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From "Siddharth Seth (Updated) (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (MAPREDUCE-3710) last split generated by FileInputFormat.getSplits may not have the best locality
Date Mon, 23 Jan 2012 19:15:40 GMT

     [ https://issues.apache.org/jira/browse/MAPREDUCE-3710?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Siddharth Seth updated MAPREDUCE-3710:
--------------------------------------

    Attachment: MR-3710_v1.txt

Patch for the last split.
Mapred.FileInputFormat seems to have additional optimizations for rack locality which don't
exist in mapreduce.FileInputFormat. The patch does not include a fix for this.
                
> last split generated by FileInputFormat.getSplits may not have the best locality
> --------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-3710
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-3710
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: mrv1, mrv2
>    Affects Versions: 0.23.0, 1.0.0
>            Reporter: Siddharth Seth
>            Assignee: Siddharth Seth
>         Attachments: MR-3710_v1.txt
>
>
> The last split generated by FileInputFormat.getSplits considers {{blkLocations.length-1}}
to be the hosts for the split.
> The last split may be larger than the rest (SPLIT_SLOP=1.1 by default) - in which case
locality is picked up from a smaller block.
> e.g. 1027MB file with a 128MB split size. The last split ends up being 131MB. The hosts
for locality end up being the nodes containing the 3MB block instead of the 128MB block.

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