6484965: G1: piggy-back liveness accounting phase on marking

Summary: Remove the separate counting phase of concurrent marking by tracking the amount of marked bytes and the cards spanned by marked objects in marking task/worker thread local data structures, which are updated as individual objects are marked.
Reviewed-by: brutisso, tonyp

hotspot/src/share/vm/gc_implementation/g1/concurrentMark.hpp

@@ -426,7 +426,6 @@ protected:
   WorkGangBarrierSync     _first_overflow_barrier_sync;
   WorkGangBarrierSync     _second_overflow_barrier_sync;
 
-
   // this is set by any task, when an overflow on the global data
   // structures is detected.
   volatile bool           _has_overflown;
@@ -578,6 +577,27 @@ protected:
     }
   }
 
+  // Live Data Counting data structures...
+  // These data structures are initialized at the start of
+  // marking. They are written to while marking is active.
+  // They are aggregated during remark; the aggregated values
+  // are then used to populate the _region_bm, _card_bm, and
+  // the total live bytes, which are then subsequently updated
+  // during cleanup.
+
+  // An array of bitmaps (one bit map per task). Each bitmap
+  // is used to record the cards spanned by the live objects
+  // marked by that task/worker.
+  BitMap*  _count_card_bitmaps;
+
+  // Used to record the number of marked live bytes
+  // (for each region, by worker thread).
+  size_t** _count_marked_bytes;
+
+  // Card index of the bottom of the G1 heap. Used for biasing indices into
+  // the card bitmaps.
+  intptr_t _heap_bottom_card_num;
+
 public:
   // Manipulation of the global mark stack.
   // Notice that the first mark_stack_push is CAS-based, whereas the
@@ -703,6 +723,7 @@ public:
 
   ConcurrentMark(ReservedSpace rs, int max_regions);
   ~ConcurrentMark();
+
   ConcurrentMarkThread* cmThread() { return _cmThread; }
 
   CMBitMapRO* prevMarkBitMap() const { return _prevMarkBitMap; }
@@ -721,7 +742,7 @@ public:
 
   // This notifies CM that a root during initial-mark needs to be
   // grayed. It is MT-safe.
-  inline void grayRoot(oop obj, size_t word_size);
+  inline void grayRoot(oop obj, size_t word_size, uint worker_id);
 
   // It's used during evacuation pauses to gray a region, if
   // necessary, and it's MT-safe. It assumes that the caller has
@@ -781,15 +802,13 @@ public:
 
   void checkpointRootsFinal(bool clear_all_soft_refs);
   void checkpointRootsFinalWork();
-  void calcDesiredRegions();
   void cleanup();
   void completeCleanup();
 
