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From "Andrew Wang (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HDFS-5369) Support negative caching of user-group mapping
Date Wed, 16 Oct 2013 17:07:44 GMT
Andrew Wang created HDFS-5369:

             Summary: 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

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

Let's consider negative caching of group mapping, as well as quashing the rate of this log

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