[jira] [Commented] (MAPREDUCE-2384) Can MR make error response Immediately?

["Harsh J Chouraria (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/MAPREDUCE-2384?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13030471#comment-13030471 ] 

Harsh J Chouraria commented on MAPREDUCE-2384:
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1. is an easy one to fix (basically to move job spec check a step up). I have a patch for this in pipeline.

2. as per OP, is to not build JIP until after the config checks. I think it is alright to have it the way it is now, since to check pre-JIP construct would still require one extra lookup to occur (the config props that are to be checked, are also used elsewhere later). Besides, its easier to read/maintain with the JIP methods and I don't think the construction time (a few property loads, some array decls) would take much time.

What are your thoughts on 2.; would we benefit enough to refactor the parts to not use JIP (and construct it only after validity is verified)?

> 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 Chouraria
>
> 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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