[jira] [Commented] (KAFKA-7703) KafkaConsumer.position may return a wrong offset after "seekToEnd" is called

["Shixiong Zhu (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-7703?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16708272#comment-16708272 ] 

Shixiong Zhu commented on KAFKA-7703:
-------------------------------------

This seems introduced by KAFKA-6397 which moved the offset updating codes into a different thread.

> KafkaConsumer.position may return a wrong offset after "seekToEnd" is called
> ----------------------------------------------------------------------------
>
>                 Key: KAFKA-7703
>                 URL: https://issues.apache.org/jira/browse/KAFKA-7703
>             Project: Kafka
>          Issue Type: Bug
>          Components: clients
>    Affects Versions: 2.1.0
>            Reporter: Shixiong Zhu
>            Priority: Major
>
> After "seekToEnd" is called, "KafkaConsumer.position" may return a wrong offset set by another reset request.
> Here is a reproducer: https://github.com/zsxwing/kafka/commit/4e1aa11bfa99a38ac1e2cb0872c055db56b33246
> In this reproducer, "poll(0)" will send an "earliest" request in background. However, after "seekToEnd" is called, due to a race condition in "Fetcher.resetOffsetIfNeeded" (It's not atomic, "seekToEnd" could happen between the check https://github.com/zsxwing/kafka/commit/4e1aa11bfa99a38ac1e2cb0872c055db56b33246#diff-b45245913eaae46aa847d2615d62cde0R585 and the seek https://github.com/zsxwing/kafka/commit/4e1aa11bfa99a38ac1e2cb0872c055db56b33246#diff-b45245913eaae46aa847d2615d62cde0R605), "KafkaConsumer.position" may return an "earliest" offset.



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