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From "Andrew Wang (JIRA)" <j...@apache.org>
Subject [jira] [Assigned] (HDFS-5369) Support negative caching of user-group mapping
Date Wed, 16 Oct 2013 17:11:45 GMT

     [ https://issues.apache.org/jira/browse/HDFS-5369?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Andrew Wang reassigned HDFS-5369:
---------------------------------

    Assignee: Andrew Wang

> 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: Andrew Wang
>
> 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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