title: Keep Solr slaves in sync
body: <p>We have a master-slave setup running Solr 6.5.0. There is a backend process running 24/7 which pushes its data towards the master server. No commit is done on master. The web frontend is accessing the slave. Replication poll interval is 1 hour.</p>
  
  <p>All is fine so far, but now as the traffic grows, the CPU load on slave is really high. I thought the best thing would be to add a second slave to the master and let the web servers connect via existing load balancers to the two Solr slave machines. I think that the two Solr slaves will handle their replication independently and each slave will poll the master at another time. </p>
  
  <p>As the master receives 24/7 new data I'm worried that both machines do not have the same data set/version. Is there a solution with low administration effort to force both slaves polling new data from master at the same time? (I.e. I'm trying to avoid setting up a real Solr cluster as multiple slaves will fit our needs.)</p>