@Override
  public long runFrequency(TimeUnit unit) {
    return MetastoreConf.getTimeVar(conf, MetastoreConf.ConfVars.TXN_TIMEOUT, unit) / 2;
  }
Cleaner for the {@link MaterializationsRebuildLockHandler}. It removes outdated locks
in the intervals specified by the input property.
standalone-metastore/metastore-server/src/main/java/org/apache/hadoop/hive/metastore/MaterializationsRebuildLockCleanerTask.java