[ https://issues.apache.org/jira/browse/MAPREDUCE-5791?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Nikola Vujic updated MAPREDUCE-5791: ------------------------------------ Attachment: MAPREDUCE-5791.patch > 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 > Reporter: Nikola Vujic > Assignee: Nikola Vujic > Attachments: 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)