions() 425 // determines whether we've really run out of regions or the task 426 // should call claim_region() again. This might seem a bit 427 // awkward. Originally, the code was written so that claim_region() 428 // either successfully returned with a non-empty region or there 429 // were no more regions to be claimed. The problem with this was 430 // that, in certain circumstances, it iterated over large chunks of 431 // the heap finding only empty regions and, while it was working, it 432 // was preventing the calling task to call its regular clock 433 // method. So, this way, each task will spend very little time in 434 // claim_region() and is allowed to call the regular clock method 435 // frequently. 436 HeapRegion* claim_region(uint worker_id); 437 438 // It determines whether we've run out of regions to scan. Note that 439 // the finger can point past the heap end in case the heap was expanded 440 // to satisfy an allocation without doing a GC. This is fine, because all 441 // objects in those regions will be considered live anyway because of 442 // SATB guarantees (i.e. their TAMS will be equal to bottom). 443 bool out_of_regions() { return _finger >= _heap_end; } 444 445 // Returns the task with the given id 446 G1CMTask* task(int id) { 447 assert(0 <= id && id < (int) _active_tasks, 448 "task id not within active bounds"); 449 return _tasks[id]; 450 } 451 452 // Returns the task queue with the given id 453 G1CMTaskQueue* task_queue(int id) { 454 assert(0 <= id && id < (int) _active_tasks, 455 "task queue id not within active bounds"); 456 return (G1CMTaskQueue*) _task_queues->queue(id); 457 } 458 459 // Returns the task queue set 460 G1CMTaskQueueSet* task_queues() { return _task_queues; } 461 462 // Access / manipulation of the overflow flag which is set to 463 // indicate that the global stack has overflown 464 bool has_overflown() { return _has_overflown; } 465 void set_has_overflown() { _has_overflown = true; } 466 void clear_has_overflown() { _has_overflown = false; } 467 bool restart_for_overflow() { return _restart_for_overflow; } 468 469 // Methods to enter the two overflow sync barriers 470 void enter_first_sync_barrier(uint worker_id); 471 void enter_second_sync_barrier(uint worker_id); 472 473 // Live Data Counting data structures... 474 // These data structures are initialized at the start of 475 // marking. They are written to while marking is active. 476 // They are aggregated during remark; the aggregated values 477 // are then used to populate the _region_bm, _card_bm, and 478 // the total live bytes, which are then subsequently updated 479 // during cleanup. 480 481 // An array of bitmaps (one bit map per task). Each bitmap 482 // is used to record the cards spanned by the live objects 483 // marked by that task/worker. 484 BitMap* _count_card_bitmaps; 485 486 // Used to record the number of marked live bytes 487 // (for each region, by worker thread). 488 size_t** _count_marked_bytes; 489 490 // Card index of the bottom of the G1 heap. Used for biasing indices into 491 // the card bitmaps. 492 intptr_t _heap_bottom_card_num; 493 494 // Set to true when initialization is complete 495 bool _completed_initialization; 496 497 // end_timer, true to end gc timer after ending concurrent phase. 498 void register_concurrent_phase_end_common(bool end_timer); 499 500 public: 501 // Manipulation of the global mark stack. 502 // The push and pop operations are used by tasks for transfers 503 // between task-local queues and the global mark stack, and use 504 // locking for concurrency safety. 