private long elapsedSince(long start) {
    return (System.currentTimeMillis() - start) / 1000;
  }
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