   // Mark in the previous bitmap.  NB: this is usually read-only, so use
   // this carefully!
   inline void markPrev(oop p);
-  inline void markNext(oop p);
-  void clear(oop p);
+
   // Clears marks for all objects in the given range, for the prev,
   // next, or both bitmaps.  NB: the previous bitmap is usually
   // read-only, so use this carefully!
@@ -913,6 +932,104 @@ public:
   bool verbose_high() {
     return _MARKING_VERBOSE_ && _verbose_level >= high_verbose;
   }
+
+  // Counting data structure accessors
+
+  // Returns the card number of the bottom of the G1 heap.
+  // Used in biasing indices into accounting card bitmaps.
+  intptr_t heap_bottom_card_num() const {
+    return _heap_bottom_card_num;
+  }
+
+  // Returns the card bitmap for a given task or worker id.
+  BitMap* count_card_bitmap_for(uint worker_id) {
+    assert(0 <= worker_id && worker_id < _max_task_num, "oob");
+    assert(_count_card_bitmaps != NULL, "uninitialized");
+    BitMap* task_card_bm = &_count_card_bitmaps[worker_id];
+    assert(task_card_bm->size() == _card_bm.size(), "size mismatch");
+    return task_card_bm;
+  }
+
+  // Returns the array containing the marked bytes for each region,
+  // for the given worker or task id.
+  size_t* count_marked_bytes_array_for(uint worker_id) {
+    assert(0 <= worker_id && worker_id < _max_task_num, "oob");
+    assert(_count_marked_bytes != NULL, "uninitialized");
+    size_t* marked_bytes_array = _count_marked_bytes[worker_id];
+    assert(marked_bytes_array != NULL, "uninitialized");
+    return marked_bytes_array;
+  }
+
+  // Returns the index in the liveness accounting card table bitmap
+  // for the given address
+  inline BitMap::idx_t card_bitmap_index_for(HeapWord* addr);
+
+  // Counts the size of the given memory region in the the given
+  // marked_bytes array slot for the given HeapRegion.
+  // Sets the bits in the given card bitmap that are associated with the
+  // cards that are spanned by the memory region.
+  inline void count_region(MemRegion mr, HeapRegion* hr,
+                           size_t* marked_bytes_array,
+                           BitMap* task_card_bm);
+
+  // Counts the given memory region in the task/worker counting
+  // data structures for the given worker id.
+  inline void count_region(MemRegion mr, uint worker_id);
+
+  // Counts the given object in the given task/worker counting
+  // data structures.
+  inline void count_object(oop obj, HeapRegion* hr,
+                           size_t* marked_bytes_array,
+                           BitMap* task_card_bm);
+
+  // Counts the given object in the task/worker counting data
+  // structures for the given worker id.
+  inline void count_object(oop obj, HeapRegion* hr, uint worker_id);
+
+  // Attempts to mark the given object and, if successful, counts
+  // the object in the given task/worker counting structures.
+  inline bool par_mark_and_count(oop obj, HeapRegion* hr,
+                                 size_t* marked_bytes_array,
+                                 BitMap* task_card_bm);
+
+  // Attempts to mark the given object and, if successful, counts
+  // the object in the task/worker counting structures for the
+  // given worker id.
+  inline bool par_mark_and_count(oop obj, HeapRegion* hr, uint worker_id);
+
+  // Similar to the above routine but we don't know the heap region that
+  // contains the object to be marked/counted, which this routine looks up.
+  inline bool par_mark_and_count(oop obj, uint worker_id);
+
+  // Similar to the above routine but there are times when we cannot
+  // safely calculate the size of obj due to races and we, therefore,
+  // pass the size in as a parameter. It is the caller's reponsibility
+  // to ensure that the size passed in for obj is valid.
+  inline bool par_mark_and_count(oop obj, size_t word_size, uint worker_id);
+
+  // Unconditionally mark the given object, and unconditinally count
+  // the object in the counting structures for worker id 0.
+  // Should *not* be called from parallel code.
+  inline bool mark_and_count(oop obj, HeapRegion* hr);
+
+  // Similar to the above routine but we don't know the heap region that
+  // contains the object to be marked/counted, which this routine looks up.
+  // Should *not* be called from parallel code.
+  inline bool mark_and_count(oop obj);
+
+protected:
+  // Clear all the per-task bitmaps and arrays used to store the
+  // counting data.
+  void clear_all_count_data();
+
+  // Aggregates the counting data for each worker/task
+  // that was constructed while marking. Also sets
+  // the amount of marked bytes for each region and
+  // the top at concurrent mark count.
+  void aggregate_count_data();
+
+  // Verification routine
+  void verify_count_data();
 };
 
 // A class representing a marking task.
@@ -1031,6 +1148,12 @@ private:
 
   TruncatedSeq                _marking_step_diffs_ms;
 
+  // Counting data structures. Embedding the task's marked_bytes_array
+  // and card bitmap into the actual task saves having to go through
+  // the ConcurrentMark object.
+  size_t*                     _marked_bytes_array;
+  BitMap*                     _card_bm;
+
   // LOTS of statistics related with this task
 #if _MARKING_STATS_
   NumberSeq                   _all_clock_intervals_ms;
@@ -1196,6 +1319,7 @@ public:
   }
 
   CMTask(int task_num, ConcurrentMark *cm,
+         size_t* marked_bytes, BitMap* card_bm,
          CMTaskQueue* task_queue, CMTaskQueueSet* task_queues);
 
   // it prints statistics associated with this task

hotspot/src/share/vm/gc_implementation/g1/concurrentMark.inline.hpp

@@ -28,6 +28,159 @@
 #include "gc_implementation/g1/concurrentMark.hpp"
 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
 