505 bool mark_stack_push(oop* arr, int n) { 506 _markStack.par_push_arr(arr, n); 507 if (_markStack.overflow()) { 508 set_has_overflown(); 509 return false; 510 } 511 return true; 512 } 513 void mark_stack_pop(oop* arr, int max, int* n) { 514 _markStack.par_pop_arr(arr, max, n); 515 } 516 size_t mark_stack_size() { return _markStack.size(); } 517 size_t partial_mark_stack_size_target() { return _markStack.maxElems()/3; } 518 bool mark_stack_overflow() { return _markStack.overflow(); } 519 bool mark_stack_empty() { return _markStack.isEmpty(); } 520 521 G1CMRootRegions* root_regions() { return &_root_regions; } 522 523 bool concurrent_marking_in_progress() { 524 return _concurrent_marking_in_progress; 525 } 526 void set_concurrent_marking_in_progress() { 527 _concurrent_marking_in_progress = true; 528 } 529 void clear_concurrent_marking_in_progress() { 530 _concurrent_marking_in_progress = false; 531 } 532 533 void register_concurrent_phase_start(const char* title); 534 void register_concurrent_phase_end(); 535 // Ends both concurrent phase and timer. 536 void register_concurrent_gc_end_and_stop_timer(); 537 538 void update_accum_task_vtime(int i, double vtime) { 539 _accum_task_vtime[i] += vtime; 540 } 541 542 double all_task_accum_vtime() { 543 double ret = 0.0; 544 for (uint i = 0; i < _max_worker_id; ++i) 545 ret += _accum_task_vtime[i]; 546 return ret; 547 } 548 549 // Attempts to steal an object from the task queues of other tasks 550 bool try_stealing(uint worker_id, int* hash_seed, oop& obj); 551 552 G1ConcurrentMark(G1CollectedHeap* g1h, 553 G1RegionToSpaceMapper* prev_bitmap_storage, 554 G1RegionToSpaceMapper* next_bitmap_storage); 555 ~G1ConcurrentMark(); 556 557 ConcurrentMarkThread* cmThread() { return _cmThread; } 558 559 G1CMBitMapRO* prevMarkBitMap() const { return _prevMarkBitMap; } 560 G1CMBitMap* nextMarkBitMap() const { return _nextMarkBitMap; } 561 562 // Returns the number of GC threads to be used in a concurrent 563 // phase based on the number of GC threads being used in a STW 564 // phase. 565 uint scale_parallel_threads(uint n_par_threads); 566 567 // Calculates the number of GC threads to be used in a concurrent phase. 568 uint calc_parallel_marking_threads(); 569 570 // The following three are interaction between CM and 571 // G1CollectedHeap 572 573 // This notifies CM that a root during initial-mark needs to be 574 // grayed. It is MT-safe. word_size is the size of the object in 575 // words. It is passed explicitly as sometimes we cannot calculate 576 // it from the given object because it might be in an inconsistent 577 // state (e.g., in to-space and being copied). So the caller is 578 // responsible for dealing with this issue (e.g., get the size from 579 // the from-space image when the to-space image might be 580 // inconsistent) and always passing the size. hr is the region that 581 // contains the object and it's passed optionally from callers who 582 // might already have it (no point in recalculating it). 583 inline void grayRoot(oop obj, 584 size_t word_size, 585 uint worker_id, 586 HeapRegion* hr = NULL); 587 588 // Clear the next marking bitmap (will be called concurrently). 589 void clearNextBitmap(); 590 591 // Return whether the next mark bitmap has no marks set. To be used for assertions 592 // only. Will not yield to pause requests. 593 bool nextMarkBitmapIsClear(); 594 595 // These two do the work that needs to be done before and after the 596 // initial root checkpoint. Since this checkpoint can be done at two 597 // different points (i.e. an explicit pause or piggy-backed on a 598 // young collection), then it's nice to be able to easily share the 599 // pre/post code. It might be the case that we can put everything in 600 // the post method. TP 601 void checkpointRootsInitialPre(); 602 void checkpointRootsInitialPost(); 603 604 // Scan all the root regions and mark everything reachable from 605 // them. 606 void scanRootRegions(); 607 608 // Scan a single root region and mark everything reachable from it. 609 void scanRootRegion(HeapRegion* hr, uint worker_id); 610 611 // Do concurrent phase of marking, to a tentative transitive closure. 