[
https://issues.apache.org/jira/browse/MAPREDUCE-4815?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14242632#comment-14242632
]
Dave Marion commented on MAPREDUCE-4815:
----------------------------------------
Assuming that the output directory is created in setupJob makes sense, but may
be invalid for any extensions of FileOutputCommitter that don't call
super.setupJob() if they override the method. The fix in mergePaths seems easy
and safe.
> FileOutputCommitter.commitJob can be very slow for jobs with many output files
> ------------------------------------------------------------------------------
>
> Key: MAPREDUCE-4815
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-4815
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: mrv2
> Affects Versions: 0.23.3, 2.0.1-alpha, 2.4.1
> Reporter: Jason Lowe
> Assignee: Siqi Li
> Attachments: MAPREDUCE-4815.v3.patch, MAPREDUCE-4815.v4.patch,
> MAPREDUCE-4815.v5.patch, MAPREDUCE-4815.v6.patch, MAPREDUCE-4815.v7.patch,
> MAPREDUCE-4815.v8.patch
>
>
> If a job generates many files to commit then the commitJob method call at the
> end of the job can take minutes. This is a performance regression from 1.x,
> as 1.x had the tasks commit directly to the final output directory as they
> were completing and commitJob had very little to do. The commit work was
> processed in parallel and overlapped the processing of outstanding tasks. In
> 0.23/2.x, the commit is single-threaded and waits until all tasks have
> completed before commencing.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
