@After
  public void tearDown() throws Exception {
    if (txnMgr != null) txnMgr.closeTxnManager();
    TestTxnDbUtil.cleanDb(conf);
    ThreadPool.shutdown();
  }
Same as testHeartbeater, but testing cleanup of replication txns (TxnType.REPL_CREATED)
Note: in TestDbTxnManager metastore.repl.txn.timeout is set to 30s for testing purposes.
ql/src/test/org/apache/hadoop/hive/ql/lockmgr/TestDbTxnManager.java