612 void markFromRoots(); 613 614 void checkpointRootsFinal(bool clear_all_soft_refs); 615 void checkpointRootsFinalWork(); 616 void cleanup(); 617 void completeCleanup(); 618 619 // Mark in the previous bitmap. NB: this is usually read-only, so use 620 // this carefully! 621 inline void markPrev(oop p); 622 623 // Clears marks for all objects in the given range, for the prev or 624 // next bitmaps. NB: the previous bitmap is usually 625 // read-only, so use this carefully! 626 void clearRangePrevBitmap(MemRegion mr); 627 628 // Notify data structures that a GC has started. 629 void note_start_of_gc() { 630 _markStack.note_start_of_gc(); 631 } 632 633 // Notify data structures that a GC is finished. 634 void note_end_of_gc() { 635 _markStack.note_end_of_gc(); 636 } 637 638 // Verify that there are no CSet oops on the stacks (taskqueues / 639 // global mark stack) and fingers (global / per-task). 640 // If marking is not in progress, it's a no-op. 641 void verify_no_cset_oops() PRODUCT_RETURN; 642 643 inline bool isPrevMarked(oop p) const; 644 645 inline bool do_yield_check(uint worker_i = 0); 646 647 // Called to abort the marking cycle after a Full GC takes place. 648 void abort(); 649 650 bool has_aborted() { return _has_aborted; } 651 652 void print_summary_info(); 653 654 void print_worker_threads_on(outputStream* st) const; 655 656 void print_on_error(outputStream* st) const; 657 658 // Liveness counting 659 660 // Utility routine to set an exclusive range of cards on the given 661 // card liveness bitmap 662 inline void set_card_bitmap_range(BitMap* card_bm, 663 BitMap::idx_t start_idx, 664 BitMap::idx_t end_idx, 665 bool is_par); 666 667 // Returns the card number of the bottom of the G1 heap. 668 // Used in biasing indices into accounting card bitmaps. 669 intptr_t heap_bottom_card_num() const { 670 return _heap_bottom_card_num; 671 } 672 673 // Returns the card bitmap for a given task or worker id. 674 BitMap* count_card_bitmap_for(uint worker_id) { 675 assert(worker_id < _max_worker_id, "oob"); 676 assert(_count_card_bitmaps != NULL, "uninitialized"); 677 BitMap* task_card_bm = &_count_card_bitmaps[worker_id]; 678 assert(task_card_bm->size() == _card_bm.size(), "size mismatch"); 679 return task_card_bm; 680 } 681 682 // Returns the array containing the marked bytes for each region, 683 // for the given worker or task id. 684 size_t* count_marked_bytes_array_for(uint worker_id) { 685 assert(worker_id < _max_worker_id, "oob"); 686 assert(_count_marked_bytes != NULL, "uninitialized"); 687 size_t* marked_bytes_array = _count_marked_bytes[worker_id]; 688 assert(marked_bytes_array != NULL, "uninitialized"); 689 return marked_bytes_array; 690 } 691 692 // Returns the index in the liveness accounting card table bitmap 693 // for the given address 694 inline BitMap::idx_t card_bitmap_index_for(HeapWord* addr); 695 696 // Counts the size of the given memory region in the the given 697 // marked_bytes array slot for the given HeapRegion. 698 // Sets the bits in the given card bitmap that are associated with the 699 // cards that are spanned by the memory region. 700 inline void count_region(MemRegion mr, 701 HeapRegion* hr, 702 size_t* marked_bytes_array, 703 BitMap* task_card_bm); 704 705 // Counts the given object in the given task/worker counting 706 // data structures. 707 inline void count_object(oop obj, 708 HeapRegion* hr, 709 size_t* marked_bytes_array, 710 BitMap* task_card_bm, 711 size_t word_size); 712 713 // Attempts to mark the given object and, if successful, counts 714 // the object in the given task/worker counting structures. 715 inline bool par_mark_and_count(oop obj, 716 HeapRegion* hr, 717 size_t* marked_bytes_array, 718 BitMap* task_card_bm); 719 720 // Attempts to mark the given object and, if successful, counts 721 // the object in the task/worker counting structures for the 722 // given worker id. 723 inline bool par_mark_and_count(oop obj, 724 size_t word_size, 725 HeapRegion* hr, 726 uint worker_id); 727 728 // Returns true if initialization was successfully completed. 