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https://issues.apache.org/jira/browse/HDFS-3990?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13477373#comment-13477373
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Daryn Sharp commented on HDFS-3990:
-----------------------------------
Ignoring the hostname the datanode claims to be is blowing up tests that are
checking rack placement. Those tests need to use spoofed hostnames for the
rack mapping.
Prior to the patch, only the include/exclude lists checked the real hostname.
Using the datanode's claimed hostname for the include/exclude checks creates a
security issue, and ignoring the claimed hostname causes tests to fail. I was
fearful that any functional change would break the code, so I'll toss up
another variant of the original patch that keeps the two names separate.
We really need this dns fix, so I think we'll need to break the unified and
proper handling of the dn hostnames to another jira. Agree?
> 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.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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