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https://issues.apache.org/jira/browse/KAFKA-4851?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Guozhang Wang resolved KAFKA-4851.
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Resolution: Fixed
Fix Version/s: 0.10.2.1
Issue resolved by pull request 2645
[https://github.com/apache/kafka/pull/2645]
> SessionStore.fetch(key) is a performance bottleneck
> ---------------------------------------------------
>
> Key: KAFKA-4851
> URL: https://issues.apache.org/jira/browse/KAFKA-4851
> Project: Kafka
> Issue Type: Bug
> Components: streams
> Affects Versions: 0.10.2.0
> Reporter: Damian Guy
> Assignee: Damian Guy
> Fix For: 0.11.0.0, 0.10.2.1
>
>
> When flushing the {{CachingSessionStore}} we need to search for the previous
> value for a session. This involves searching each open RocksDB segment. The
> code ends up doing a call {{Segments.segments(0, Long.MAX_VALUE)}} this
> results in approximately 3 million gets on a {{ConcurrentHashMap}} of which
> all but 3 of them will be hits.
> Change this code to restrict the segmentIds to search just to the available
> set.
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