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Posted to common-issues@hadoop.apache.org by "Kihwal Lee (Updated) (JIRA)" <ji...@apache.org> on 2012/02/17 23:20:57 UTC
[jira] [Updated] (HADOOP-8088) User-group mapping cache incorrectly
does negative caching on transient failures
[ https://issues.apache.org/jira/browse/HADOOP-8088?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Kihwal Lee updated HADOOP-8088:
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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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