729 bool completed_initialization() const { 730 return _completed_initialization; 731 } 732 733 protected: 734 // Clear all the per-task bitmaps and arrays used to store the 735 // counting data. 736 void clear_all_count_data(); 737 738 // Aggregates the counting data for each worker/task 739 // that was constructed while marking. Also sets 740 // the amount of marked bytes for each region and 741 // the top at concurrent mark count. 742 void aggregate_count_data(); 743 744 // Verification routine 745 void verify_count_data(); 746 }; 747 748 // A class representing a marking task. 749 class G1CMTask : public TerminatorTerminator { 750 private: 751 enum PrivateConstants { 752 // the regular clock call is called once the scanned words reaches 753 // this limit 754 words_scanned_period = 12*1024, 755 // the regular clock call is called once the number of visited 756 // references reaches this limit 757 refs_reached_period = 384, 758 // initial value for the hash seed, used in the work stealing code 759 init_hash_seed = 17, 760 // how many entries will be transferred between global stack and 761 // local queues 762 global_stack_transfer_size = 16 763 }; 764 765 uint _worker_id; 766 G1CollectedHeap* _g1h; 767 G1ConcurrentMark* _cm; 768 G1CMBitMap* _nextMarkBitMap; 769 // the task queue of this task 770 G1CMTaskQueue* _task_queue; 771 private: 772 // the task queue set---needed for stealing 773 G1CMTaskQueueSet* _task_queues; 774 // indicates whether the task has been claimed---this is only for 775 // debugging purposes 776 bool _claimed; 777 778 // number of calls to this task 779 int _calls; 780 781 // when the virtual timer reaches this time, the marking step should 782 // exit 783 double _time_target_ms; 784 // the start time of the current marking step 785 double _start_time_ms; 786 787 // the oop closure used for iterations over oops 788 G1CMOopClosure* _cm_oop_closure; 789 790 // the region this task is scanning, NULL if we're not scanning any 791 HeapRegion* _curr_region; 792 // the local finger of this task, NULL if we're not scanning a region 793 HeapWord* _finger; 794 // limit of the region this task is scanning, NULL if we're not scanning one 795 HeapWord* _region_limit; 796 797 // the number of words this task has scanned 798 size_t _words_scanned; 799 // When _words_scanned reaches this limit, the regular clock is 800 // called. Notice that this might be decreased under certain 801 // circumstances (i.e. when we believe that we did an expensive 802 // operation). 803 size_t _words_scanned_limit; 804 // the initial value of _words_scanned_limit (i.e. what it was 805 // before it was decreased). 806 size_t _real_words_scanned_limit; 807 808 // the number of references this task has visited 809 size_t _refs_reached; 810 // When _refs_reached reaches this limit, the regular clock is 811 // called. Notice this this might be decreased under certain 812 // circumstances (i.e. when we believe that we did an expensive 813 // operation). 814 size_t _refs_reached_limit; 815 // the initial value of _refs_reached_limit (i.e. what it was before 816 // it was decreased). 817 size_t _real_refs_reached_limit; 818 819 // used by the work stealing stuff 820 int _hash_seed; 821 // if this is true, then the task has aborted for some reason 822 bool _has_aborted; 823 // set when the task aborts because it has met its time quota 824 bool _has_timed_out; 825 // true when we're draining SATB buffers; this avoids the task 826 // aborting due to SATB buffers being available (as we're already 827 // dealing with them) 828 bool _draining_satb_buffers; 829 830 // number sequence of past step times 831 NumberSeq _step_times_ms; 832 // elapsed time of this task 833 double _elapsed_time_ms; 834 // termination time of this task 835 double _termination_time_ms; 836 // when this task got into the termination protocol 837 double _termination_start_time_ms; 838 839 // true when the task is during a concurrent phase, false when it is 840 // in the remark phase (so, in the latter case, we do not have to 841 // check all the things that we have to check during the concurrent 842 // phase, i.e. SATB buffer availability...) 