hadoop-common-issues mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Daryn Sharp (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-7854) UGI getCurrentUser is not synchronized
Date Wed, 23 Nov 2011 22:56:40 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-7854?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13156371#comment-13156371
] 

Daryn Sharp commented on HADOOP-7854:
-------------------------------------

Good question.  The {{Subject} class appears to generally be thread-safe.  It's internally
synchronizing and using instances such as {{Collections.synchronizedSet}}.  The problem is
due to iterators becoming very grumpy when their collection is modified, and {{Subject}} is
full of collections that can be accessed directly.  I can't find any documentation about whether
{{Subject}} is even supposed to be thread-safe.  I suspect it is once you lock it down as
read-only, but we don't do that.
                
> 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: 0.20.205.1
>            Reporter: Daryn Sharp
>            Assignee: Daryn Sharp
>            Priority: Critical
>         Attachments: 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.

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira

        

Mime
View raw message