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https://issues.apache.org/jira/browse/HADOOP-16047?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16742269#comment-16742269
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Steve Loughran commented on HADOOP-16047:
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I'm going to close this as a duplicate, not because it's not a problem, but
because other people (me) have been complaining about it in the past:
HADOOP-15281
If you can do the work there, I promise I'll do my best to get it in.
A new test case will inevitably be needed in AbstractContractDistCpTest, so
all the stores run it. The S3A specific subclass can maybe use its metrics to
count the #of renames, so check things are working
> Avoid expensive rename when DistCp is writing to S3
> ---------------------------------------------------
>
> Key: HADOOP-16047
> URL: https://issues.apache.org/jira/browse/HADOOP-16047
> Project: Hadoop Common
> Issue Type: Improvement
> Components: fs/s3, tools/distcp
> Reporter: Andrew Olson
> Priority: Major
>
> When writing to an S3-based target, the temp file and rename logic in
> RetriableFileCopyCommand adds some unnecessary cost to the job, as the rename
> operation does a server-side copy + delete in S3 [1]. The renames are
> parallelized across all of the DistCp map tasks, so the severity is mitigated
> to some extent. However a configuration property to conditionally allow
> distributed copies to avoid that expense and write directly to the target
> path would improve performance considerably.
> [1]
> https://github.com/apache/hadoop/blob/release-3.2.0-RC1/hadoop-common-project/hadoop-common/src/site/markdown/filesystem/introduction.md#object-stores-vs-filesystems
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