1 /*
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   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.
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   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  *
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  24 
  25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARK_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARK_HPP
  27 
  28 #include "gc_implementation/g1/heapRegionSets.hpp"
  29 #include "utilities/taskqueue.hpp"
  30 
  31 class G1CollectedHeap;
  32 class CMTask;
  33 typedef GenericTaskQueue<oop, mtGC>            CMTaskQueue;
  34 typedef GenericTaskQueueSet<CMTaskQueue, mtGC> CMTaskQueueSet;
  35 
  36 // Closure used by CM during concurrent reference discovery
  37 // and reference processing (during remarking) to determine
  38 // if a particular object is alive. It is primarily used
  39 // to determine if referents of discovered reference objects
  40 // are alive. An instance is also embedded into the
  41 // reference processor as the _is_alive_non_header field
  42 class G1CMIsAliveClosure: public BoolObjectClosure {
  43   G1CollectedHeap* _g1;
  44  public:
  45   G1CMIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) { }
  46 
  47   void do_object(oop obj) {
  48     ShouldNotCallThis();
  49   }
  50   bool do_object_b(oop obj);
  51 };
  52 
  53 // A generic CM bit map.  This is essentially a wrapper around the BitMap
  54 // class, with one bit per (1<<_shifter) HeapWords.
  55 
  56 class CMBitMapRO VALUE_OBJ_CLASS_SPEC {
  57  protected:
  58   HeapWord* _bmStartWord;      // base address of range covered by map
  59   size_t    _bmWordSize;       // map size (in #HeapWords covered)
  60   const int _shifter;          // map to char or bit
  61   VirtualSpace _virtual_space; // underlying the bit map
  62   BitMap    _bm;               // the bit map itself
  63 
  64  public:
  65   // constructor
  66   CMBitMapRO(int shifter);
  67 
  68   enum { do_yield = true };
  69 
  70   // inquiries
  71   HeapWord* startWord()   const { return _bmStartWord; }
  72   size_t    sizeInWords() const { return _bmWordSize;  }
  73   // the following is one past the last word in space
  74   HeapWord* endWord()     const { return _bmStartWord + _bmWordSize; }
  75 
  76   // read marks
  77 
  78   bool isMarked(HeapWord* addr) const {
  79     assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
  80            "outside underlying space?");
  81     return _bm.at(heapWordToOffset(addr));
  82   }
  83 
  84   // iteration
  85   inline bool iterate(BitMapClosure* cl, MemRegion mr);
  86   inline bool iterate(BitMapClosure* cl);
  87 
  88   // Return the address corresponding to the next marked bit at or after
  89   // "addr", and before "limit", if "limit" is non-NULL.  If there is no
  90   // such bit, returns "limit" if that is non-NULL, or else "endWord()".
  91   HeapWord* getNextMarkedWordAddress(HeapWord* addr,
  92                                      HeapWord* limit = NULL) const;
  93   // Return the address corresponding to the next unmarked bit at or after
  94   // "addr", and before "limit", if "limit" is non-NULL.  If there is no
  95   // such bit, returns "limit" if that is non-NULL, or else "endWord()".
  96   HeapWord* getNextUnmarkedWordAddress(HeapWord* addr,
  97                                        HeapWord* limit = NULL) const;
  98 
  99   // conversion utilities
 100   HeapWord* offsetToHeapWord(size_t offset) const {
 101     return _bmStartWord + (offset << _shifter);
 102   }
 103   size_t heapWordToOffset(HeapWord* addr) const {
 104     return pointer_delta(addr, _bmStartWord) >> _shifter;
 105   }
 106   int heapWordDiffToOffsetDiff(size_t diff) const;
 107 
 108   // The argument addr should be the start address of a valid object
 109   HeapWord* nextObject(HeapWord* addr) {
 110     oop obj = (oop) addr;
 111     HeapWord* res =  addr + obj->size();
 112     assert(offsetToHeapWord(heapWordToOffset(res)) == res, "sanity");
 113     return res;
 114   }
 115 
 116   // debugging
 117   NOT_PRODUCT(bool covers(ReservedSpace rs) const;)
 118 };
 119 
 120 class CMBitMap : public CMBitMapRO {
 121 
 122  public:
 123   // constructor
 124   CMBitMap(int shifter) :
 125     CMBitMapRO(shifter) {}
 126 
 127   // Allocates the back store for the marking bitmap
 128   bool allocate(ReservedSpace heap_rs);
 129 
 130   // write marks
 131   void mark(HeapWord* addr) {
 132     assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
 133            "outside underlying space?");
 134     _bm.set_bit(heapWordToOffset(addr));
 135   }
 136   void clear(HeapWord* addr) {
 137     assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
 138            "outside underlying space?");
 139     _bm.clear_bit(heapWordToOffset(addr));
 140   }
 141   bool parMark(HeapWord* addr) {
 142     assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
 143            "outside underlying space?");
 144     return _bm.par_set_bit(heapWordToOffset(addr));
 145   }
 146   bool parClear(HeapWord* addr) {
 147     assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
 148            "outside underlying space?");
 149     return _bm.par_clear_bit(heapWordToOffset(addr));
 150   }
 151   void markRange(MemRegion mr);
 152   void clearAll();
 153   void clearRange(MemRegion mr);
 154 
 155   // Starting at the bit corresponding to "addr" (inclusive), find the next
 156   // "1" bit, if any.  This bit starts some run of consecutive "1"'s; find
 157   // the end of this run (stopping at "end_addr").  Return the MemRegion
 158   // covering from the start of the region corresponding to the first bit
 159   // of the run to the end of the region corresponding to the last bit of
 160   // the run.  If there is no "1" bit at or after "addr", return an empty
 161   // MemRegion.
 162   MemRegion getAndClearMarkedRegion(HeapWord* addr, HeapWord* end_addr);
 163 };
 164 
 165 // Represents a marking stack used by ConcurrentMarking in the G1 collector.