843 bool _concurrent; 844 845 TruncatedSeq _marking_step_diffs_ms; 846 847 // Counting data structures. Embedding the task's marked_bytes_array 848 // and card bitmap into the actual task saves having to go through 849 // the ConcurrentMark object. 850 size_t* _marked_bytes_array; 851 BitMap* _card_bm; 852 853 // it updates the local fields after this task has claimed 854 // a new region to scan 855 void setup_for_region(HeapRegion* hr); 856 // it brings up-to-date the limit of the region 857 void update_region_limit(); 858 859 // called when either the words scanned or the refs visited limit 860 // has been reached 861 void reached_limit(); 862 // recalculates the words scanned and refs visited limits 863 void recalculate_limits(); 864 // decreases the words scanned and refs visited limits when we reach 865 // an expensive operation 866 void decrease_limits(); 867 // it checks whether the words scanned or refs visited reached their 868 // respective limit and calls reached_limit() if they have 869 void check_limits() { 870 if (_words_scanned >= _words_scanned_limit || 871 _refs_reached >= _refs_reached_limit) { 872 reached_limit(); 873 } 874 } 875 // this is supposed to be called regularly during a marking step as 876 // it checks a bunch of conditions that might cause the marking step 877 // to abort 878 void regular_clock_call(); 879 bool concurrent() { return _concurrent; } 880 881 // Test whether obj might have already been passed over by the 882 // mark bitmap scan, and so needs to be pushed onto the mark stack. 883 bool is_below_finger(oop obj, HeapWord* global_finger) const; 884 885 template<bool scan> void process_grey_object(oop obj); 886 887 public: 888 // It resets the task; it should be called right at the beginning of 889 // a marking phase. 890 void reset(G1CMBitMap* _nextMarkBitMap); 891 // it clears all the fields that correspond to a claimed region. 892 void clear_region_fields(); 893 894 void set_concurrent(bool concurrent) { _concurrent = concurrent; } 895 896 // The main method of this class which performs a marking step 897 // trying not to exceed the given duration. However, it might exit 898 // prematurely, according to some conditions (i.e. SATB buffers are 899 // available for processing). 900 void do_marking_step(double target_ms, 901 bool do_termination, 902 bool is_serial); 903 904 // These two calls start and stop the timer 905 void record_start_time() { 906 _elapsed_time_ms = os::elapsedTime() * 1000.0; 907 } 908 void record_end_time() { 909 _elapsed_time_ms = os::elapsedTime() * 1000.0 - _elapsed_time_ms; 910 } 911 912 // returns the worker ID associated with this task. 913 uint worker_id() { return _worker_id; } 914 915 // From TerminatorTerminator. It determines whether this task should 916 // exit the termination protocol after it's entered it. 917 virtual bool should_exit_termination(); 918 919 // Resets the local region fields after a task has finished scanning a 920 // region; or when they have become stale as a result of the region 921 // being evacuated. 922 void giveup_current_region(); 923 924 HeapWord* finger() { return _finger; } 925 926 bool has_aborted() { return _has_aborted; } 927 void set_has_aborted() { _has_aborted = true; } 928 void clear_has_aborted() { _has_aborted = false; } 929 bool has_timed_out() { return _has_timed_out; } 930 bool claimed() { return _claimed; } 931 932 void set_cm_oop_closure(G1CMOopClosure* cm_oop_closure); 933 934 // Increment the number of references this task has visited. 935 void increment_refs_reached() { ++_refs_reached; } 936 937 // Grey the object by marking it. If not already marked, push it on 938 // the local queue if below the finger. 