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https://issues.apache.org/jira/browse/YARN-202?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13492258#comment-13492258
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Hudson commented on YARN-202:
-----------------------------
Integrated in Hadoop-Yarn-trunk #29 (See
[https://builds.apache.org/job/Hadoop-Yarn-trunk/29/])
YARN-202. Log Aggregation generates a storm of fsync() for namenode (Kihwal
Lee via bobby) (Revision 1406269)
Result = SUCCESS
bobby : http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1406269
Files :
* /hadoop/common/trunk/hadoop-yarn-project/CHANGES.txt
*
/hadoop/common/trunk/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-common/src/main/java/org/apache/hadoop/yarn/logaggregation/AggregatedLogFormat.java
> Log Aggregation generates a storm of fsync() for namenode
> ---------------------------------------------------------
>
> Key: YARN-202
> URL: https://issues.apache.org/jira/browse/YARN-202
> Project: Hadoop YARN
> Issue Type: Bug
> Affects Versions: 2.0.2-alpha, 0.23.4
> Reporter: Kihwal Lee
> Assignee: Kihwal Lee
> Priority: Critical
> Fix For: 3.0.0, 2.0.3-alpha, 0.23.5
>
> Attachments: yarn-202.patch
>
>
> When the log aggregation is on, write to each aggregated container log causes
> hflush() to be called. For large clusters, this can creates a lot of fsync()
> calls for namenode.
> We have seen 6-7x increase in the average number of fsync operations compared
> to 1.0.x on a large busy cluster. Over 99% of fsync ops were for log
> aggregation writing to tmp files.
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