 166 class CMMarkStack VALUE_OBJ_CLASS_SPEC {
 167   VirtualSpace _virtual_space;   // Underlying backing store for actual stack
 168   ConcurrentMark* _cm;
 169   oop*   _base;        // bottom of stack
 170   jint _index;       // one more than last occupied index
 171   jint _capacity;    // max #elements
 172   jint _saved_index; // value of _index saved at start of GC
 173   NOT_PRODUCT(jint _max_depth;)   // max depth plumbed during run
 174 
 175   bool  _overflow;
 176   bool  _should_expand;
 177   DEBUG_ONLY(bool _drain_in_progress;)
 178   DEBUG_ONLY(bool _drain_in_progress_yields;)
 179 
 180  public:
 181   CMMarkStack(ConcurrentMark* cm);
 182   ~CMMarkStack();
 183 
 184 #ifndef PRODUCT
 185   jint max_depth() const {
 186     return _max_depth;
 187   }
 188 #endif
 189 
 190   bool allocate(size_t capacity);
 191 
 192   oop pop() {
 193     if (!isEmpty()) {
 194       return _base[--_index] ;
 195     }
 196     return NULL;
 197   }
 198 
 199   // If overflow happens, don't do the push, and record the overflow.
 200   // *Requires* that "ptr" is already marked.
 201   void push(oop ptr) {
 202     if (isFull()) {
 203       // Record overflow.
 204       _overflow = true;
 205       return;
 206     } else {
 207       _base[_index++] = ptr;
 208       NOT_PRODUCT(_max_depth = MAX2(_max_depth, _index));
 209     }
 210   }
 211   // Non-block impl.  Note: concurrency is allowed only with other
 212   // "par_push" operations, not with "pop" or "drain".  We would need
 213   // parallel versions of them if such concurrency was desired.
 214   void par_push(oop ptr);
 215 
 216   // Pushes the first "n" elements of "ptr_arr" on the stack.
 217   // Non-block impl.  Note: concurrency is allowed only with other
 218   // "par_adjoin_arr" or "push" operations, not with "pop" or "drain".
 219   void par_adjoin_arr(oop* ptr_arr, int n);
 220 
 221   // Pushes the first "n" elements of "ptr_arr" on the stack.
 222   // Locking impl: concurrency is allowed only with
 223   // "par_push_arr" and/or "par_pop_arr" operations, which use the same
 224   // locking strategy.
 225   void par_push_arr(oop* ptr_arr, int n);
 226 
 227   // If returns false, the array was empty.  Otherwise, removes up to "max"
 228   // elements from the stack, and transfers them to "ptr_arr" in an
 229   // unspecified order.  The actual number transferred is given in "n" ("n
 230   // == 0" is deliberately redundant with the return value.)  Locking impl:
 231   // concurrency is allowed only with "par_push_arr" and/or "par_pop_arr"
 232   // operations, which use the same locking strategy.
 233   bool par_pop_arr(oop* ptr_arr, int max, int* n);
 234 
 235   // Drain the mark stack, applying the given closure to all fields of
 236   // objects on the stack.  (That is, continue until the stack is empty,
 237   // even if closure applications add entries to the stack.)  The "bm"
 238   // argument, if non-null, may be used to verify that only marked objects
 239   // are on the mark stack.  If "yield_after" is "true", then the
 240   // concurrent marker performing the drain offers to yield after
 241   // processing each object.  If a yield occurs, stops the drain operation
 242   // and returns false.  Otherwise, returns true.
 243   template<class OopClosureClass>
 244   bool drain(OopClosureClass* cl, CMBitMap* bm, bool yield_after = false);
 245 
 246   bool isEmpty()    { return _index == 0; }
 247   bool isFull()     { return _index == _capacity; }
 248   int  maxElems()   { return _capacity; }
 249 
 250   bool overflow() { return _overflow; }
 251   void clear_overflow() { _overflow = false; }
 252 
 253   bool should_expand() const { return _should_expand; }
 254   void set_should_expand();
 255 
 256   // Expand the stack, typically in response to an overflow condition
 257   void expand();
 258 
 259   int  size() { return _index; }
 260 
 261   void setEmpty()   { _index = 0; clear_overflow(); }
 262 
 263   // Record the current index.
 264   void note_start_of_gc();
 265 
 266   // Make sure that we have not added any entries to the stack during GC.
 267   void note_end_of_gc();
 268 
 269   // iterate over the oops in the mark stack, up to the bound recorded via
 270   // the call above.
 271   void oops_do(OopClosure* f);
 272 };
 273 
 274 class ForceOverflowSettings VALUE_OBJ_CLASS_SPEC {
 275 private:
 276 #ifndef PRODUCT
 277   uintx _num_remaining;
 278   bool _force;
 279 #endif // !defined(PRODUCT)
 280 
 281 public:
 282   void init() PRODUCT_RETURN;
 283   void update() PRODUCT_RETURN;
 284   bool should_force() PRODUCT_RETURN_( return false; );
 285 };
 286 
 287 // this will enable a variety of different statistics per GC task
 288 #define _MARKING_STATS_       0
 289 // this will enable the higher verbose levels
 290 #define _MARKING_VERBOSE_     0
 291 
 292 #if _MARKING_STATS_
 293 #define statsOnly(statement)  \
 294 do {                          \
 295   statement ;                 \
 296 } while (0)
 297 #else // _MARKING_STATS_
 298 #define statsOnly(statement)  \
 299 do {                          \
 300 } while (0)
 301 #endif // _MARKING_STATS_
 302 
 303 typedef enum {
 304   no_verbose  = 0,   // verbose turned off
 305   stats_verbose,     // only prints stats at the end of marking
 306   low_verbose,       // low verbose, mostly per region and per major event
 307   medium_verbose,    // a bit more detailed than low
 308   high_verbose       // per object verbose
 309 } CMVerboseLevel;
 310 
 311 class YoungList;
 312 
 313 // Root Regions are regions that are not empty at the beginning of a
 314 // marking cycle and which we might collect during an evacuation pause
 315 // while the cycle is active. Given that, during evacuation pauses, we
 316 // do not copy objects that are explicitly marked, what we have to do
 317 // for the root regions is to scan them and mark all objects reachable
 318 // from them. According to the SATB assumptions, we only need to visit
 319 // each object once during marking. So, as long as we finish this scan
 320 // before the next evacuation pause, we can copy the objects from the
 321 // root regions without having to mark them or do anything else to them.
 322 //
 323 // Currently, we only support root region scanning once (at the start
 324 // of the marking cycle) and the root regions are all the survivor
 325 // regions populated during the initial-mark pause.
 326 class CMRootRegions VALUE_OBJ_CLASS_SPEC {
 327 private:
 328   YoungList*           _young_list;
 329   ConcurrentMark*      _cm;
 330 
 331   volatile bool        _scan_in_progress;
 332   volatile bool        _should_abort;
 333   HeapRegion* volatile _next_survivor;
 334 
 335 public:
 336   CMRootRegions();
 337   // We actually do most of the initialization in this method.