939 // Precondition: obj is in region. 940 // Precondition: obj is below region's NTAMS. 941 inline void make_reference_grey(oop obj, HeapRegion* region); 942 943 // Grey the object (by calling make_grey_reference) if required, 944 // e.g. obj is below its containing region's NTAMS. 945 // Precondition: obj is a valid heap object. 946 inline void deal_with_reference(oop obj); 947 948 // It scans an object and visits its children. 949 inline void scan_object(oop obj); 950 951 // It pushes an object on the local queue. 952 inline void push(oop obj); 953 954 // These two move entries to/from the global stack. 955 void move_entries_to_global_stack(); 956 void get_entries_from_global_stack(); 957 958 // It pops and scans objects from the local queue. If partially is 959 // true, then it stops when the queue size is of a given limit. If 960 // partially is false, then it stops when the queue is empty. 961 void drain_local_queue(bool partially); 962 // It moves entries from the global stack to the local queue and 963 // drains the local queue. If partially is true, then it stops when 964 // both the global stack and the local queue reach a given size. If 965 // partially if false, it tries to empty them totally. 966 void drain_global_stack(bool partially); 967 // It keeps picking SATB buffers and processing them until no SATB 968 // buffers are available. 969 void drain_satb_buffers(); 970 971 // moves the local finger to a new location 972 inline void move_finger_to(HeapWord* new_finger) { 973 assert(new_finger >= _finger && new_finger < _region_limit, "invariant"); 974 _finger = new_finger; 975 } 976 977 G1CMTask(uint worker_id, 978 G1ConcurrentMark *cm, 979 size_t* marked_bytes, 980 BitMap* card_bm, 981 G1CMTaskQueue* task_queue, 982 G1CMTaskQueueSet* task_queues); 983 984 // it prints statistics associated with this task 985 void print_stats(); 986 }; 987 988 // Class that's used to to print out per-region liveness 989 // information. It's currently used at the end of marking and also 990 // after we sort the old regions at the end of the cleanup operation. 991 class G1PrintRegionLivenessInfoClosure: public HeapRegionClosure { 992 private: 993 // Accumulators for these values. 994 size_t _total_used_bytes; 995 size_t _total_capacity_bytes; 996 size_t _total_prev_live_bytes; 997 size_t _total_next_live_bytes; 998 999 // These are set up when we come across a "stars humongous" region 1000 // (as this is where most of this information is stored, not in the 1001 // subsequent "continues humongous" regions). After that, for every 1002 // region in a given humongous region series we deduce the right 1003 // values for it by simply subtracting the appropriate amount from 1004 // these fields. All these values should reach 0 after we've visited 1005 // the last region in the series. 1006 size_t _hum_used_bytes; 1007 size_t _hum_capacity_bytes; 1008 size_t _hum_prev_live_bytes; 1009 size_t _hum_next_live_bytes; 1010 1011 // Accumulator for the remembered set size 1012 size_t _total_remset_bytes; 1013 1014 // Accumulator for strong code roots memory size 1015 size_t _total_strong_code_roots_bytes; 1016 1017 static double perc(size_t val, size_t total) { 1018 if (total == 0) { 1019 return 0.0; 1020 } else { 1021 return 100.0 * ((double) val / (double) total); 1022 } 1023 } 1024 1025 static double bytes_to_mb(size_t val) { 1026 return (double) val / (double) M; 1027 } 1028 1029 // See the .cpp file. 1030 size_t get_hum_bytes(size_t* hum_bytes); 1031 void get_hum_bytes(size_t* used_bytes, size_t* capacity_bytes, 1032 size_t* prev_live_bytes, size_t* next_live_bytes); 1033 1034 public: 1035 // The header and footer are printed in the constructor and 1036 // destructor respectively. 1037 G1PrintRegionLivenessInfoClosure(const char* phase_name); 1038 virtual bool doHeapRegion(HeapRegion* r); 1039 ~G1PrintRegionLivenessInfoClosure(); 1040 }; 1041 1042 #endif // SHARE_VM_GC_G1_G1CONCURRENTMARK_HPP