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https://issues.apache.org/jira/browse/SAMZA-1689?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Xinyu Liu resolved SAMZA-1689.
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Resolution: Fixed
> Add validations before state transitions in ZkBarrierForVersionUpgrade.
> ------------------------------------------------------------------------
>
> Key: SAMZA-1689
> URL: https://issues.apache.org/jira/browse/SAMZA-1689
> Project: Samza
> Issue Type: Bug
> Reporter: Shanthoosh Venkataraman
> Assignee: Shanthoosh Venkataraman
> Priority: Major
> Fix For: 0.14.1
>
>
> *Problem:*
> A barrier in zookeeper can be in either DONE or TimedOut state. Existing
> ZkBarrier implementation doesn't have any state validations before acting
> upon the barrier events received from zookeeper. This can corrupt barrier
> states when any of the following occur:
> - When a stream processor joins a barrier marked as timed out by the leader
> of the group.
> - When the leader of a group expires a barrier marked as Done. This can
> happen when a leader plays out a stale events from its in-memory buffer.
> This will cause the processors group to go through unnecessary rebalancing
> phase(worse, corrupt the barrier state).
> *Changes:*
> - Introduce a barrier state: NEW which will be the beginning state of a
> barrier(In existing implementation, barrier is created with empty/null
> value). Barrier will be marked as Done or TimedOut only if the current
> barrier state is NEW.
> - Fix the disabled barrier test cases. Add new test cases to validate the
> changed functionality.
> - Improve logging to aid debugging.
>
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