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Posted to common-issues@hadoop.apache.org by "Sangjin Lee (JIRA)" <ji...@apache.org> on 2016/05/12 22:28:13 UTC

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

    [ https://issues.apache.org/jira/browse/HADOOP-9749?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15282181#comment-15282181 ] 

Sangjin Lee commented on HADOOP-9749:
-------------------------------------

There has been no movement on this for a while. We'll need to move it out of scope for 2.8.0 soon. Let me know if you disagree.

> 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-alpha1
>            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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