@Override
    public DAGStatus getDAGStatus(@Nullable Set<StatusGetOpts> statusOptions)
        throws IOException, TezException {
      synchronized (dagClient) {
        return dagClient.getDAGStatus(statusOptions);
      }
    }
DAG client that does dumb global sync on all the method calls;
Tez DAG client is not thread safe and getting the 2nd one is not recommended.
ql/src/java/org/apache/hadoop/hive/ql/exec/tez/TezTask.java