[ https://issues.apache.org/jira/browse/HADOOP-7854?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13160863#comment-13160863 ] 

Hudson commented on HADOOP-7854:
--------------------------------

Integrated in Hadoop-Hdfs-0.23-Build #94 (See [https://builds.apache.org/job/Hadoop-Hdfs-0.23-Build/94/])
    Merged r1208926 from trunk for HADOOP-7854.

jitendra : http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1208929
Files : 
* /hadoop/common/branches/branch-0.23/hadoop-common-project/hadoop-common/CHANGES.txt
* /hadoop/common/branches/branch-0.23/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/UserGroupInformation.java

                
> UGI getCurrentUser is not synchronized
> --------------------------------------
>
>                 Key: HADOOP-7854
>                 URL: https://issues.apache.org/jira/browse/HADOOP-7854
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: security
>    Affects Versions: 1.0.0
>            Reporter: Daryn Sharp
>            Assignee: Daryn Sharp
>            Priority: Critical
>             Fix For: 0.23.1, 1.0.0
>
>         Attachments: HADOOP-7854-trunk.patch, HADOOP-7854.patch
>
>
> Sporadic {{ConcurrentModificationExceptions}} are originating from {{UGI.getCurrentUser}} when it needs to create a new instance.  The problem was specifically observed in a JT under heavy load when a post-job cleanup is accessing the UGI while a new job is being processed.

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