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https://issues.apache.org/jira/browse/HDFS-3990?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13477909#comment-13477909
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Daryn Sharp commented on HDFS-3990:
-----------------------------------
In your patch, it's not necessary for the NN to do another lookup of the DN's
hostname. It's already available in the {{InetAddress}} returned by
{{Server.getRemoteIp()}}. Passing this {{InetAddress}} to {{updateNodeAddr}},
rather than individually update the hostname and ip ensures the host and ip are
always updated in tandem to avoid your concern about the fields going out of
sync.
If we do change the datanode manager to ignore the hostname in the node
registration, do you think it's possible to update all the tests that check
rack placement? I'm not sure how we can do that in a timely manner, so would
you be willing to have a separate jira for that functional change to expedite
this compatible one?
> 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.patch,
> HDFS-3990.patch, hdfs-3990.txt, 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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