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https://issues.apache.org/jira/browse/HDFS-3990?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13477181#comment-13477181
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Daryn Sharp commented on HDFS-3990:
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bq. I'm not sure re-registering with a new IP and the same storage ID actually
works today.
Jason Lowe recently finished a jira to make that work.
bq. How about we reject the DN registration in case of a DNS hiccup (rather
than use the DN value which the patch currently does in this case)?
I think I'm fine with that, so long as we are more strictly ruling out the
ability to run a cluster in a dns-less or dns error-tolerant environment. I
was considering a second jira that would first scan the include/exclude for the
ip, and if not found, would return include=false or exclude=true if the ip is
unresolved instead of flat out rejecting the node.
Ignoring the name the dn declares is a trivial enough change that do you think
we can just do it in this patch? I was trying to avoid any functional change
with this patch (because who knows what will break!) but I'll post a revised
patch that rejects unresolved and ignores the dn's declared name if that's ok
with you?
> NN's health report has severe performance problems
> --------------------------------------------------
>
> Key: HDFS-3990
> URL: https://issues.apache.org/jira/browse/HDFS-3990
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: name-node
> Affects Versions: 0.23.0, 2.0.0-alpha, 3.0.0
> Reporter: Daryn Sharp
> Assignee: Daryn Sharp
> Priority: Critical
> Attachments: HDFS-3990.patch, HDFS-3990.patch, hdfs-3990.txt
>
>
> The dfshealth page will place a read lock on the namespace while it does a
> dns lookup for every DN. On a multi-thousand node cluster, this often
> results in 10s+ load time for the health page. 10 concurrent requests were
> found to cause 7m+ load times during which time write operations blocked.
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