 338   void init(G1CollectedHeap* g1h, ConcurrentMark* cm);
 339 
 340   // Reset the claiming / scanning of the root regions.
 341   void prepare_for_scan();
 342 
 343   // Forces get_next() to return NULL so that the iteration aborts early.
 344   void abort() { _should_abort = true; }
 345 
 346   // Return true if the CM thread are actively scanning root regions,
 347   // false otherwise.
 348   bool scan_in_progress() { return _scan_in_progress; }
 349 
 350   // Claim the next root region to scan atomically, or return NULL if
 351   // all have been claimed.
 352   HeapRegion* claim_next();
 353 
 354   // Flag that we're done with root region scanning and notify anyone
 355   // who's waiting on it. If aborted is false, assume that all regions
 356   // have been claimed.
 357   void scan_finished();
 358 
 359   // If CM threads are still scanning root regions, wait until they
 360   // are done. Return true if we had to wait, false otherwise.
 361   bool wait_until_scan_finished();
 362 };
 363 
 364 class ConcurrentMarkThread;
 365 
 366 class ConcurrentMark: public CHeapObj<mtGC> {
 367   friend class CMMarkStack;
 368   friend class ConcurrentMarkThread;
 369   friend class CMTask;
 370   friend class CMBitMapClosure;
 371   friend class CMGlobalObjectClosure;
 372   friend class CMRemarkTask;
 373   friend class CMConcurrentMarkingTask;
 374   friend class G1ParNoteEndTask;
 375   friend class CalcLiveObjectsClosure;
 376   friend class G1CMRefProcTaskProxy;
 377   friend class G1CMRefProcTaskExecutor;
 378   friend class G1CMKeepAliveAndDrainClosure;
 379   friend class G1CMDrainMarkingStackClosure;
 380 
 381 protected:
 382   ConcurrentMarkThread* _cmThread;   // the thread doing the work
 383   G1CollectedHeap*      _g1h;        // the heap.
 384   uint                  _parallel_marking_threads; // the number of marking
 385                                                    // threads we're use
 386   uint                  _max_parallel_marking_threads; // max number of marking
 387                                                    // threads we'll ever use
 388   double                _sleep_factor; // how much we have to sleep, with
 389                                        // respect to the work we just did, to
 390                                        // meet the marking overhead goal
 391   double                _marking_task_overhead; // marking target overhead for
 392                                                 // a single task
 393 
 394   // same as the two above, but for the cleanup task
 395   double                _cleanup_sleep_factor;
 396   double                _cleanup_task_overhead;
 397 
 398   FreeRegionList        _cleanup_list;
 399 
 400   // Concurrent marking support structures
 401   CMBitMap                _markBitMap1;
 402   CMBitMap                _markBitMap2;
 403   CMBitMapRO*             _prevMarkBitMap; // completed mark bitmap
 404   CMBitMap*               _nextMarkBitMap; // under-construction mark bitmap
 405 
 406   BitMap                  _region_bm;
 407   BitMap                  _card_bm;
 408 
 409   // Heap bounds
 410   HeapWord*               _heap_start;
 411   HeapWord*               _heap_end;
 412 
 413   // Root region tracking and claiming.
 414   CMRootRegions           _root_regions;
 415 
 416   // For gray objects
 417   CMMarkStack             _markStack; // Grey objects behind global finger.
 418   HeapWord* volatile      _finger;  // the global finger, region aligned,
 419                                     // always points to the end of the
 420                                     // last claimed region
 421 
 422   // marking tasks
 423   uint                    _max_worker_id;// maximum worker id
 424   uint                    _active_tasks; // task num currently active
 425   CMTask**                _tasks;        // task queue array (max_worker_id len)
 426   CMTaskQueueSet*         _task_queues;  // task queue set
 427   ParallelTaskTerminator  _terminator;   // for termination
 428 
 429   // Two sync barriers that are used to synchronise tasks when an
 430   // overflow occurs. The algorithm is the following. All tasks enter
 431   // the first one to ensure that they have all stopped manipulating
 432   // the global data structures. After they exit it, they re-initialise
 433   // their data structures and task 0 re-initialises the global data
 434   // structures. Then, they enter the second sync barrier. This
 435   // ensure, that no task starts doing work before all data
 436   // structures (local and global) have been re-initialised. When they
 437   // exit it, they are free to start working again.
 438   WorkGangBarrierSync     _first_overflow_barrier_sync;
 439   WorkGangBarrierSync     _second_overflow_barrier_sync;
 440 
 441   // this is set by any task, when an overflow on the global data
 442   // structures is detected.
 443   volatile bool           _has_overflown;
 444   // true: marking is concurrent, false: we're in remark
 445   volatile bool           _concurrent;
 446   // set at the end of a Full GC so that marking aborts
 447   volatile bool           _has_aborted;
 448 
 449   // used when remark aborts due to an overflow to indicate that
 450   // another concurrent marking phase should start
 451   volatile bool           _restart_for_overflow;
 452 
 453   // This is true from the very start of concurrent marking until the
 454   // point when all the tasks complete their work. It is really used
 455   // to determine the points between the end of concurrent marking and
 456   // time of remark.
 457   volatile bool           _concurrent_marking_in_progress;
 458 
 459   // verbose level
 460   CMVerboseLevel          _verbose_level;
 461 
 462   // All of these times are in ms.
 463   NumberSeq _init_times;
 464   NumberSeq _remark_times;
 465   NumberSeq   _remark_mark_times;
 466   NumberSeq   _remark_weak_ref_times;
 467   NumberSeq _cleanup_times;
 468   double    _total_counting_time;
 469   double    _total_rs_scrub_time;
 470 
 471   double*   _accum_task_vtime;   // accumulated task vtime
 472 
 473   FlexibleWorkGang* _parallel_workers;
 474 
 475   ForceOverflowSettings _force_overflow_conc;
 476   ForceOverflowSettings _force_overflow_stw;
 477 
 478   void weakRefsWork(bool clear_all_soft_refs);
 479 
 480   void swapMarkBitMaps();
 481 
 482   // It resets the global marking data structures, as well as the
 483   // task local ones; should be called during initial mark.
 484   void reset();
 485 
 486   // Resets all the marking data structures. Called when we have to restart
 487   // marking or when marking completes (via set_non_marking_state below).
 488   void reset_marking_state(bool clear_overflow = true);
 489 
 490   // We do this after we're done with marking so that the marking data
 491   // structures are initialised to a sensible and predictable state.
