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https://issues.apache.org/jira/browse/MAPREDUCE-2384?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13073358#comment-13073358
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Harsh J commented on MAPREDUCE-2384:
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FWIW, the only place this change could interfere with is that
OutputFormat#checkOutputSpecs() can't no longer find distributed cache files on
the JT FS. Don't think that really matters since you can directly access stuff
on the HDFS/LocalFS to workaround (as is the case with how the DC is loaded).
> Can MR make error response Immediately?
> ---------------------------------------
>
> Key: MAPREDUCE-2384
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-2384
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: job submission
> Affects Versions: 0.21.0
> Reporter: Denny Ye
> Assignee: Harsh J
> Fix For: 0.23.0
>
> Attachments: MAPREDUCE-2384.r1.diff, MAPREDUCE-2384.r2.diff
>
>
> When I read the source code of MapReduce in Hadoop 0.21.0, sometimes it made
> me confused about error response. For example:
> 1. JobSubmitter checking output for each job. MapReduce makes rule to
> limit that each job output must be not exist to avoid fault overwrite. In my
> opinion, MR should verify output at the point of client submitting. Actually,
> it copies related files to specified target and then, doing the verifying.
> 2. JobTracker. Job has been submitted to JobTracker. In first step,
> JT create JIT object that is very "huge" . Next step, JT start to verify job
> queue authority and memory requirements.
>
> In normal case, verifying client input then response immediately if
> any cases in fault. Regular logic can be performed if all the inputs have
> passed.
> It seems like that those code does not make sense for understanding.
> Is only my personal opinion? Wish someone help me to explain the details.
> Thanks!
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