@Override
    public boolean next(List<? super ExtendedCell> result, ScannerContext context)
      throws IOException {
      if (HeartbeatHRegion.sleepBeforeColumnFamily) HeartbeatHRegion.columnFamilySleep();
      boolean moreRows = super.next(result, context);
      if (!HeartbeatHRegion.sleepBeforeColumnFamily) HeartbeatHRegion.columnFamilySleep();
      return moreRows;
    }
Custom reversed KV Heap that can be configured to sleep in between retrievals of column family
cells.
hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestScannerHeartbeatMessages.java