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https://issues.apache.org/jira/browse/MAPREDUCE-1225?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12858757#action_12858757
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Amareshwari Sriramadasu commented on MAPREDUCE-1225:
----------------------------------------------------

Comments on the patch :
* Calling the method checkCacheStatusValidity even for the cache that has not 
inited does not solve the problem. checkCacheStatusValidity does the check by 
calling isExistsAndFresh(). isExistsAndFresh does two checks :
 ## dfsFileStamp != confFileStamp
 ## dfsFileStamp != lcacheStatus.mtime
Here, the second check is not valid for the file that is not localized. So, 
isExistsAndFresh() always returns false after the patch. We should refactor the 
first check into a different method and call only that for cache that is not 
yet inited. Does that make sense?
* Can you add a unit test in TestTrackerDistributedCacheManager which fails 
without the patch and passes after the patch ?

> TT successfully localizes a task even though the corresponding cache-file has 
> already changed on DFS.
> -----------------------------------------------------------------------------------------------------
>
>                 Key: MAPREDUCE-1225
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1225
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: tasktracker
>    Affects Versions: 0.21.0, 0.22.0
>            Reporter: Vinod K V
>             Fix For: 0.21.0
>
>         Attachments: MAPREDUCE-1225.patch, MAPREDUCE-1225.patch
>
>
> This happens with the first task of a job being localized on this TT. TT 
> doesn't check if the file on DFS is fresh according to the timestamps set in 
> job-conf during submission. After the first task incorrectly gets localized, 
> all further tasks fail on this TT as expected.
> Found this issue while trying to improve test-case for MAPREUCE-913.

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