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https://issues.apache.org/jira/browse/KAFKA-2799?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14999374#comment-14999374
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ASF GitHub Bot commented on KAFKA-2799:
---------------------------------------

GitHub user guozhangwang opened a pull request:

    https://github.com/apache/kafka/pull/490

    KAFKA-2799: skip wakeup in the follow-up poll() call.

    

You can merge this pull request into a Git repository by running:

    $ git pull https://github.com/guozhangwang/kafka K2799

Alternatively you can review and apply these changes as the patch at:

    https://github.com/apache/kafka/pull/490.patch

To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:

    This closes #490
    
----
commit f9dd6ffbfa975ab454b84c43c722767d74d572ed
Author: Guozhang Wang <wangg...@gmail.com>
Date:   2015-11-10T21:32:07Z

    v1

----


> WakupException thrown in the followup poll() could lead to data loss
> --------------------------------------------------------------------
>
>                 Key: KAFKA-2799
>                 URL: https://issues.apache.org/jira/browse/KAFKA-2799
>             Project: Kafka
>          Issue Type: Bug
>            Reporter: Guozhang Wang
>            Assignee: Guozhang Wang
>            Priority: Blocker
>             Fix For: 0.9.0.0
>
>
> The common pattern of the new consumer:
> {code}
> try {
>    records = consumer.poll();
>    // process records
> } catch (WakeupException) {
>    consumer.close()
> }
> {code}
> in which the close() can commit offsets. But since in the poll() call, we do 
> the following order:
> 1) trigger client.poll().
> 2) possibly update consumed position if there are some data from fetch 
> response.
> 3) before return the records, possibly trigger another client.poll()
> And if wakeup exception is thrown in 3) it will lead to not-returned messages 
> to be committed hence data loss.



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