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https://issues.apache.org/jira/browse/MAPREDUCE-5791?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Chris Nauroth updated MAPREDUCE-5791:
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Component/s: client
Target Version/s: 3.0.0, 2.4.0
Affects Version/s: 3.0.0
2.3.0
Hadoop Flags: Reviewed
+1 for the patch.
Thank you for explaining the edge case around reading the last chunk, and thank
you for adding a comment for it. I'll commit this.
> Shuffle phase is slow in Windows - FadviseFileRegion::transferTo does not
> read disks efficiently
> ------------------------------------------------------------------------------------------------
>
> Key: MAPREDUCE-5791
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-5791
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: client
> Affects Versions: 3.0.0, 2.3.0
> Reporter: Nikola Vujic
> Assignee: Nikola Vujic
> Attachments: MAPREDUCE-5791.patch, MAPREDUCE-5791.patch,
> MAPREDUCE-5791.patch
>
>
> transferTo method in org.apache.hadoop.mapred.FadvisedFileRegion is using
> transferTo method from a FileChannel to transfer data from a disk to socket.
> This is performing slow in Windows, slower than in Linux. The reason is that
> transferTo method for the java.nio is issuing 32K IO requests all the time.
> In Windows, these 32K transfers are not optimal and we don't get the best
> performance form the underlying IO subsystem. In order to achieve better
> performance when reading from the drives, we need to read data in bigger
> chunks, 512K for example.
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