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https://issues.apache.org/jira/browse/MAPREDUCE-1288?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12892948#action_12892948
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Devaraj Das commented on MAPREDUCE-1288:
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bq. Devaraj, this corner case is exactly what Hemanth was trying to explain
earlier on this ticket, starting with comment #4 above
Yeah.. i realized that.. That's the reason i stuck to this jira rather than
opening a new one :-)
bq. As for the approach, we have two options: (1) (this seems to be what the
patch is doing) for group shared files, localize them separately for each user.
This is a simple solution, but sacrifices the optimization ( may not be too
bad?)
Yes, I am going with this for now. If needed (after we deploy this patch on our
clusters and observe), we can look at proposal (2) in your comment..
> DistributedCache localizes only once per cache URI
> --------------------------------------------------
>
> Key: MAPREDUCE-1288
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-1288
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: distributed-cache, security, tasktracker
> Affects Versions: 0.21.0
> Reporter: Devaraj Das
> Priority: Critical
> Attachments: MR-1288-bp20-1.patch, MR-1288-bp20-2.patch,
> MR-1288-bp20-3.patch
>
>
> As part of the file localization the distributed cache localizer creates a
> copy of the file in the corresponding user's private directory. The
> localization in DistributedCache assumes the key as the URI of the cachefile
> and if it already exists in the map, the localization is not done again. This
> means that another user cannot access the same distributed cache file. We
> should change the key to include the username so that localization is done
> for every user.
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