[jira] [Commented] (KAFKA-8204) Streams may flush state stores in the incorrect order

["John Roesler (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-8204?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16832592#comment-16832592 ] 

John Roesler commented on KAFKA-8204:
-------------------------------------

2.2.1 has been proposed: https://cwiki.apache.org/confluence/display/KAFKA/Release+Plan+2.2.1

> Streams may flush state stores in the incorrect order
> -----------------------------------------------------
>
>                 Key: KAFKA-8204
>                 URL: https://issues.apache.org/jira/browse/KAFKA-8204
>             Project: Kafka
>          Issue Type: Improvement
>          Components: streams
>    Affects Versions: 1.1.0, 1.1.1, 2.0.0, 2.0.1, 2.1.0, 2.2.0, 2.1.1
>            Reporter: John Roesler
>            Assignee: John Roesler
>            Priority: Blocker
>             Fix For: 2.3.0, 2.2.1
>
>
> Cached state stores may forward records during a flush call, so Streams should flush the stores in topological order. Otherwise, Streams may flush a downstream store before an upstream one, resulting in sink results being committed without the corresponding state changelog updates being committed.
> This behavior is partly responsible for the bug reported in KAFKA-7895 .
> The fix is simply to flush the stores in topological order, then when the upstream store forwards records to a downstream stateful processor, the corresponding state changes will be correctly flushed as well.
> An alternative would be to repeatedly call flush on all state stores until they report there is nothing left to flush, but this requires a public API change to enable state stores to report whether they need a flush or not.



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