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https://issues.apache.org/jira/browse/HDFS-9198?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14959448#comment-14959448
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Daryn Sharp commented on HDFS-9198:
-----------------------------------
Most of the test failures are a race condition from IBRs not be sync now. Will
update shortly. All you watchers, any comments on the approach?
> Coalesce IBR processing in the NN
> ---------------------------------
>
> Key: HDFS-9198
> URL: https://issues.apache.org/jira/browse/HDFS-9198
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Affects Versions: 2.0.0-alpha
> Reporter: Daryn Sharp
> Assignee: Daryn Sharp
> Attachments: HDFS-9198-branch2.patch, HDFS-9198-trunk.patch
>
>
> IBRs from thousands of DNs under load will degrade NN performance due to
> excessive write-lock contention from multiple IPC handler threads. The IBR
> processing is quick, so the lock contention may be reduced by coalescing
> multiple IBRs into a single write-lock transaction. The handlers will also
> be freed up faster for other operations.
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