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https://issues.apache.org/jira/browse/ZOOKEEPER-571?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15963101#comment-15963101
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Marco P. commented on ZOOKEEPER-571:
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Related: https://issues.apache.org/jira/browse/ZOOKEEPER-2748
> support balancing of client load across servers in an ensemble
> --------------------------------------------------------------
>
> Key: ZOOKEEPER-571
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-571
> Project: ZooKeeper
> Issue Type: Improvement
> Components: quorum, server
> Reporter: Patrick Hunt
>
> Currently the ensemble does not ensure a balanced load across servers in an
> ensemble. Clients randomly connect to
> a server, which typically balances the number of sessions. However there are
> problems with this:
> 1) session count is balanced, but not session load
> 2) if server A goes down all of the sessions on that server migrate to other
> servers in the cluster randomly, this is fine, however
> when server A comes back into service it will have no sessions, and migration
> of sessions from other servers may take time
> The quorum should probably have some way of broadcasting load, and
> occasionally re-balance the sessions based on
> this information. Might be tricky though, want to ensure that we aren't
> constantly ping-ponging sessions to servers.
> Probably need some hysteresis as well as limit the frequency. Real time
> tuning would need to be supported.
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