src/hotspot/share/gc/g1/g1RemSet.cpp

rev 56956 : 8141637: Parallelize single threaded heap region iteration during Pre Evacuate Collection Set
Reviewed-by:

*** 194,227 ****
          }
        }
      }
    };
  
-   // Creates a snapshot of the current _top values at the start of collection to
-   // filter out card marks that we do not want to scan.
-   class G1ResetScanTopClosure : public HeapRegionClosure {
-     G1RemSetScanState* _scan_state;
- 
-   public:
-     G1ResetScanTopClosure(G1RemSetScanState* scan_state) : _scan_state(scan_state) { }
- 
-     virtual bool do_heap_region(HeapRegion* r) {
-       uint hrm_index = r->hrm_index();
-       if (r->in_collection_set()) {
-         // Young regions had their card table marked as young at their allocation;
-         // we need to make sure that these marks are cleared at the end of GC, *but*
-         // they should not be scanned for cards.
-         // So directly add them to the "all_dirty_regions".
-         // Same for regions in the (initial) collection set: they may contain cards from
-         // the log buffers, make sure they are cleaned.
-         _scan_state->add_all_dirty_region(hrm_index);
-        } else if (r->is_old_or_humongous_or_archive()) {
-         _scan_state->set_scan_top(hrm_index, r->top());
-        }
-        return false;
-      }
-   };
    // For each region, contains the maximum top() value to be used during this garbage
    // collection. Subsumes common checks like filtering out everything but old and
    // humongous regions outside the collection set.
    // This is valid because we are not interested in scanning stray remembered set
    // entries from free or archive regions.
--- 194,203 ----
*** 333,345 ****
        clear_scan_top((uint)i);
      }
  
      _all_dirty_regions = new G1DirtyRegions(_max_regions);
      _next_dirty_regions = new G1DirtyRegions(_max_regions);
- 
-     G1ResetScanTopClosure cl(this);
-     G1CollectedHeap::heap()->heap_region_iterate(&cl);
    }
  
    void prepare_for_merge_heap_roots() {
      _all_dirty_regions->merge(_next_dirty_regions);
  
--- 309,318 ----
*** 907,916 ****
--- 880,906 ----
      p->record_or_add_thread_work_item(scan_phase, worker_id, cl.opt_refs_scanned(), G1GCPhaseTimes::ScanHRScannedOptRefs);
      p->record_or_add_thread_work_item(scan_phase, worker_id, cl.opt_refs_memory_used(), G1GCPhaseTimes::ScanHRUsedMemory);
    }
  }
  
+ // Creates a snapshot of the current _top values at the start of collection to
+ // filter out card marks that we do not want to scan.
+ void G1RemSet::prepare_region_for_scanning(HeapRegion* region) {
+   uint hrm_index = region->hrm_index();
+   if (region->in_collection_set()) {
+     // Young regions had their card table marked as young at their allocation;
+     // we need to make sure that these marks are cleared at the end of GC, *but*
+     // they should not be scanned for cards.
+     // So directly add them to the "all_dirty_regions".
+     // Same for regions in the (initial) collection set: they may contain cards from
+     // the log buffers, make sure they are cleaned.
+     _scan_state->add_all_dirty_region(hrm_index);
+   } else if (region->is_old_or_humongous_or_archive()) {
+     _scan_state->set_scan_top(hrm_index, region->top());
+   }
+ }
+ 
  void G1RemSet::prepare_for_scan_heap_roots() {
    G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
    dcqs.concatenate_logs();
  
    _scan_state->prepare();