 492   void set_non_marking_state();
 493 
 494   // It should be called to indicate which phase we're in (concurrent
 495   // mark or remark) and how many threads are currently active.
 496   void set_phase(uint active_tasks, bool concurrent);
 497 
 498   // prints all gathered CM-related statistics
 499   void print_stats();
 500 
 501   bool cleanup_list_is_empty() {
 502     return _cleanup_list.is_empty();
 503   }
 504 
 505   // accessor methods
 506   uint parallel_marking_threads() const     { return _parallel_marking_threads; }
 507   uint max_parallel_marking_threads() const { return _max_parallel_marking_threads;}
 508   double sleep_factor()                     { return _sleep_factor; }
 509   double marking_task_overhead()            { return _marking_task_overhead;}
 510   double cleanup_sleep_factor()             { return _cleanup_sleep_factor; }
 511   double cleanup_task_overhead()            { return _cleanup_task_overhead;}
 512 
 513   bool use_parallel_marking_threads() const {
 514     assert(parallel_marking_threads() <=
 515            max_parallel_marking_threads(), "sanity");
 516     assert((_parallel_workers == NULL && parallel_marking_threads() == 0) ||
 517            parallel_marking_threads() > 0,
 518            "parallel workers not set up correctly");
 519     return _parallel_workers != NULL;
 520   }
 521 
 522   HeapWord*               finger()          { return _finger;   }
 523   bool                    concurrent()      { return _concurrent; }
 524   uint                    active_tasks()    { return _active_tasks; }
 525   ParallelTaskTerminator* terminator()      { return &_terminator; }
 526 
 527   // It claims the next available region to be scanned by a marking
 528   // task/thread. It might return NULL if the next region is empty or
 529   // we have run out of regions. In the latter case, out_of_regions()
 530   // determines whether we've really run out of regions or the task
 531   // should call claim_region() again. This might seem a bit
 532   // awkward. Originally, the code was written so that claim_region()
 533   // either successfully returned with a non-empty region or there
 534   // were no more regions to be claimed. The problem with this was
 535   // that, in certain circumstances, it iterated over large chunks of
 536   // the heap finding only empty regions and, while it was working, it
 537   // was preventing the calling task to call its regular clock
 538   // method. So, this way, each task will spend very little time in
 539   // claim_region() and is allowed to call the regular clock method
 540   // frequently.
 541   HeapRegion* claim_region(uint worker_id);
 542 
 543   // It determines whether we've run out of regions to scan.
 544   bool        out_of_regions() { return _finger == _heap_end; }
 545 
 546   // Returns the task with the given id
 547   CMTask* task(int id) {
 548     assert(0 <= id && id < (int) _active_tasks,
 549            "task id not within active bounds");
 550     return _tasks[id];
 551   }
 552 
 553   // Returns the task queue with the given id
 554   CMTaskQueue* task_queue(int id) {
 555     assert(0 <= id && id < (int) _active_tasks,
 556            "task queue id not within active bounds");
 557     return (CMTaskQueue*) _task_queues->queue(id);
 558   }
 559 
 560   // Returns the task queue set
 561   CMTaskQueueSet* task_queues()  { return _task_queues; }
 562 
 563   // Access / manipulation of the overflow flag which is set to
 564   // indicate that the global stack has overflown
 565   bool has_overflown()           { return _has_overflown; }
 566   void set_has_overflown()       { _has_overflown = true; }
 567   void clear_has_overflown()     { _has_overflown = false; }
 568   bool restart_for_overflow()    { return _restart_for_overflow; }
 569 
 570   bool has_aborted()             { return _has_aborted; }
 571 
 572   // Methods to enter the two overflow sync barriers
 573   void enter_first_sync_barrier(uint worker_id);
 574   void enter_second_sync_barrier(uint worker_id);
 575 
 576   ForceOverflowSettings* force_overflow_conc() {
 577     return &_force_overflow_conc;
 578   }
 579 
 580   ForceOverflowSettings* force_overflow_stw() {
 581     return &_force_overflow_stw;
 582   }
 583 
 584   ForceOverflowSettings* force_overflow() {
 585     if (concurrent()) {
 586       return force_overflow_conc();
 587     } else {
 588       return force_overflow_stw();
 589     }
 590   }
 591 
 592   // Live Data Counting data structures...
 593   // These data structures are initialized at the start of
 594   // marking. They are written to while marking is active.
 595   // They are aggregated during remark; the aggregated values
 596   // are then used to populate the _region_bm, _card_bm, and
 597   // the total live bytes, which are then subsequently updated
 598   // during cleanup.
 599 
 600   // An array of bitmaps (one bit map per task). Each bitmap
 601   // is used to record the cards spanned by the live objects
 602   // marked by that task/worker.
 603   BitMap*  _count_card_bitmaps;
 604 
 605   // Used to record the number of marked live bytes
 606   // (for each region, by worker thread).
 607   size_t** _count_marked_bytes;
 608 
 609   // Card index of the bottom of the G1 heap. Used for biasing indices into
 610   // the card bitmaps.
 611   intptr_t _heap_bottom_card_num;
 612 
 613   // Set to true when initialization is complete
 614   bool _completed_initialization;
 615 
 616 public:
 617   // Manipulation of the global mark stack.
 618   // Notice that the first mark_stack_push is CAS-based, whereas the
 619   // two below are Mutex-based. This is OK since the first one is only
 620   // called during evacuation pauses and doesn't compete with the
 621   // other two (which are called by the marking tasks during
 622   // concurrent marking or remark).
