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https://issues.apache.org/jira/browse/HDFS-8865?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14720344#comment-14720344
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Daryn Sharp commented on HDFS-8865:
-----------------------------------
+1 This has made a huge difference, and all the possible style warning were
addressed.
> Improve quota initialization performance
> ----------------------------------------
>
> Key: HDFS-8865
> URL: https://issues.apache.org/jira/browse/HDFS-8865
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: Kihwal Lee
> Assignee: Kihwal Lee
> Attachments: HDFS-8865.patch, HDFS-8865.v2.checkstyle.patch,
> HDFS-8865.v2.patch, HDFS-8865.v3.patch
>
>
> After replaying edits, the whole file system tree is recursively scanned in
> order to initialize the quota. For big name space, this can take a very long
> time. Since this is done during namenode failover, it also affects failover
> latency.
> By using the Fork-Join framework, I was able to greatly reduce the
> initialization time. The following is the test result using the fsimage from
> one of the big name nodes we have.
> || threads || seconds||
> | 1 (existing) | 55|
> | 1 (fork-join) | 68 |
> | 4 | 16 |
> | 8 | 8 |
> | 12 | 6 |
> | 16 | 5 |
> | 20 | 4 |
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