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https://issues.apache.org/jira/browse/HADOOP-8088?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13231394#comment-13231394
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Kihwal Lee commented on HADOOP-8088:
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We use a refresh cycle of 4 hrs. It becomes a serious issue when headless users
associated with tight SLA jobs get in there. This behavior is not a
hypothetical one. We've seen this in production.
I do agree with you on the problem of having too many configs, but we often end
up going this route in (sometimes justifiable) fear of breaking compatibility
even if the bug is clearly there and in need of fix. I would appreciate your
further input on how we can address the issue with the minimum negative impact.
> User-group mapping cache incorrectly does negative caching on transient
> failures
> --------------------------------------------------------------------------------
>
> Key: HADOOP-8088
> URL: https://issues.apache.org/jira/browse/HADOOP-8088
> Project: Hadoop Common
> Issue Type: Bug
> Components: security
> Affects Versions: 0.20.205.0, 0.24.0, 0.23.1, 1.0.0, 1.1.0
> Reporter: Kihwal Lee
> Fix For: 0.24.0, 1.1.0, 0.23.2
>
> Attachments: hadoop-8088-branch-1.patch, hadoop-8088-trunk.patch,
> hadoop-8088-trunk.patch
>
>
> We've seen a case where some getGroups() calls fail when the ldap server or
> the network is having transient failures. Looking at the code, the
> shell-based and the JNI-based implementations swallow exceptions and return
> an empty or partial list. The caller, Groups#getGroups() adds this likely
> empty list into the mapping cache for the user. This will function as
> negative caching until the cache expires. I don't think we want negative
> caching here, but even if we do, it should be intelligent enough to
> distinguish transient failures from ENOENT. The log message in the jni-based
> impl also needs an improvement. It should print what exception it encountered
> instead of just saying one happened.
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