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From "Shevek (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CURATOR-7) Session ids not preserved if EnsembleProvider has changed the ensemble
Date Tue, 26 Mar 2013 23:51:17 GMT

    [ https://issues.apache.org/jira/browse/CURATOR-7?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13614698#comment-13614698
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Shevek commented on CURATOR-7:
------------------------------

The ZooKeeper documentation suggests that sessionId may change after a reconnect (within the
native ZK handle) so I suspect we can safely pass a duff sessionId through ZookeeperFactory.
                
> Session ids not preserved if EnsembleProvider has changed the ensemble
> ----------------------------------------------------------------------
>
>                 Key: CURATOR-7
>                 URL: https://issues.apache.org/jira/browse/CURATOR-7
>             Project: Apache Curator
>          Issue Type: Improvement
>          Components: Client
>    Affects Versions: 2.0.0
>            Reporter: Shevek
>            Assignee: Jordan Zimmerman
>
> See https://github.com/Netflix/curator/issues/266
> InterProcessMutex, LeaderLatch, etc use an ephemeral node. If ZooKeeper gives a Disconnected
event, the native client reconnects with the same session id, and the ephemeral node is preserved.
If the ensemble changes at any point before a Disconnect, Curator's ConnectionState#checkState()
calls handleNewConnectionString(), which constructs a new native ZK client, discarding the
previous session id, and losing all locks.
> This can be expensive.
> Can ConnectionState be made to preserve the session id, or be more conservative about
discarding the entire native client on a Disconnected event?
> Clarifications:
> An ensemble change (e.g. adding a new node to a cluster) does not mean that all session
ids are now invalid. The next network glitch should not break locks.
> There is no assumption in this description that the reconfiguration and the glitch/disconnection
were related - they need not be.

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