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From "Daryn Sharp (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HDFS-3990) NN's health report has severe performance problems
Date Fri, 12 Oct 2012 19:43:04 GMT

     [ https://issues.apache.org/jira/browse/HDFS-3990?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Daryn Sharp updated HDFS-3990:
------------------------------

    Attachment: HDFS-3990.patch

This is an incremental improvement that caches resolved datanode addrs to prevent multiple
unnecessary dns lookups.  It actually affects more than just the dfshealth page so this should
provide much improved performance. 

I will file another jira for investigating how to get the web page execution out of the namesystem
lock.
                
> 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
>
>
> 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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