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https://issues.apache.org/jira/browse/HADOOP-10852?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14248117#comment-14248117
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Hudson commented on HADOOP-10852:
---------------------------------

FAILURE: Integrated in Hadoop-Yarn-trunk #777 (See 
[https://builds.apache.org/job/Hadoop-Yarn-trunk/777/])
HADOOP-10852 Fix thread safety issues in NetgroupCache. (Benoy Antony) (benoy: 
rev a095622f36c5e9fff3ec02b14b800038a81f6286)
* 
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/security/NetgroupCache.java


> NetgroupCache is not thread-safe
> --------------------------------
>
>                 Key: HADOOP-10852
>                 URL: https://issues.apache.org/jira/browse/HADOOP-10852
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: security
>    Affects Versions: 2.5.0, 2.4.1
>            Reporter: Benoy Antony
>            Assignee: Benoy Antony
>             Fix For: 2.7.0
>
>         Attachments: HADOOP-10852.patch, HADOOP-10852.patch, 
> HADOOP-10852.patch, HADOOP-10852.patch
>
>
> _NetgroupCache_ internally uses two ConcurrentHashMaps and a boolean variable 
> to signal updates on one of the ConcurrentHashMap
> None of the functions are synchronized  and hence is possible to have 
> unexpected results due to race condition between different threads.
> As an example, consider the following sequence:
> Thread1 :
> {{add}} a group
> {{netgroupToUsersMap}} is updated.
> {{netgroupToUsersMapUpdated}} is set to true.
> Thread 2:
> calls {{getNetgroups}} for a user
> Due to re-ordering, {{netgroupToUsersMapUpdated=true}} is visible, but 
> updates in {{netgroupToUsersMap}} is not visible.
> Does a wrong update with older {{netgroupToUsersMap}} values. 



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