+// Returns the index in the liveness accounting card bitmap
+// for the given address
+inline BitMap::idx_t ConcurrentMark::card_bitmap_index_for(HeapWord* addr) {
+  // Below, the term "card num" means the result of shifting an address
+  // by the card shift -- address 0 corresponds to card number 0.  One
+  // must subtract the card num of the bottom of the heap to obtain a
+  // card table index.
+
+  intptr_t card_num = intptr_t(uintptr_t(addr) >> CardTableModRefBS::card_shift);
+  return card_num - heap_bottom_card_num();
+}
+
+// Counts the given memory region in the given task/worker
+// counting data structures.
+inline void ConcurrentMark::count_region(MemRegion mr, HeapRegion* hr,
+                                         size_t* marked_bytes_array,
+                                         BitMap* task_card_bm) {
+  G1CollectedHeap* g1h = _g1h;
+  HeapWord* start = mr.start();
+  HeapWord* last = mr.last();
+  size_t region_size_bytes = mr.byte_size();
+  size_t index = hr->hrs_index();
+
+  assert(!hr->continuesHumongous(), "should not be HC region");
+  assert(hr == g1h->heap_region_containing(start), "sanity");
+  assert(hr == g1h->heap_region_containing(mr.last()), "sanity");
+  assert(marked_bytes_array != NULL, "pre-condition");
+  assert(task_card_bm != NULL, "pre-condition");
+
+  // Add to the task local marked bytes for this region.
+  marked_bytes_array[index] += region_size_bytes;
+
+  BitMap::idx_t start_idx = card_bitmap_index_for(start);
+  BitMap::idx_t last_idx = card_bitmap_index_for(last);
+
+  // The card bitmap is task/worker specific => no need to use 'par' routines.
+  // Set bits in the inclusive bit range [start_idx, last_idx].
+  //
+  // For small ranges use a simple loop; otherwise use set_range
+  // The range are the cards that are spanned by the object/region
+  // so 8 cards will allow objects/regions up to 4K to be handled
+  // using the loop.
+  if ((last_idx - start_idx) <= 8) {
+    for (BitMap::idx_t i = start_idx; i <= last_idx; i += 1) {
+     task_card_bm->set_bit(i);
+    }
+  } else {
+    assert(last_idx < task_card_bm->size(), "sanity");
+    // Note: BitMap::set_range() is exclusive.
+    task_card_bm->set_range(start_idx, last_idx+1);
+  }
+}
+
+// Counts the given memory region, which may be a single object, in the
+// task/worker counting data structures for the given worker id.
+inline void ConcurrentMark::count_region(MemRegion mr, uint worker_id) {
+  size_t* marked_bytes_array = count_marked_bytes_array_for(worker_id);
+  BitMap* task_card_bm = count_card_bitmap_for(worker_id);
+  HeapWord* addr = mr.start();
+  HeapRegion* hr = _g1h->heap_region_containing_raw(addr);
+  count_region(mr, hr, marked_bytes_array, task_card_bm);
+}
+
+// Counts the given object in the given task/worker counting data structures.
+inline void ConcurrentMark::count_object(oop obj,
+                                         HeapRegion* hr,
+                                         size_t* marked_bytes_array,
+                                         BitMap* task_card_bm) {
+  MemRegion mr((HeapWord*)obj, obj->size());
+  count_region(mr, hr, marked_bytes_array, task_card_bm);
+}
+
+// Counts the given object in the task/worker counting data
+// structures for the given worker id.
+inline void ConcurrentMark::count_object(oop obj, HeapRegion* hr, uint worker_id) {
