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https://issues.apache.org/jira/browse/SAMZA-1621?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Shanthoosh Venkataraman closed SAMZA-1621.
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> Delete the ephemeral processor node in StreamProcessor shutdown phase.
> ----------------------------------------------------------------------
>
> Key: SAMZA-1621
> URL: https://issues.apache.org/jira/browse/SAMZA-1621
> Project: Samza
> Issue Type: Bug
> Reporter: Shanthoosh Venkataraman
> Assignee: Shanthoosh Venkataraman
> Priority: Major
>
> Currently when a StreamProcessor dies, we rely upon the session expiration
> phase in zookeeper to delete the ephemeral processor node in zookeeper. This
> behavior might not be acceptable in the following scenarios.
> A. In standalone, we disallow multiple processors in a group to have the same
> processorId. If the zookeeper session timeout is greater than the processor
> restart time, then upon restart, the processor will be unable to join the
> group with the same processorId(since there will be a ephemeral node in
> zookeeper with processorId corresponding to the restarted processor).
> B. In zookeeper the writes are serialized by a single writer thread
> performing actions out of a request queue. In cases, where the request queue
> is flooded by zookeeper write/delete requests from other processes, action
> for session expiration will be delayed more than the configured zookeeper
> session timeout.
> Moreover, the general notion behind the zookeeper session timeout is to
> safeguard the StreamProcessors from network partitioning(as well as transient
> failures in the zookeeper server ensemble). Leaving the zookeeper ephemeral
> processor nodes to remain after the StreamProcessor shutdown doesn't add much
> value.
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