 623   bool mark_stack_push(oop p) {
 624     _markStack.par_push(p);
 625     if (_markStack.overflow()) {
 626       set_has_overflown();
 627       return false;
 628     }
 629     return true;
 630   }
 631   bool mark_stack_push(oop* arr, int n) {
 632     _markStack.par_push_arr(arr, n);
 633     if (_markStack.overflow()) {
 634       set_has_overflown();
 635       return false;
 636     }
 637     return true;
 638   }
 639   void mark_stack_pop(oop* arr, int max, int* n) {
 640     _markStack.par_pop_arr(arr, max, n);
 641   }
 642   size_t mark_stack_size()                { return _markStack.size(); }
 643   size_t partial_mark_stack_size_target() { return _markStack.maxElems()/3; }
 644   bool mark_stack_overflow()              { return _markStack.overflow(); }
 645   bool mark_stack_empty()                 { return _markStack.isEmpty(); }
 646 
 647   CMRootRegions* root_regions() { return &_root_regions; }
 648 
 649   bool concurrent_marking_in_progress() {
 650     return _concurrent_marking_in_progress;
 651   }
 652   void set_concurrent_marking_in_progress() {
 653     _concurrent_marking_in_progress = true;
 654   }
 655   void clear_concurrent_marking_in_progress() {
 656     _concurrent_marking_in_progress = false;
 657   }
 658 
 659   void update_accum_task_vtime(int i, double vtime) {
 660     _accum_task_vtime[i] += vtime;
 661   }
 662 
 663   double all_task_accum_vtime() {
 664     double ret = 0.0;
 665     for (uint i = 0; i < _max_worker_id; ++i)
 666       ret += _accum_task_vtime[i];
 667     return ret;
 668   }
 669 
 670   // Attempts to steal an object from the task queues of other tasks
 671   bool try_stealing(uint worker_id, int* hash_seed, oop& obj) {
 672     return _task_queues->steal(worker_id, hash_seed, obj);
 673   }
 674 
 675   ConcurrentMark(G1CollectedHeap* g1h, ReservedSpace heap_rs);
 676   ~ConcurrentMark();
 677 
 678   ConcurrentMarkThread* cmThread() { return _cmThread; }
 679 
 680   CMBitMapRO* prevMarkBitMap() const { return _prevMarkBitMap; }
 681   CMBitMap*   nextMarkBitMap() const { return _nextMarkBitMap; }
 682 
 683   // Returns the number of GC threads to be used in a concurrent
 684   // phase based on the number of GC threads being used in a STW
 685   // phase.
 686   uint scale_parallel_threads(uint n_par_threads);
 687 
 688   // Calculates the number of GC threads to be used in a concurrent phase.
 689   uint calc_parallel_marking_threads();
 690 
 691   // The following three are interaction between CM and
 692   // G1CollectedHeap
 693 
 694   // This notifies CM that a root during initial-mark needs to be
 695   // grayed. It is MT-safe. word_size is the size of the object in
 696   // words. It is passed explicitly as sometimes we cannot calculate
 697   // it from the given object because it might be in an inconsistent
 698   // state (e.g., in to-space and being copied). So the caller is
 699   // responsible for dealing with this issue (e.g., get the size from
 700   // the from-space image when the to-space image might be
 701   // inconsistent) and always passing the size. hr is the region that
 702   // contains the object and it's passed optionally from callers who
 703   // might already have it (no point in recalculating it).
 704   inline void grayRoot(oop obj, size_t word_size,
 705                        uint worker_id, HeapRegion* hr = NULL);
 706 
 707   // It iterates over the heap and for each object it comes across it
 708   // will dump the contents of its reference fields, as well as
 709   // liveness information for the object and its referents. The dump
 710   // will be written to a file with the following name:
 711   // G1PrintReachableBaseFile + "." + str.
 712   // vo decides whether the prev (vo == UsePrevMarking), the next
 713   // (vo == UseNextMarking) marking information, or the mark word
 714   // (vo == UseMarkWord) will be used to determine the liveness of
 715   // each object / referent.
 716   // If all is true, all objects in the heap will be dumped, otherwise
 717   // only the live ones. In the dump the following symbols / breviations
 718   // are used:
 719   //   M : an explicitly live object (its bitmap bit is set)
 720   //   > : an implicitly live object (over tams)
 721   //   O : an object outside the G1 heap (typically: in the perm gen)
 722   //   NOT : a reference field whose referent is not live
 723   //   AND MARKED : indicates that an object is both explicitly and
 724   //   implicitly live (it should be one or the other, not both)
 725   void print_reachable(const char* str,
 726                        VerifyOption vo, bool all) PRODUCT_RETURN;
 727 
 728   // Clear the next marking bitmap (will be called concurrently).
 729   void clearNextBitmap();
 730 
 731   // These two do the work that needs to be done before and after the
 732   // initial root checkpoint. Since this checkpoint can be done at two
 733   // different points (i.e. an explicit pause or piggy-backed on a
 734   // young collection), then it's nice to be able to easily share the
 735   // pre/post code. It might be the case that we can put everything in
 736   // the post method. TP
 737   void checkpointRootsInitialPre();
 738   void checkpointRootsInitialPost();
 739 
 740   // Scan all the root regions and mark everything reachable from
 741   // them.
 742   void scanRootRegions();
 743 
 744   // Scan a single root region and mark everything reachable from it.
 745   void scanRootRegion(HeapRegion* hr, uint worker_id);
 746 
 747   // Do concurrent phase of marking, to a tentative transitive closure.
 748   void markFromRoots();
 749 
 750   void checkpointRootsFinal(bool clear_all_soft_refs);
 751   void checkpointRootsFinalWork();
 752   void cleanup();
 753   void completeCleanup();
 754 
 755   // Mark in the previous bitmap.  NB: this is usually read-only, so use
 756   // this carefully!
 757   inline void markPrev(oop p);
 758 
 759   // Clears marks for all objects in the given range, for the prev,
 760   // next, or both bitmaps.  NB: the previous bitmap is usually
 761   // read-only, so use this carefully!
 762   void clearRangePrevBitmap(MemRegion mr);
 763   void clearRangeNextBitmap(MemRegion mr);
 764   void clearRangeBothBitmaps(MemRegion mr);
 765 
 766   // Notify data structures that a GC has started.
 767   void note_start_of_gc() {
 768     _markStack.note_start_of_gc();
 769   }
 770 
 771   // Notify data structures that a GC is finished.
 772   void note_end_of_gc() {
 773     _markStack.note_end_of_gc();
 774   }
 775 
 776   // Verify that there are no CSet oops on the stacks (taskqueues /
 777   // global mark stack), enqueued SATB buffers, per-thread SATB
 778   // buffers, and fingers (global / per-task). The boolean parameters
 779   // decide which of the above data structures to verify. If marking
 780   // is not in progress, it's a no-op.
 781   void verify_no_cset_oops(bool verify_stacks,
 782                            bool verify_enqueued_buffers,
 783                            bool verify_thread_buffers,
 784                            bool verify_fingers) PRODUCT_RETURN;
 785 
 786   // It is called at the end of an evacuation pause during marking so
 787   // that CM is notified of where the new end of the heap is. It
 788   // doesn't do anything if concurrent_marking_in_progress() is false,
 789   // unless the force parameter is true.