+  size_t* marked_bytes_array = count_marked_bytes_array_for(worker_id);
+  BitMap* task_card_bm = count_card_bitmap_for(worker_id);
+  HeapWord* addr = (HeapWord*) obj;
+  count_object(obj, hr, marked_bytes_array, task_card_bm);
+}
+
+// Attempts to mark the given object and, if successful, counts
+// the object in the given task/worker counting structures.
+inline bool ConcurrentMark::par_mark_and_count(oop obj,
+                                               HeapRegion* hr,
+                                               size_t* marked_bytes_array,
+                                               BitMap* task_card_bm) {
+  HeapWord* addr = (HeapWord*)obj;
+  if (_nextMarkBitMap->parMark(addr)) {
+    // Update the task specific count data for the object.
+    count_object(obj, hr, marked_bytes_array, task_card_bm);
+    return true;
+  }
+  return false;
+}
+
+// Attempts to mark the given object and, if successful, counts
+// the object in the task/worker counting structures for the
+// given worker id.
+inline bool ConcurrentMark::par_mark_and_count(oop obj,
+                                               HeapRegion* hr,
+                                               uint worker_id) {
+  HeapWord* addr = (HeapWord*)obj;
+  if (_nextMarkBitMap->parMark(addr)) {
+    // Update the task specific count data for the object.
+    count_object(obj, hr, worker_id);
+    return true;
+  }
+  return false;
+}
+
+// As above - but we don't know the heap region containing the
+// object and so have to supply it.
+inline bool ConcurrentMark::par_mark_and_count(oop obj, uint worker_id) {
+  HeapWord* addr = (HeapWord*)obj;
+  HeapRegion* hr = _g1h->heap_region_containing_raw(addr);
+  return par_mark_and_count(obj, hr, worker_id);
+}
+
+// Similar to the above routine but we already know the size, in words, of
+// the object that we wish to mark/count
+inline bool ConcurrentMark::par_mark_and_count(oop obj,
+                                               size_t word_size,
+                                               uint worker_id) {
+  HeapWord* addr = (HeapWord*)obj;
+  if (_nextMarkBitMap->parMark(addr)) {
+    // Update the task specific count data for the object.
+    MemRegion mr(addr, word_size);
+    count_region(mr, worker_id);
+    return true;
+  }
+  return false;
+}
+
+// Unconditionally mark the given object, and unconditinally count
+// the object in the counting structures for worker id 0.
+// Should *not* be called from parallel code.
+inline bool ConcurrentMark::mark_and_count(oop obj, HeapRegion* hr) {
+  HeapWord* addr = (HeapWord*)obj;
+  _nextMarkBitMap->mark(addr);
+  // Update the task specific count data for the object.
+  count_object(obj, hr, 0 /* worker_id */);
+  return true;
+}
+
+// As above - but we don't have the heap region containing the
+// object, so we have to supply it.
+inline bool ConcurrentMark::mark_and_count(oop obj) {
+  HeapWord* addr = (HeapWord*)obj;
+  HeapRegion* hr = _g1h->heap_region_containing_raw(addr);
+  return mark_and_count(obj, hr);
+}
+
 inline bool CMBitMapRO::iterate(BitMapClosure* cl, MemRegion mr) {
   HeapWord* start_addr = MAX2(startWord(), mr.start());
   HeapWord* end_addr = MIN2(endWord(), mr.end());
@@ -113,7 +266,7 @@ inline void CMTask::deal_with_reference(oop obj) {
 
