Mailing-List: contact mapreduce-issues-help@hadoop.apache.org; run by ezmlm
Precedence: bulk
Reply-To: mapreduce-issues@hadoop.apache.org
Date: Wed, 28 Nov 2012 16:49:00 +0000 (UTC)
From: "Jason Lowe (JIRA)" <jira@apache.org>
To: mapreduce-issues@hadoop.apache.org
Message-ID: <1370003815.33463.1354121340501.JavaMail.jiratomcat@arcas>
In-Reply-To: <1309689274.24015.1353956698669.JavaMail.jiratomcat@arcas>
Subject: [jira] [Commented] (MAPREDUCE-4819) AM can rerun job after
 reporting final job status to the client
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit


    [ https://issues.apache.org/jira/browse/MAPREDUCE-4819?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13505644#comment-13505644 ] 

Jason Lowe commented on MAPREDUCE-4819:
---------------------------------------

bq. My vote would be to leave it around until we are done done and staging is removed. It seems simpler.

Agreed, although we would also need to make sure we only delete the staging directory after unregistering from the RM.  Something we need to do anyway, see YARN-244.
                
> AM can rerun job after reporting final job status to the client
> ---------------------------------------------------------------
>
>                 Key: MAPREDUCE-4819
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-4819
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: mr-am
>    Affects Versions: 0.23.3, 2.0.1-alpha
>            Reporter: Jason Lowe
>            Assignee: Bikas Saha
>            Priority: Critical
>
> If the AM reports final job status to the client but then crashes before unregistering with the RM then the RM can run another AM attempt.  Currently AM re-attempts assume that the previous attempts did not reach a final job state, and that causes the job to rerun (from scratch, if the output format doesn't support recovery).
> Re-running the job when we've already told the client the final status of the job is bad for a number of reasons.  If the job failed, it's confusing at best since the client was already told the job failed but the subsequent attempt could succeed.  If the job succeeded there could be data loss, as a subsequent job launched by the client tries to consume the job's output as input just as the re-attempt starts removing output files in preparation for the output commit.

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira