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From "Suresh Srinivas (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-6967) DNs may OOM under high webhdfs load
Date Thu, 04 Sep 2014 22:10:24 GMT

    [ https://issues.apache.org/jira/browse/HDFS-6967?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14122071#comment-14122071
] 

Suresh Srinivas commented on HDFS-6967:
---------------------------------------

[~daryn], is this because some of the blocks are popular?

Also is there anyway the datanode load (number of xceivers assuming the local DFSClient access
for webhdfs is counted towards load) can be factored into redirecting?

> DNs may OOM under high webhdfs load
> -----------------------------------
>
>                 Key: HDFS-6967
>                 URL: https://issues.apache.org/jira/browse/HDFS-6967
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: datanode, webhdfs
>    Affects Versions: 2.0.0-alpha, 3.0.0
>            Reporter: Daryn Sharp
>            Assignee: Eric Payne
>
> Webhdfs uses jetty.  The size of the request thread pool is limited, but jetty will accept
and queue infinite connections.  Every queued connection is "heavy" with buffers, etc.  Unlike
data streamer connections, thousands of webhdfs connections will quickly OOM a DN.  The accepted
requests must be bounded and excess clients rejected so they retry on a new DN.



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