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https://issues.apache.org/jira/browse/HADOOP-10755?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Lei (Eddy) Xu updated HADOOP-10755:
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Attachment: HADOOP-10755.003.patch
Thanks [~andrew.wang] for your suggestions! They are very helpful because they
clarify a few requirements for me. I've updated the patch accordingly.
Btw, to remove the racy code (e.g., relying on system time for cache
expiration), I added a {{FakeTimer}} to do the dependency injections, which,
along with a new {{Timer}} class, has similar signatures to the static utility
class {{Time}}.
> 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, HADOOP-10755.003.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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