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https://issues.apache.org/jira/browse/S4-3?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Matthieu Morel updated S4-3:
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Affects Version/s: 0.3
> Sometimes one process node owns 2 tasks
> ---------------------------------------
>
> Key: S4-3
> URL: https://issues.apache.org/jira/browse/S4-3
> Project: Apache S4
> Issue Type: Bug
> Affects Versions: 0.3
> Reporter: Gavin Li
> Assignee: Gavin Li
> Attachments: losconnfix2, s4_loscon_fix
>
>
> When using S4, we found sometimes it ends up with one process node owns 2
> tasks. I did some investigation, it seems that the handling of
> ConnectionLossException when creating the ephemeral node is problematic.
> Sometimes when the response from zookeeper server times out,
> zookeeper.create() will fail with ConnectionLossException while the creation
> request might already be sent to server(see
> http://svn.apache.org/viewvc/hadoop/zookeeper/trunk/src/java/main/org/apache/zookeeper/ClientCnxn.java
> line 830). From our logs this is the case we ran into.
> Maybe we should handle it in the way that HBase is handling it
> (http://svn.apache.org/viewvc/hbase/trunk/src/main/java/org/apache/hadoop/hbase/zookeeper/ZKUtil.java?view=markup),
> just simply exit the process when got that exception to let the whole
> process restart.
> To be more clear, what happened was: a process node called zookeeper.create()
> to acquire a task, the request was successfully sent to zookeeper server, but
> the zookeeper IO loop timed out before the response came. So the
> zookeeper.create() failed with ConnectionLossException. Then the process node
> ignored this exception and tried to acquire another task. Then it got 2 tasks.
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