code: protected void reportNextRecordRange(final TaskUmbilicalProtocol umbilical, 
        long nextRecIndex) throws IOException{
      //currentRecStartIndex is the start index which has not yet been finished 
      //and is still in task's stomach.
      long len = nextRecIndex - currentRecStartIndex +1;
      SortedRanges.Range range = 
        new SortedRanges.Range(currentRecStartIndex, len);
      taskStatus.setNextRecordRange(range);
      LOG.debug("sending reportNextRecordRange " + range);
      umbilical.reportNextRecordRange(taskId, range);
    }
docs: Reports the next executing record range to TaskTracker.
  
  @param umbilical
  @param nextRecIndex the record index which would be fed next.
  @throws IOException