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https://issues.apache.org/jira/browse/KAFKA-4851?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15900385#comment-15900385
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ASF GitHub Bot commented on KAFKA-4851:
---------------------------------------

Github user asfgit closed the pull request at:

    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
>
>
> 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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