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https://issues.apache.org/jira/browse/MAPREDUCE-2167?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13016948#comment-13016948
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Hudson commented on MAPREDUCE-2167:
-----------------------------------
Integrated in Hadoop-Mapreduce-trunk #643 (See
[https://hudson.apache.org/hudson/job/Hadoop-Mapreduce-trunk/643/])
> Faster directory traversal for raid node
> ----------------------------------------
>
> Key: MAPREDUCE-2167
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-2167
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: contrib/raid
> Reporter: Ramkumar Vadali
> Assignee: Ramkumar Vadali
> Fix For: 0.22.0
>
> Attachments: MAPREDUCE-2167.2.patch, MAPREDUCE-2167.3.patch,
> MAPREDUCE-2167.4.patch, MAPREDUCE-2167.patch
>
>
> The RaidNode currently iterates over the directory structure to figure out
> which files to RAID. With millions of files, this can take a long time -
> especially if some files are already RAIDed and the RaidNode needs to look at
> parity files / parity file HARs to determine if the file needs to be RAIDed.
> The directory traversal is encapsulated inside the class DirectoryTraversal,
> which examines one file at a time, using the caller's thread.
> My proposal is to make this multi-threaded as follows:
> * use a pool of threads inside DirectoryTraversal
> * The caller's thread is used to retrieve directories, and each new
> directory is assigned to a thread in the pool. The worker thread examines all
> the files the directory.
> * If there sub-directories, those are added back as workitems to the pool.
> Comments?
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