 790   void update_g1_committed(bool force = false);
 791 
 792   bool isMarked(oop p) const {
 793     assert(p != NULL && p->is_oop(), "expected an oop");
 794     HeapWord* addr = (HeapWord*)p;
 795     assert(addr >= _nextMarkBitMap->startWord() ||
 796            addr < _nextMarkBitMap->endWord(), "in a region");
 797 
 798     return _nextMarkBitMap->isMarked(addr);
 799   }
 800 
 801   inline bool not_yet_marked(oop p) const;
 802 
 803   // XXX Debug code
 804   bool containing_card_is_marked(void* p);
 805   bool containing_cards_are_marked(void* start, void* last);
 806 
 807   bool isPrevMarked(oop p) const {
 808     assert(p != NULL && p->is_oop(), "expected an oop");
 809     HeapWord* addr = (HeapWord*)p;
 810     assert(addr >= _prevMarkBitMap->startWord() ||
 811            addr < _prevMarkBitMap->endWord(), "in a region");
 812 
 813     return _prevMarkBitMap->isMarked(addr);
 814   }
 815 
 816   inline bool do_yield_check(uint worker_i = 0);
 817   inline bool should_yield();
 818 
 819   // Called to abort the marking cycle after a Full GC takes palce.
 820   void abort();
 821 
 822   // This prints the global/local fingers. It is used for debugging.
 823   NOT_PRODUCT(void print_finger();)
 824 
 825   void print_summary_info();
 826 
 827   void print_worker_threads_on(outputStream* st) const;
 828 
 829   // The following indicate whether a given verbose level has been
 830   // set. Notice that anything above stats is conditional to
 831   // _MARKING_VERBOSE_ having been set to 1
 832   bool verbose_stats() {
 833     return _verbose_level >= stats_verbose;
 834   }
 835   bool verbose_low() {
 836     return _MARKING_VERBOSE_ && _verbose_level >= low_verbose;
 837   }
 838   bool verbose_medium() {
 839     return _MARKING_VERBOSE_ && _verbose_level >= medium_verbose;
 840   }
 841   bool verbose_high() {
 842     return _MARKING_VERBOSE_ && _verbose_level >= high_verbose;
 843   }
 844 
 845   // Liveness counting
 846 
 847   // Utility routine to set an exclusive range of cards on the given
 848   // card liveness bitmap
 849   inline void set_card_bitmap_range(BitMap* card_bm,
 850                                     BitMap::idx_t start_idx,
 851                                     BitMap::idx_t end_idx,
 852                                     bool is_par);
 853 
 854   // Returns the card number of the bottom of the G1 heap.
 855   // Used in biasing indices into accounting card bitmaps.
 856   intptr_t heap_bottom_card_num() const {
 857     return _heap_bottom_card_num;
 858   }
 859 
 860   // Returns the card bitmap for a given task or worker id.
 861   BitMap* count_card_bitmap_for(uint worker_id) {
 862     assert(0 <= worker_id && worker_id < _max_worker_id, "oob");
 863     assert(_count_card_bitmaps != NULL, "uninitialized");
 864     BitMap* task_card_bm = &_count_card_bitmaps[worker_id];
 865     assert(task_card_bm->size() == _card_bm.size(), "size mismatch");
 866     return task_card_bm;
 867   }
 868 
 869   // Returns the array containing the marked bytes for each region,
 870   // for the given worker or task id.
 871   size_t* count_marked_bytes_array_for(uint worker_id) {
 872     assert(0 <= worker_id && worker_id < _max_worker_id, "oob");
 873     assert(_count_marked_bytes != NULL, "uninitialized");
 874     size_t* marked_bytes_array = _count_marked_bytes[worker_id];
 875     assert(marked_bytes_array != NULL, "uninitialized");
 876     return marked_bytes_array;
 877   }
 878 
 879   // Returns the index in the liveness accounting card table bitmap
 880   // for the given address
 881   inline BitMap::idx_t card_bitmap_index_for(HeapWord* addr);
 882 
 883   // Counts the size of the given memory region in the the given
 884   // marked_bytes array slot for the given HeapRegion.
 885   // Sets the bits in the given card bitmap that are associated with the
 886   // cards that are spanned by the memory region.
 887   inline void count_region(MemRegion mr, HeapRegion* hr,
 888                            size_t* marked_bytes_array,
 889                            BitMap* task_card_bm);
 890 
 891   // Counts the given memory region in the task/worker counting
 892   // data structures for the given worker id.
 893   inline void count_region(MemRegion mr, HeapRegion* hr, uint worker_id);
 894 
 895   // Counts the given memory region in the task/worker counting
 896   // data structures for the given worker id.
 897   inline void count_region(MemRegion mr, uint worker_id);
 898 
 899   // Counts the given object in the given task/worker counting
 900   // data structures.
 901   inline void count_object(oop obj, HeapRegion* hr,
 902                            size_t* marked_bytes_array,
 903                            BitMap* task_card_bm);
 904 
 905   // Counts the given object in the task/worker counting data
 906   // structures for the given worker id.
 907   inline void count_object(oop obj, HeapRegion* hr, uint worker_id);
 908 
 909   // Attempts to mark the given object and, if successful, counts
 910   // the object in the given task/worker counting structures.
 911   inline bool par_mark_and_count(oop obj, HeapRegion* hr,
 912                                  size_t* marked_bytes_array,
 913                                  BitMap* task_card_bm);
 914 
 915   // Attempts to mark the given object and, if successful, counts
 916   // the object in the task/worker counting structures for the
 917   // given worker id.
 918   inline bool par_mark_and_count(oop obj, size_t word_size,
 919                                  HeapRegion* hr, uint worker_id);
 920 
 921   // Attempts to mark the given object and, if successful, counts
 922   // the object in the task/worker counting structures for the
 923   // given worker id.
 924   inline bool par_mark_and_count(oop obj, HeapRegion* hr, uint worker_id);
 925 
 926   // Similar to the above routine but we don't know the heap region that
 927   // contains the object to be marked/counted, which this routine looks up.
 928   inline bool par_mark_and_count(oop obj, uint worker_id);
 929 
 930   // Similar to the above routine but there are times when we cannot
 931   // safely calculate the size of obj due to races and we, therefore,
 932   // pass the size in as a parameter. It is the caller's reponsibility
 933   // to ensure that the size passed in for obj is valid.
 934   inline bool par_mark_and_count(oop obj, size_t word_size, uint worker_id);
 935 
 936   // Unconditionally mark the given object, and unconditinally count
 937   // the object in the counting structures for worker id 0.
 938   // Should *not* be called from parallel code.
 939   inline bool mark_and_count(oop obj, HeapRegion* hr);
 940 
 941   // Similar to the above routine but we don't know the heap region that
 942   // contains the object to be marked/counted, which this routine looks up.