   HeapWord* objAddr = (HeapWord*) obj;
   assert(obj->is_oop_or_null(true /* ignore mark word */), "Error");
- if (_g1h->is_in_g1_reserved(objAddr)) {
+  if (_g1h->is_in_g1_reserved(objAddr)) {
     assert(obj != NULL, "null check is implicit");
     if (!_nextMarkBitMap->isMarked(objAddr)) {
       // Only get the containing region if the object is not marked on the
@@ -127,9 +280,9 @@ inline void CMTask::deal_with_reference(oop obj) {
         }
 
         // we need to mark it first
-        if (_nextMarkBitMap->parMark(objAddr)) {
+        if (_cm->par_mark_and_count(obj, hr, _marked_bytes_array, _card_bm)) {
           // No OrderAccess:store_load() is needed. It is implicit in the
-          // CAS done in parMark(objAddr) above
+          // CAS done in CMBitMap::parMark() call in the routine above.
           HeapWord* global_finger = _cm->finger();
 
 #if _CHECK_BOTH_FINGERS_
@@ -189,12 +342,7 @@ inline void ConcurrentMark::markPrev(oop p) {
   ((CMBitMap*)_prevMarkBitMap)->mark((HeapWord*) p);
 }
 
-inline void ConcurrentMark::markNext(oop p) {
-  assert(!_nextMarkBitMap->isMarked((HeapWord*) p), "sanity");
-  _nextMarkBitMap->mark((HeapWord*) p);
-}
-
-inline void ConcurrentMark::grayRoot(oop obj, size_t word_size) {
+inline void ConcurrentMark::grayRoot(oop obj, size_t word_size, uint worker_id) {
   HeapWord* addr = (HeapWord*) obj;
 
   // Currently we don't do anything with word_size but we will use it
@@ -220,7 +368,7 @@ inline void ConcurrentMark::grayRoot(oop obj, size_t word_size) {
 #endif // ASSERT
 
   if (!_nextMarkBitMap->isMarked(addr)) {
-    _nextMarkBitMap->parMark(addr);
+    par_mark_and_count(obj, word_size, worker_id);
   }
 }
 

hotspot/src/share/vm/gc_implementation/g1/concurrentMarkThread.cpp

 /*
- * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -44,9 +44,7 @@ ConcurrentMarkThread::ConcurrentMarkThread(ConcurrentMark* cm) :
   _started(false),
   _in_progress(false),
   _vtime_accum(0.0),
-  _vtime_mark_accum(0.0),
-  _vtime_count_accum(0.0)
-{
+  _vtime_mark_accum(0.0) {
   create_and_start();
 }
 
@@ -148,36 +146,12 @@ void ConcurrentMarkThread::run() {
         }
       } while (cm()->restart_for_overflow());
 
-      double counting_start_time = os::elapsedVTime();
-      if (!cm()->has_aborted()) {
-        double count_start_sec = os::elapsedTime();
-        if (PrintGC) {
-          gclog_or_tty->date_stamp(PrintGCDateStamps);
-          gclog_or_tty->stamp(PrintGCTimeStamps);
-          gclog_or_tty->print_cr("[GC concurrent-count-start]");
-        }
-
-        _sts.join();
-        _cm->calcDesiredRegions();
-        _sts.leave();
-
-        if (!cm()->has_aborted()) {
-          double count_end_sec = os::elapsedTime();
-          if (PrintGC) {
-            gclog_or_tty->date_stamp(PrintGCDateStamps);
-            gclog_or_tty->stamp(PrintGCTimeStamps);
-            gclog_or_tty->print_cr("[GC concurrent-count-end, %1.7lf]",
-                                   count_end_sec - count_start_sec);
-          }
-        }
-      }
-
       double end_time = os::elapsedVTime();
-      _vtime_count_accum += (end_time - counting_start_time);
       // Update the total virtual time before doing this, since it will try
       // to measure it to get the vtime for this marking.  We purposely
       // neglect the presumably-short "completeCleanup" phase here.
       _vtime_accum = (end_time - _vtime_start);
+
       if (!cm()->has_aborted()) {
         if (g1_policy->adaptive_young_list_length()) {
           double now = os::elapsedTime();

hotspot/src/share/vm/gc_implementation/g1/concurrentMarkThread.hpp

 /*
- * Copyright (c) 2001, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2012, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -40,7 +40,6 @@ class ConcurrentMarkThread: public ConcurrentGCThread {
   double _vtime_accum;  // Accumulated virtual time.
 
   double _vtime_mark_accum;
-  double _vtime_count_accum;
 
  public:
   virtual void run();
@@ -69,8 +68,6 @@ class ConcurrentMarkThread: public ConcurrentGCThread {
   double vtime_accum();
   // Marking virtual time so far
   double vtime_mark_accum();
-  // Counting virtual time so far.
-  double vtime_count_accum() { return _vtime_count_accum; }
 
   ConcurrentMark* cm()     { return _cm; }
 

hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp

@@ -4200,7 +4200,7 @@ HeapWord* G1CollectedHeap::par_allocate_during_gc(GCAllocPurpose purpose,
 G1ParGCAllocBuffer::G1ParGCAllocBuffer(size_t gclab_word_size) :
   ParGCAllocBuffer(gclab_word_size), _retired(false) { }
 
