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From "Kihwal Lee (Updated) (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HADOOP-8088) User-group mapping cache incorrectly does negative caching on transient failures
Date Fri, 17 Feb 2012 22:20:57 GMT

     [ https://issues.apache.org/jira/browse/HADOOP-8088?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Kihwal Lee updated HADOOP-8088:
-------------------------------

    Description: We've seen a case where some getGroups() calls fail when the ldap server
or the network has a transient issue. Looking the code, the shell-based and the JNI-based
implementation 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.  (was: We've seen a case where some getGroups
calls fail when the ldap server or the network has a transient issue. Looking the code, the
shell-based and the JNI-based implementation 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 cach 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 imple also needs an improvement.
It should print what exception it encountered instead of just saying one happened.)
    
> 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
>
>
> We've seen a case where some getGroups() calls fail when the ldap server or the network
has a transient issue. Looking the code, the shell-based and the JNI-based implementation
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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