@Override
  public long runFrequency(TimeUnit unit) {
    return MetastoreConf.getTimeVar(conf, MetastoreConf.ConfVars.ACID_HOUSEKEEPER_SERVICE_INTERVAL, unit);
  }
Performs background tasks for Transaction management in Hive.
Runs inside Hive Metastore Service.
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/txn/service/AcidHouseKeeperService.java