 943   // Should *not* be called from parallel code.
 944   inline bool mark_and_count(oop obj);
 945 
 946   // Returns true if initialization was successfully completed.
 947   bool completed_initialization() const {
 948     return _completed_initialization;
 949   }
 950 
 951 protected:
 952   // Clear all the per-task bitmaps and arrays used to store the
 953   // counting data.
 954   void clear_all_count_data();
 955 
 956   // Aggregates the counting data for each worker/task
 957   // that was constructed while marking. Also sets
 958   // the amount of marked bytes for each region and
 959   // the top at concurrent mark count.
 960   void aggregate_count_data();
 961 
 962   // Verification routine
 963   void verify_count_data();
 964 };
 965 
 966 // A class representing a marking task.
 967 class CMTask : public TerminatorTerminator {
 968 private:
 969   enum PrivateConstants {
 970     // the regular clock call is called once the scanned words reaches
 971     // this limit
 972     words_scanned_period          = 12*1024,
 973     // the regular clock call is called once the number of visited
 974     // references reaches this limit
 975     refs_reached_period           = 384,
 976     // initial value for the hash seed, used in the work stealing code
 977     init_hash_seed                = 17,
 978     // how many entries will be transferred between global stack and
 979     // local queues
 980     global_stack_transfer_size    = 16
 981   };
 982 
 983   uint                        _worker_id;
 984   G1CollectedHeap*            _g1h;
 985   ConcurrentMark*             _cm;
 986   CMBitMap*                   _nextMarkBitMap;
 987   // the task queue of this task
 988   CMTaskQueue*                _task_queue;
 989 private:
 990   // the task queue set---needed for stealing
 991   CMTaskQueueSet*             _task_queues;
 992   // indicates whether the task has been claimed---this is only  for
 993   // debugging purposes
 994   bool                        _claimed;
 995 
 996   // number of calls to this task
 997   int                         _calls;
 998 
 999   // when the virtual timer reaches this time, the marking step should
1000   // exit
1001   double                      _time_target_ms;
1002   // the start time of the current marking step
1003   double                      _start_time_ms;
1004 
1005   // the oop closure used for iterations over oops
1006   G1CMOopClosure*             _cm_oop_closure;
1007 
1008   // the region this task is scanning, NULL if we're not scanning any
1009   HeapRegion*                 _curr_region;
1010   // the local finger of this task, NULL if we're not scanning a region
1011   HeapWord*                   _finger;
1012   // limit of the region this task is scanning, NULL if we're not scanning one
1013   HeapWord*                   _region_limit;
1014 
1015   // the number of words this task has scanned
1016   size_t                      _words_scanned;
1017   // When _words_scanned reaches this limit, the regular clock is
1018   // called. Notice that this might be decreased under certain
1019   // circumstances (i.e. when we believe that we did an expensive
1020   // operation).
1021   size_t                      _words_scanned_limit;
1022   // the initial value of _words_scanned_limit (i.e. what it was
1023   // before it was decreased).
1024   size_t                      _real_words_scanned_limit;
1025 
1026   // the number of references this task has visited
1027   size_t                      _refs_reached;
1028   // When _refs_reached reaches this limit, the regular clock is
1029   // called. Notice this this might be decreased under certain
1030   // circumstances (i.e. when we believe that we did an expensive
1031   // operation).
1032   size_t                      _refs_reached_limit;
1033   // the initial value of _refs_reached_limit (i.e. what it was before
1034   // it was decreased).
1035   size_t                      _real_refs_reached_limit;
1036 
1037   // used by the work stealing stuff
1038   int                         _hash_seed;
1039   // if this is true, then the task has aborted for some reason
1040   bool                        _has_aborted;
1041   // set when the task aborts because it has met its time quota
1042   bool                        _has_timed_out;
1043   // true when we're draining SATB buffers; this avoids the task
1044   // aborting due to SATB buffers being available (as we're already
1045   // dealing with them)
1046   bool                        _draining_satb_buffers;
1047 
1048   // number sequence of past step times
1049   NumberSeq                   _step_times_ms;
1050   // elapsed time of this task
1051   double                      _elapsed_time_ms;
1052   // termination time of this task
1053   double                      _termination_time_ms;
1054   // when this task got into the termination protocol
1055   double                      _termination_start_time_ms;
1056 
1057   // true when the task is during a concurrent phase, false when it is
1058   // in the remark phase (so, in the latter case, we do not have to
1059   // check all the things that we have to check during the concurrent
1060   // phase, i.e. SATB buffer availability...)
1061   bool                        _concurrent;
1062 
1063   TruncatedSeq                _marking_step_diffs_ms;
1064 
1065   // Counting data structures. Embedding the task's marked_bytes_array
1066   // and card bitmap into the actual task saves having to go through
1067   // the ConcurrentMark object.
1068   size_t*                     _marked_bytes_array;
1069   BitMap*                     _card_bm;
1070 
1071   // LOTS of statistics related with this task
1072 #if _MARKING_STATS_
1073   NumberSeq                   _all_clock_intervals_ms;
1074   double                      _interval_start_time_ms;
1075 
1076   int                         _aborted;
1077   int                         _aborted_overflow;
1078   int                         _aborted_cm_aborted;
1079   int                         _aborted_yield;
1080   int                         _aborted_timed_out;
1081   int                         _aborted_satb;
1082   int                         _aborted_termination;
1083 
1084   int                         _steal_attempts;
1085   int                         _steals;
1086 
1087   int                         _clock_due_to_marking;
1088   int                         _clock_due_to_scanning;
1089 
1090   int                         _local_pushes;
1091   int                         _local_pops;
1092   int                         _local_max_size;
1093   int                         _objs_scanned;
1094 
1095   int                         _global_pushes;
1096   int                         _global_pops;
1097   int                         _global_max_size;
1098 
1099   int                         _global_transfers_to;
1100   int                         _global_transfers_from;
1101 
1102   int                         _regions_claimed;
1103   int                         _objs_found_on_bitmap;
1104 
1105   int                         _satb_buffers_processed;
1106 #endif // _MARKING_STATS_
1107 
1108   // it updates the local fields after this task has claimed
1109   // a new region to scan
1110   void setup_for_region(HeapRegion* hr);
1111   // it brings up-to-date the limit of the region
1112   void update_region_limit();
1113 
1114   // called when either the words scanned or the refs visited limit
1115   // has been reached
1116   void reached_limit();
1117   // recalculates the words scanned and refs visited limits
1118   void recalculate_limits();
1119   // decreases the words scanned and refs visited limits when we reach
1120   // an expensive operation
1121   void decrease_limits();
1122   // it checks whether the words scanned or refs visited reached their
1123   // respective limit and calls reached_limit() if they have
1124   void check_limits() {
1125     if (_words_scanned >= _words_scanned_limit ||
1126         _refs_reached >= _refs_reached_limit) {
1127       reached_limit();
1128     }
1129   }
1130   // this is supposed to be called regularly during a marking step as
1131   // it checks a bunch of conditions that might cause the marking step
1132   // to abort
1133   void regular_clock_call();
1134   bool concurrent() { return _concurrent; }
1135 
1136 public:
1137   // It resets the task; it should be called right at the beginning of
1138   // a marking phase.
