fix:Memory leak exists in the function runCmd() in the class QueryRunner.

Hive Relevant code:

static Map<HiveConf, Driver> mapDrivers = new HashMap<HiveConf, Driver>();


public static CommandProcessor get(String cmd, HiveConf conf) {
    String cmdl = cmd.toLowerCase();

    if ("set".equals(cmdl)) {
      return new SetProcessor();
    } else if ("dfs".equals(cmdl)) {
      SessionState ss = SessionState.get();
      return new DfsProcessor(ss.getConf());
    } else if ("add".equals(cmdl)) {
      return new AddResourceProcessor();
    } else if ("delete".equals(cmdl)) {
      return new DeleteResourceProcessor();
    } else if (!isBlank(cmd)) {
      if (conf == null) {
        return new Driver();
      }

      Driver drv = mapDrivers.get(conf);
      if (drv == null) {
        drv = new Driver();
        mapDrivers.put(conf, drv);
      }
      drv.init();
      return drv;
    }