[jira] [Updated] (CURATOR-15) LeaderSelector may (undetectably) fail to elect

["Jordan Zimmerman (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/CURATOR-15?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jordan Zimmerman updated CURATOR-15:
------------------------------------

    Fix Version/s:     (was: next-release)
                   TBD
    
> LeaderSelector may (undetectably) fail to elect
> -----------------------------------------------
>
>                 Key: CURATOR-15
>                 URL: https://issues.apache.org/jira/browse/CURATOR-15
>             Project: Apache Curator
>          Issue Type: Bug
>          Components: Recipes
>    Affects Versions: 2.0.0-incubating
>            Reporter: Shevek
>             Fix For: TBD
>
>
> In LeaderSelector, if mutex.acquire() throws an Exception, for example because CuratorFramework.getZooKeeper() threw a previously-enqueued background exception, then that failure will propagate out of doWork and doWorkLoop, and kill the background submission onto the executor service.
> This means that a leaderselector which was start()ed will NEVER elect, and this situation is NOT DETECTABLE externally, since that exception happens on a private executorservice thread and is not client visible. It's impossible to look at a LeaderSelector and decide whether it is still "viable".
> This can leave a machine/process "hung" and not automatically recoverable within curator.
> Either isQueued() needs to be exposed, which means that a leader is either elected or queued; or the finally{} block which calls clearIsQueued() needs also to set state to CLOSED or FAILED, so that we can query this failure externally.

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