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From "Tsz Wo (Nicholas), SZE (JIRA)" <j...@apache.org>
Subject [jira] Commented: (MAPREDUCE-1752) Implement getFileBlockLocations in HarFilesystem
Date Thu, 27 May 2010 22:35:40 GMT

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Tsz Wo (Nicholas), SZE commented on MAPREDUCE-1752:
---------------------------------------------------

> I guess my approach was making it right and then looking at the ways we can optimize
it rather then trying to hack up a fast solution right from the start.
> Do you have any other ideas that may be worth exploring?

Yes, your approach totally make sense.  A potential improvement would be caching the masterIndex,
archiveIndex and all the file statuses since a client calls getBlockLocation(..) multiple
times for submitting a job.

> Implement getFileBlockLocations in HarFilesystem
> ------------------------------------------------
>
>                 Key: MAPREDUCE-1752
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1752
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: harchive
>            Reporter: Dmytro Molkov
>            Assignee: Dmytro Molkov
>             Fix For: 0.22.0
>
>         Attachments: MR-1752.patch
>
>
> To efficiently run map reduce on the data that has been HAR'ed it will be great to actually
implement getFileBlockLocations for a given filename.
> This way the JobTracker will have information about data locality and will schedule tasks
appropriately.
> I believe the overhead introduced by doing lookups in the index files can be smaller
than that of copying data over the wire.
> Will upload the patch shortly, but would love to get some feedback on this. And any ideas
on how to test it are very welcome.

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