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https://issues.apache.org/jira/browse/MAPREDUCE-1305?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12791654#action_12791654
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Peter Romianowski commented on MAPREDUCE-1305:
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Yes I am using distcp against file:/// to make a backup of some crucial files
to a NAS.
The better question would be: Why serializing FileStatus if Path is all we need?
> Massive performance problem with DistCp and -delete
> ---------------------------------------------------
>
> Key: MAPREDUCE-1305
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-1305
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: distcp
> Affects Versions: 0.20.1
> Reporter: Peter Romianowski
> Assignee: Peter Romianowski
> Attachments: MAPRED-1305.patch
>
>
> *First problem*
> In org.apache.hadoop.tools.DistCp#deleteNonexisting we serialize FileStatus
> objects when the path is all we need.
> The performance problem comes from
> org.apache.hadoop.fs.RawLocalFileSystem.RawLocalFileStatus#write which tries
> to retrieve file permissions by issuing a "ls -ld <path>" which is painfully
> slow.
> Changed that to just serialize Path and not FileStatus.
> *Second problem*
> To delete the files we invoke the "hadoop" command line tool with option
> "-rmr <path>". Again, for each file.
> Changed that to dstfs.delete(path, true)
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