-G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num)
+G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num)
   : _g1h(g1h),
     _refs(g1h->task_queue(queue_num)),
     _dcq(&g1h->dirty_card_queue_set()),
@@ -4321,6 +4321,7 @@ G1ParClosureSuper::G1ParClosureSuper(G1CollectedHeap* g1,
                                      G1ParScanThreadState* par_scan_state) :
   _g1(g1), _g1_rem(_g1->g1_rem_set()), _cm(_g1->concurrent_mark()),
   _par_scan_state(par_scan_state),
+  _worker_id(par_scan_state->queue_num()),
   _during_initial_mark(_g1->g1_policy()->during_initial_mark_pause()),
   _mark_in_progress(_g1->mark_in_progress()) { }
 
@@ -4332,7 +4333,7 @@ void G1ParCopyHelper::mark_object(oop obj) {
 #endif // ASSERT
 
   // We know that the object is not moving so it's safe to read its size.
-  _cm->grayRoot(obj, (size_t) obj->size());
+  _cm->grayRoot(obj, (size_t) obj->size(), _worker_id);
 }
 
 void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
@@ -4354,7 +4355,7 @@ void G1ParCopyHelper::mark_forwarded_object(oop from_obj, oop to_obj) {
   // worker so we cannot trust that its to-space image is
   // well-formed. So we have to read its size from its from-space
   // image which we know should not be changing.
-  _cm->grayRoot(to_obj, (size_t) from_obj->size());
+  _cm->grayRoot(to_obj, (size_t) from_obj->size(), _worker_id);
 }
 
 oop G1ParCopyHelper::copy_to_survivor_space(oop old) {
@@ -4444,6 +4445,8 @@ void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
   assert(barrier != G1BarrierRS || obj != NULL,
          "Precondition: G1BarrierRS implies obj is non-NULL");
 
+  assert(_worker_id == _par_scan_state->queue_num(), "sanity");
+
   // here the null check is implicit in the cset_fast_test() test
   if (_g1->in_cset_fast_test(obj)) {
     oop forwardee;
@@ -4462,7 +4465,7 @@ void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
 
     // When scanning the RS, we only care about objs in CS.
     if (barrier == G1BarrierRS) {
-      _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
+      _par_scan_state->update_rs(_from, p, _worker_id);
     }
   } else {
     // The object is not in collection set. If we're a root scanning
@@ -4474,7 +4477,7 @@ void G1ParCopyClosure<do_gen_barrier, barrier, do_mark_object>
   }
 
   if (barrier == G1BarrierEvac && obj != NULL) {
-    _par_scan_state->update_rs(_from, p, _par_scan_state->queue_num());
+    _par_scan_state->update_rs(_from, p, _worker_id);
   }
 
   if (do_gen_barrier && obj != NULL) {
@@ -5704,16 +5707,6 @@ void G1CollectedHeap::free_collection_set(HeapRegion* cs_head) {
 
       // And the region is empty.
       assert(!used_mr.is_empty(), "Should not have empty regions in a CS.");
-
-      // If marking is in progress then clear any objects marked in
-      // the current region. Note mark_in_progress() returns false,
-      // even during an initial mark pause, until the set_marking_started()
-      // call which takes place later in the pause.
-      if (mark_in_progress()) {
-        assert(!g1_policy()->during_initial_mark_pause(), "sanity");
-        _cm->nextMarkBitMap()->clearRange(used_mr);
-      }
-
       free_region(cur, &pre_used, &local_free_list, false /* par */);
     } else {
       cur->uninstall_surv_rate_group();

hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp

@@ -1909,7 +1909,7 @@ protected:
   G1ParScanPartialArrayClosure* _partial_scan_cl;
 
   int _hash_seed;
-  int _queue_num;
+  uint _queue_num;
 
   size_t _term_attempts;
 
@@ -1953,7 +1953,7 @@ protected:
   }
 
 public:
-  G1ParScanThreadState(G1CollectedHeap* g1h, int queue_num);
+  G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num);
 
