code: @Override
    public void doAsActiveServer() {
      try {
        LOG.info("As active master, init timestamp from ZooKeeper");
        chronosImplement.initTimestamp();
      } catch (Exception e) {
        LOG.fatal("Exception to init timestamp from ZooKeeper, exit immediately");
        System.exit(0);
      }
      
      chronosServerWatcher.setBeenActiveMaster(true);
  
      LOG.info("Start to accept thrift request");
      startThriftServer();
    }
docs: Initialize persistent timestamp and start to serve as active master.