boolean close() throws Exception {
    try {
      if (handleGroupKey && groupKey != null) {
        // If a operator wants to do some work at the end of a group
        reducer.endGroup();
      }
    } catch (Exception e) {
      if (!abort) {
        // signal new failure to map-reduce
        throw new RuntimeException("Hive Runtime Error while closing operators: "
            + e.getMessage(), e);
      }
    }
    return abort;
  }
@param keyWritable
@param values
@param tag
@throws HiveException
@throws IOException
ql/src/java/org/apache/hadoop/hive/ql/exec/tez/ReduceRecordSource.java