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Posted to common-issues@hadoop.apache.org by "Lei (Eddy) Xu (JIRA)" <ji...@apache.org> on 2014/06/26 19:23:27 UTC

[jira] [Updated] (HADOOP-10755) Support negative caching of user-group mapping

     [ https://issues.apache.org/jira/browse/HADOOP-10755?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Lei (Eddy) Xu updated HADOOP-10755:
-----------------------------------

    Attachment: HADOOP-10755.000.patch

This patch changes default value of negative cache timeout to 30 seconds. Also it changes the configuration key of negative cache timeout as "negative-cache.secs".

[~vinayrpet] Thank you for the comments! I have one more question: should negative cache be enabled by default?

> 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, 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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