@Override
  public int lockTable(Hive db, LockTableDesc lockTbl) throws HiveException {
    super.lockTable(db, lockTbl);
    throw new UnsupportedOperationException();
  }
Start the heartbeater threadpool and return the task.
@param initialDelay time to delay before first execution, in milliseconds
@return heartbeater
ql/src/java/org/apache/hadoop/hive/ql/lockmgr/DbTxnManager.java