public void set(Boolean b) {
        this.b = b;
      }
Test the non-null value of the Yarn ATS GUID.
We spawn 2 threads - one running the query and
the other attempting to read the ATS GUID.
We're using a dummy udf to simulate a query,
that runs for a sufficiently long time.
@throws Exception
itests/hive-unit/src/test/java/org/apache/hive/jdbc/TestJdbcDriver2.java