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https://issues.apache.org/jira/browse/HDFS-15942?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17383264#comment-17383264
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Xiaoqiao He commented on HDFS-15942:
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cherry-pick to branch-3.2.
> Increase Quota initialization threads
> -------------------------------------
>
> Key: HDFS-15942
> URL: https://issues.apache.org/jira/browse/HDFS-15942
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Reporter: Stephen O'Donnell
> Assignee: Stephen O'Donnell
> Priority: Major
> Fix For: 3.3.1, 3.4.0, 3.2.3
>
> Attachments: HDFS-15942.001.patch
>
>
> On large namespaces, the quota initialization at started can take a long time
> with the default 4 threads. Also on NN failover, often the quota needs to be
> calculated before the failover can completed, delaying the failover.
> I performed some benchmarks some time back on a large image (316M inodes 35GB
> on disk), the quota load takes:
> {code}
> quota - 4 threads 39 seconds
> quota - 8 threads 23 seconds
> quota - 12 threads 20 seconds
> quota - 16 threads 15 seconds
> {code}
> As the quota is calculated when the NN is starting up (and hence doing no
> other work) or at failover time before the new standby becomes active, I
> think the quota should use as many threads as possible.
> I proposed we change the default to 8 or 12 on at least trunk and branch-3.3
> so we have a better default going forward.
> Has anyone got any other thoughts?
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