   ~G1ParScanThreadState() {
     FREE_C_HEAP_ARRAY(size_t, _surviving_young_words_base);
@@ -2045,7 +2045,7 @@ public:
   }
 
   int* hash_seed() { return &_hash_seed; }
-  int  queue_num() { return _queue_num; }
+  uint queue_num() { return _queue_num; }
 
   size_t term_attempts() const  { return _term_attempts; }
   void note_term_attempt() { _term_attempts++; }

hotspot/src/share/vm/gc_implementation/g1/g1EvacFailure.hpp

@@ -70,16 +70,20 @@ private:
   OopsInHeapRegionClosure *_update_rset_cl;
   bool _during_initial_mark;
   bool _during_conc_mark;
+  uint _worker_id;
+
 public:
   RemoveSelfForwardPtrObjClosure(G1CollectedHeap* g1, ConcurrentMark* cm,
                                  HeapRegion* hr,
                                  OopsInHeapRegionClosure* update_rset_cl,
                                  bool during_initial_mark,
-                                 bool during_conc_mark) :
+                                 bool during_conc_mark,
+                                 uint worker_id) :
     _g1(g1), _cm(cm), _hr(hr), _marked_bytes(0),
     _update_rset_cl(update_rset_cl),
     _during_initial_mark(during_initial_mark),
-    _during_conc_mark(during_conc_mark) { }
+    _during_conc_mark(during_conc_mark),
+    _worker_id(worker_id) { }
 
   size_t marked_bytes() { return _marked_bytes; }
 
@@ -123,7 +127,7 @@ public:
         // explicitly and all objects in the CSet are considered
         // (implicitly) live. So, we won't mark them explicitly and
         // we'll leave them over NTAMS.
-        _cm->markNext(obj);
+        _cm->grayRoot(obj, obj_size, _worker_id);
       }
       _marked_bytes += (obj_size * HeapWordSize);
       obj->set_mark(markOopDesc::prototype());
@@ -155,12 +159,14 @@ class RemoveSelfForwardPtrHRClosure: public HeapRegionClosure {
   G1CollectedHeap* _g1h;
   ConcurrentMark* _cm;
   OopsInHeapRegionClosure *_update_rset_cl;
+  uint _worker_id;
 
 public:
   RemoveSelfForwardPtrHRClosure(G1CollectedHeap* g1h,
-                                OopsInHeapRegionClosure* update_rset_cl) :
+                                OopsInHeapRegionClosure* update_rset_cl,
+                                uint worker_id) :
     _g1h(g1h), _update_rset_cl(update_rset_cl),
-    _cm(_g1h->concurrent_mark()) { }
+    _worker_id(worker_id), _cm(_g1h->concurrent_mark()) { }
 
   bool doHeapRegion(HeapRegion *hr) {
     bool during_initial_mark = _g1h->g1_policy()->during_initial_mark_pause();
@@ -173,7 +179,8 @@ public:
       if (hr->evacuation_failed()) {
         RemoveSelfForwardPtrObjClosure rspc(_g1h, _cm, hr, _update_rset_cl,
                                             during_initial_mark,
-                                            during_conc_mark);
+                                            during_conc_mark,
+                                            _worker_id);
 
         MemRegion mr(hr->bottom(), hr->end());
         // We'll recreate the prev marking info so we'll first clear
@@ -226,7 +233,7 @@ public:
       update_rset_cl = &immediate_update;
     }
 
-    RemoveSelfForwardPtrHRClosure rsfp_cl(_g1h, update_rset_cl);
+    RemoveSelfForwardPtrHRClosure rsfp_cl(_g1h, update_rset_cl, worker_id);
 
     HeapRegion* hr = _g1h->start_cset_region_for_worker(worker_id);
     _g1h->collection_set_iterate_from(hr, &rsfp_cl);

hotspot/src/share/vm/gc_implementation/g1/g1OopClosures.hpp

@@ -51,6 +51,7 @@ protected:
   G1RemSet* _g1_rem;
   ConcurrentMark* _cm;
   G1ParScanThreadState* _par_scan_state;
+  uint _worker_id;
   bool _during_initial_mark;
   bool _mark_in_progress;
 public:

hotspot/src/share/vm/gc_implementation/g1/heapRegion.hpp

@@ -374,7 +374,9 @@ class HeapRegion: public G1OffsetTableContigSpace {
     ParVerifyClaimValue        = 4,
     RebuildRSClaimValue        = 5,
     CompleteMarkCSetClaimValue = 6,
-    ParEvacFailureClaimValue   = 7
+    ParEvacFailureClaimValue   = 7,
+    AggregateCountClaimValue   = 8,
+    VerifyCountClaimValue      = 9
   };
 
   inline HeapWord* par_allocate_no_bot_updates(size_t word_size) {