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https://issues.apache.org/jira/browse/KAFKA-1144?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13831608#comment-13831608
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Jun Rao commented on KAFKA-1144:
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Thanks for the patch. A couple of things.
1. We have a jira that tries to move the storage of offsets off ZK
(https://issues.apache.org/jira/browse/KAFKA-1000) since ZK is not really
designed for that. So, we may not be able to do conditional updates for offsets
in the future.
2. We will be rewriting the consumer client
(https://cwiki.apache.org/confluence/display/KAFKA/Client+Rewrite). In the new
api, we will add a callback during consumer rebalances. Do you think that
addresses your issue as well?
> commitOffsets can be passed the offsets to commit
> -------------------------------------------------
>
> Key: KAFKA-1144
> URL: https://issues.apache.org/jira/browse/KAFKA-1144
> Project: Kafka
> Issue Type: Improvement
> Components: consumer
> Affects Versions: 0.8
> Reporter: Imran Rashid
> Assignee: Neha Narkhede
> Attachments:
> 0001-allow-committing-of-arbitrary-offsets-to-facilitate-.patch,
> 0002-add-protection-against-backward-commits.patch
>
>
> This adds another version of commitOffsets that takes the offsets to commit
> as a parameter.
> Without this change, getting correct user code is very hard. Despite kafka's
> at-least-once guarantees, most user code doesn't actually have that
> guarantee, and is almost certainly wrong if doing batch processing. Getting
> it right requires some very careful synchronization between all consumer
> threads, which is both:
> 1) painful to get right
> 2) slow b/c of the need to stop all workers during a commit.
> This small change simplifies a lot of this. This was discussed extensively on
> the user mailing list, on the thread "are kafka consumer apps guaranteed to
> see msgs at least once?"
> You can also see an example implementation of a user api which makes use of
> this, to get proper at-least-once guarantees by user code, even for batches:
> https://github.com/quantifind/kafka-utils/pull/1
> I'm open to any suggestions on how to add unit tests for this.
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