[jira] [Commented] (HADOOP-10077) o.a.h.s.Groups should refresh in the background

["Chris Nauroth (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-10077?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14212650#comment-14212650 ] 

Chris Nauroth commented on HADOOP-10077:
----------------------------------------

I linked this to HADOOP-11238, which seems to be addressing a similar problem.

> o.a.h.s.Groups should refresh in the background
> -----------------------------------------------
>
>                 Key: HADOOP-10077
>                 URL: https://issues.apache.org/jira/browse/HADOOP-10077
>             Project: Hadoop Common
>          Issue Type: Bug
>    Affects Versions: 2.3.0
>            Reporter: Colin Patrick McCabe
>            Assignee: Colin Patrick McCabe
>         Attachments: HADOOP-10077.001.patch
>
>
> {{org.apache.hadoop.security.Groups}} maintains a cache of mappings between user names and sets of associated group names.  Periodically, the entries in this cache expire and must be refetched from the operating system.
> Currently, this is done in the context of whatever thread happens to try to access the group mapping information right after the time period expires.  However, this is problematic, since that thread may be holding the {{FSNamesystem}} lock.  This means that if the {{GroupMappingServiceProvider}} is slow, the whole NameNode may grind to a halt until it finishes.  This can generate periodic load spikes or even NameNode failovers.
> Instead, we should allow the refreshing of the group mappings to be done asynchronously in a background thread pool.



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)