public void close(Reporter reporter) throws IOException {
      try {
        if (this.m_mutator != null) {
          this.m_mutator.close();
        }
      } finally {
        if (conn != null) {
          this.conn.close();
        }
      }
    }
Instantiate a TableRecordWriter with a BufferedMutator for batch writing.
hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/mapred/TableOutputFormat.java