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https://issues.apache.org/jira/browse/HDFS-5369?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14044201#comment-14044201
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Lei (Eddy) Xu commented on HDFS-5369:
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[~andrew.wang] Thanks for your comments and pointing to the issues raised from
HADOOP-8088. I would consider this patch as reference implementation, so that
it has not yet addressed the error handling of a transient error. I will to
address it as well as SLAs after getting some inputs.
Moreover, the default value for negative cache timeout is still not clear to
me. It might need more field data to support an appropriate timeout value here.
> 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
> Attachments: 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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