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From "Mike Drob (JIRA)" <>
Subject [jira] [Updated] (CURATOR-7) Session ids not preserved if EnsembleProvider has changed the ensemble
Date Wed, 30 Jul 2014 18:36:41 GMT


Mike Drob updated CURATOR-7:

    Attachment: CURATOR-7.patch.txt

Attaching a version of Shevek's patch against the apache code base. It looks like it depends
on ZK-3.5, based on his original naming, so it does not compile as applied to master. I have
not looked at it in enough detail to figure out if that is something that can be aligned with
ZK-3.4 or not.

> Session ids not preserved if EnsembleProvider has changed the ensemble
> ----------------------------------------------------------------------
>                 Key: CURATOR-7
>                 URL:
>             Project: Apache Curator
>          Issue Type: Improvement
>          Components: Client
>    Affects Versions: 2.0.0-incubating
>            Reporter: Shevek
>             Fix For: awaiting-response
>         Attachments: CURATOR-7.patch.txt, EnsembleProvider-zookeeper-3.5.x.patch
> See
> 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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