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https://issues.apache.org/jira/browse/HDFS-5369?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14044457#comment-14044457
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Vinayakumar B commented on HDFS-5369:
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Patch looks good.
1. Suggestion is not to use camel case in configuration name.
"negativeCache". It could be split using either '-' or a dot(.). This is inline
with all other configuration names as I have seen in core-default.xml
And for the timeout, I would also prefer 30sec as negative cache timeout
compare to 300sec for normal cache timeout.
Also, This JIRA can be moved to Hadoop Common, since changes are at the Common
side.
> Support negative caching of user-group mapping
> ----------------------------------------------
>
> Key: HDFS-5369
> URL: https://issues.apache.org/jira/browse/HDFS-5369
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Affects Versions: 2.2.0
> Reporter: Andrew Wang
> Assignee: Lei (Eddy) Xu
> Attachments: HDFS-5369.000.patch
>
>
> We've seen a situation at a couple of our customers where interactions from
> an unknown user leads to a high-rate of group mapping calls. In one case,
> this was happening at a rate of 450 calls per second with the shell-based
> group mapping, enough to severely impact overall namenode performance and
> also leading to large amounts of log spam (prints a stack trace each time).
> Let's consider negative caching of group mapping, as well as quashing the
> rate of this log message.
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