1139   void reset(CMBitMap* _nextMarkBitMap);
1140   // it clears all the fields that correspond to a claimed region.
1141   void clear_region_fields();
1142 
1143   void set_concurrent(bool concurrent) { _concurrent = concurrent; }
1144 
1145   // The main method of this class which performs a marking step
1146   // trying not to exceed the given duration. However, it might exit
1147   // prematurely, according to some conditions (i.e. SATB buffers are
1148   // available for processing).
1149   void do_marking_step(double target_ms,
1150                        bool do_stealing,
1151                        bool do_termination,
1152                        bool is_serial);
1153 
1154   // These two calls start and stop the timer
1155   void record_start_time() {
1156     _elapsed_time_ms = os::elapsedTime() * 1000.0;
1157   }
1158   void record_end_time() {
1159     _elapsed_time_ms = os::elapsedTime() * 1000.0 - _elapsed_time_ms;
1160   }
1161 
1162   // returns the worker ID associated with this task.
1163   uint worker_id() { return _worker_id; }
1164 
1165   // From TerminatorTerminator. It determines whether this task should
1166   // exit the termination protocol after it's entered it.
1167   virtual bool should_exit_termination();
1168 
1169   // Resets the local region fields after a task has finished scanning a
1170   // region; or when they have become stale as a result of the region
1171   // being evacuated.
1172   void giveup_current_region();
1173 
1174   HeapWord* finger()            { return _finger; }
1175 
1176   bool has_aborted()            { return _has_aborted; }
1177   void set_has_aborted()        { _has_aborted = true; }
1178   void clear_has_aborted()      { _has_aborted = false; }
1179   bool has_timed_out()          { return _has_timed_out; }
1180   bool claimed()                { return _claimed; }
1181 
1182   void set_cm_oop_closure(G1CMOopClosure* cm_oop_closure);
1183 
1184   // It grays the object by marking it and, if necessary, pushing it
1185   // on the local queue
1186   inline void deal_with_reference(oop obj);
1187 
1188   // It scans an object and visits its children.
1189   void scan_object(oop obj);
1190 
1191   // It pushes an object on the local queue.
1192   inline void push(oop obj);
1193 
1194   // These two move entries to/from the global stack.
1195   void move_entries_to_global_stack();
1196   void get_entries_from_global_stack();
1197 
1198   // It pops and scans objects from the local queue. If partially is
1199   // true, then it stops when the queue size is of a given limit. If
1200   // partially is false, then it stops when the queue is empty.
1201   void drain_local_queue(bool partially);
1202   // It moves entries from the global stack to the local queue and
1203   // drains the local queue. If partially is true, then it stops when
1204   // both the global stack and the local queue reach a given size. If
1205   // partially if false, it tries to empty them totally.
1206   void drain_global_stack(bool partially);
1207   // It keeps picking SATB buffers and processing them until no SATB
1208   // buffers are available.
1209   void drain_satb_buffers();
1210 
1211   // moves the local finger to a new location
1212   inline void move_finger_to(HeapWord* new_finger) {
1213     assert(new_finger >= _finger && new_finger < _region_limit, "invariant");
1214     _finger = new_finger;
1215   }
1216 
1217   CMTask(uint worker_id, ConcurrentMark *cm,
1218          size_t* marked_bytes, BitMap* card_bm,
1219          CMTaskQueue* task_queue, CMTaskQueueSet* task_queues);
1220 
1221   // it prints statistics associated with this task
1222   void print_stats();
1223 
1224 #if _MARKING_STATS_
1225   void increase_objs_found_on_bitmap() { ++_objs_found_on_bitmap; }
1226 #endif // _MARKING_STATS_
1227 };
1228 
1229 // Class that's used to to print out per-region liveness
1230 // information. It's currently used at the end of marking and also
1231 // after we sort the old regions at the end of the cleanup operation.
1232 class G1PrintRegionLivenessInfoClosure: public HeapRegionClosure {
1233 private:
1234   outputStream* _out;
1235 
1236   // Accumulators for these values.
1237   size_t _total_used_bytes;
1238   size_t _total_capacity_bytes;
1239   size_t _total_prev_live_bytes;
1240   size_t _total_next_live_bytes;
1241 
1242   // These are set up when we come across a "stars humongous" region
1243   // (as this is where most of this information is stored, not in the
1244   // subsequent "continues humongous" regions). After that, for every
1245   // region in a given humongous region series we deduce the right
1246   // values for it by simply subtracting the appropriate amount from
1247   // these fields. All these values should reach 0 after we've visited
1248   // the last region in the series.
1249   size_t _hum_used_bytes;
1250   size_t _hum_capacity_bytes;
1251   size_t _hum_prev_live_bytes;
1252   size_t _hum_next_live_bytes;
1253 
1254   static double perc(size_t val, size_t total) {
1255     if (total == 0) {
1256       return 0.0;
1257     } else {
1258       return 100.0 * ((double) val / (double) total);
1259     }
1260   }
1261 
1262   static double bytes_to_mb(size_t val) {
1263     return (double) val / (double) M;
1264   }
1265 
1266   // See the .cpp file.
1267   size_t get_hum_bytes(size_t* hum_bytes);
1268   void get_hum_bytes(size_t* used_bytes, size_t* capacity_bytes,
1269                      size_t* prev_live_bytes, size_t* next_live_bytes);
1270 
1271 public:
1272   // The header and footer are printed in the constructor and
1273   // destructor respectively.
1274   G1PrintRegionLivenessInfoClosure(outputStream* out, const char* phase_name);
1275   virtual bool doHeapRegion(HeapRegion* r);
1276   ~G1PrintRegionLivenessInfoClosure();
1277 };
1278 
1279 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_CONCURRENTMARK_HPP