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Posted to common-issues@hadoop.apache.org by "Jason Lowe (JIRA)" <ji...@apache.org> on 2014/01/29 21:22:16 UTC

[jira] [Updated] (HADOOP-9749) Remove synchronization for UGI.getCurrentUser

     [ https://issues.apache.org/jira/browse/HADOOP-9749?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jason Lowe updated HADOOP-9749:
-------------------------------

    Target Version/s: 3.0.0, 0.23.11, 2.4.0  (was: 3.0.0, 0.23.11)

> Remove synchronization for UGI.getCurrentUser
> ---------------------------------------------
>
>                 Key: HADOOP-9749
>                 URL: https://issues.apache.org/jira/browse/HADOOP-9749
>             Project: Hadoop Common
>          Issue Type: Sub-task
>          Components: security
>    Affects Versions: 0.23.0, 2.0.0-alpha, 3.0.0
>            Reporter: Daryn Sharp
>            Assignee: Daryn Sharp
>            Priority: Critical
>
> HADOOP-7854 added synchronization to {{getCurrentUser}} due to {{ConcurrentModificationExceptions}}.  This degrades NN call handler performance.
> The problem was not well understood at the time, but it's caused by a collision between relogin and {{getCurrentUser}} due to a bug in {{Krb5LoginModule}}.  Avoiding the collision will allow removal of the synchronization.



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