[jira] [Commented] (KAFKA-5793) Tighten up situations where OutOfOrderSequence may be returned

["ASF GitHub Bot (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KAFKA-5793?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16167186#comment-16167186 ] 

ASF GitHub Bot commented on KAFKA-5793:
---------------------------------------

GitHub user apurvam opened a pull request:

    https://github.com/apache/kafka/pull/3865

    KAFKA-5793: Tighten up the semantics of the OutOfOrderSequenceException

    *WIP : Don't review yet, still to add tests*
    
    Description of the solution can be found here: https://cwiki.apache.org/confluence/display/KAFKA/Kafka+Exactly+Once+-+Solving+the+problem+of+spurious+OutOfOrderSequence+errors
    


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

    $ git pull https://github.com/apurvam/kafka KAFKA-5793-tighten-up-out-of-order-sequence-v2

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

    https://github.com/apache/kafka/pull/3865.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 #3865
    
----
commit fb44876987bd2f75c900b187fdc755da3f85114f
Author: Apurva Mehta <ap...@confluent.io>
Date:   2017-09-15T01:01:58Z

    Initial commit of the client and server code, with minimal tests

----


> Tighten up situations where OutOfOrderSequence may be returned
> --------------------------------------------------------------
>
>                 Key: KAFKA-5793
>                 URL: https://issues.apache.org/jira/browse/KAFKA-5793
>             Project: Kafka
>          Issue Type: Sub-task
>    Affects Versions: 0.11.0.0
>            Reporter: Apurva Mehta
>            Assignee: Apurva Mehta
>             Fix For: 1.0.0
>
>
> Details of the problem are provided here: https://cwiki.apache.org/confluence/display/KAFKA/Kafka+Exactly+Once+-+Solving+the+problem+of+spurious+OutOfOrderSequence+errors
> A quick summary follows:
> In the discussion of KIP-185: Make exactly once in order delivery per partition the default producer setting, the following point regarding the OutOfOrderSequenceException was raised:
> 1. The OutOfOrderSequenceException indicates that there has been data loss on the broker.. ie. a previously acknowledged message no longer exists. For most part, this should only occur in rare situations (simultaneous power outages, multiple disk losses, software bugs resulting in data corruption, etc.).
> 2. However, there is another perfectly normal scenario where data is removed: in particular, data could be deleted because it is old and crosses the retention threshold.
> Hence, if a producer remains inactive for longer than a topic's retention period, we could get an OutOfOrderSequence which is a false positive: the data is removed through valid processes, and this isn't an error.
> 3. We would like to eliminate the possibility of getting spurious OutOfOrderSequenceExceptions – when you get it, it should always mean data loss and should be taken very seriously. 



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