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From "Lei (Eddy) Xu (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-10755) Support negative caching of user-group mapping
Date Wed, 02 Jul 2014 17:53:25 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-10755?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14050481#comment-14050481
] 

Lei (Eddy) Xu commented on HADOOP-10755:
----------------------------------------

Hey, [~andrew.wang] and [~kihwal], could you take another look on this patch? Thanks!

> Support negative caching of user-group mapping
> ----------------------------------------------
>
>                 Key: HADOOP-10755
>                 URL: https://issues.apache.org/jira/browse/HADOOP-10755
>             Project: Hadoop Common
>          Issue Type: Improvement
>          Components: security
>    Affects Versions: 2.2.0
>            Reporter: Andrew Wang
>            Assignee: Lei (Eddy) Xu
>         Attachments: HADOOP-10755.000.patch, HADOOP-10755.001.patch, HADOOP-10755.002.patch,
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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