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https://issues.apache.org/jira/browse/HDFS-9198?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14987330#comment-14987330
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Daryn Sharp commented on HDFS-9198:
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# I named it more generically since it can be used for more, but I'll rename if
you feel strongly.
# I originally had it outside the loop but something failed. Probably a test.
Since it's a class static it should be cheap.
# The NN is terminated when the queue stops accepting offers and the thread
isn't running, but I'll add a try/catch around the run() loop too.
# Will look at the style again.
# Yes, I compensated for async IBR failures by making the next heartbeat
trigger a re-registration. The only exception we've seen from an IBR is
dead/unregistered node so the new code is a no-op but I added it as a safety
net.
# Ok.
> 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,
> HDFS-9198-trunk.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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