@After
  public void tearDown() throws Exception {
    driver.close();
    conf.unset(ValidTxnList.VALID_TXNS_KEY);
    
    driver2.close();
    if (txnMgr != null) {
      txnMgr.closeTxnManager();
    }
    FileUtils.deleteDirectory(new File(conf.getTestDataDir()));
  }
Base class for "end-to-end" tests for DbTxnManager and simulate concurrent queries.
ql/src/test/org/apache/hadoop/hive/ql/lockmgr/DbTxnManagerEndToEndTestBase.java