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From "Suresh Srinivas (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-4466) Remove the deadlock from AbstractDelegationTokenSecretManager
Date Tue, 12 Feb 2013 18:37:12 GMT

    [ https://issues.apache.org/jira/browse/HDFS-4466?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13576865#comment-13576865
] 

Suresh Srinivas commented on HDFS-4466:
---------------------------------------

+1 for the patch.
                
> Remove the deadlock from AbstractDelegationTokenSecretManager
> -------------------------------------------------------------
>
>                 Key: HDFS-4466
>                 URL: https://issues.apache.org/jira/browse/HDFS-4466
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: namenode, security
>    Affects Versions: 1.2.0
>            Reporter: Brandon Li
>            Assignee: Brandon Li
>         Attachments: HDFS-4466.branch-1.patch
>
>
> In HDFS-3374, new synchronization in AbstractDelegationTokenSecretManager.ExpiredTokenRemover
was added to make sure the ExpiredTokenRemover thread can be interrupted in time. Otherwise
TestDelegation fails intermittently because the MiniDFScluster thread could be shut down before
tokenRemover thread. 
> However, as Todd pointed out in HDFS-3374, a potential deadlock was introduced by its
patch:
> {quote}
>    * FSNamesystem.saveNamespace (holding FSN lock) calls DTSM.saveSecretManagerState
(which takes DTSM lock)
>    * ExpiredTokenRemover.run (holding DTSM lock) calls rollMasterKey calls updateCurrentKey
calls logUpdateMasterKey which takes FSN lock
> So if there is a concurrent saveNamespace at the same tie as the expired token remover
runs, it might make the NN deadlock. {quote}
> This JIRA is to track the change of removing the possible deadlock from AbstractDelegationTokenSecretManager.


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