[
https://issues.apache.org/jira/browse/MAPREDUCE-5791?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13959944#comment-13959944
]
Nikola Vujic commented on MAPREDUCE-5791:
-----------------------------------------
I missed to format the table. Here it is:
|| ||Elapsed||Avg Map Time||Avg Reduce time||Avg Shuffle Time||Avg Merge Time||
|default|3194.67|402.33|248.67|1471.33|12.33|
|optimized shuffle|2411.00|392.00|689.67|674.67|17.17|
|default/optmized|1.33|1.03|0.36|2.18|0.72|
> 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
> Fix For: 3.0.0, 2.4.0
>
> 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.
--
This message was sent by Atlassian JIRA
(v6.2#6252)
