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From "Benoy Antony (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-10590) ServiceAuthorizationManager is not threadsafe
Date Mon, 19 May 2014 17:38:38 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-10590?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14002041#comment-14002041
] 

Benoy Antony commented on HADOOP-10590:
---------------------------------------

We had a an error where authorization policy checks returned inconsistent results on a  cluster.
Looking at the code , that inconsistency is possible due to the visibility issues of  the
code. 

As you commented,  there is a cost  for volatile  vs non-volatile. The performance of volatile
depends heavily on the CPU architecture . http://stackoverflow.com/questions/4633866/is-volatile-expensive
.

I'll  try benchmarking the change, but not sure if that's very useful since performance of
volatile varies wildly across CPU architectures. I believe, the main decision will be correctness
vs performance.


> ServiceAuthorizationManager  is not threadsafe
> ----------------------------------------------
>
>                 Key: HADOOP-10590
>                 URL: https://issues.apache.org/jira/browse/HADOOP-10590
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: security
>    Affects Versions: 2.4.0
>            Reporter: Benoy Antony
>            Assignee: Benoy Antony
>         Attachments: HADOOP-10590.patch
>
>
> The mutators in ServiceAuthorizationManager  are synchronized. The accessors are not
synchronized.
> This results in visibility issues when  ServiceAuthorizationManager's state is accessed
from different threads.



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