[jira] [Commented] (YARN-4353) Provide short circuit user group mapping for NM/AM

["Daniel Templeton (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/YARN-4353?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15003009#comment-15003009 ] 

Daniel Templeton commented on YARN-4353:
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Looks like I don't have permission to assign this to myself yet...  In the meantime, I'm working on a patch.

> Provide short circuit user group mapping for NM/AM
> --------------------------------------------------
>
>                 Key: YARN-4353
>                 URL: https://issues.apache.org/jira/browse/YARN-4353
>             Project: Hadoop YARN
>          Issue Type: Improvement
>          Components: nodemanager
>    Affects Versions: 2.7.1
>            Reporter: Daniel Templeton
>
> When the NM launches an AM, the {{ContainerLocalizer}} gets the current user from {{UserGroupInformation}}, which triggers user group mapping, even though the user groups are never accessed.  If secure LDAP is configured for group mapping, then there are some additional complications created by the unnecessary group resolution.  Additionally, it adds unnecessary latency to the container launch time.
> To address the issue, before getting the current user, the {{ContainerLocalizer}} should configure {{UserGroupInformation}} with a null group mapping service that quickly and quietly returns an empty group list for all users.



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