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From "Brandon Li (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-4466) Remove the deadlock from AbstractDelegationTokenSecretManager
Date Tue, 05 Feb 2013 19:00:12 GMT

    [ https://issues.apache.org/jira/browse/HDFS-4466?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13571593#comment-13571593

Brandon Li commented on HDFS-4466:

Test-patch result:
-1 overall.  
    +1 @author.  The patch does not contain any @author tags.
    +1 tests included.  The patch appears to include 3 new or modified tests.
    +1 javadoc.  The javadoc tool did not generate any warning messages.
    +1 javac.  The applied patch does not increase the total number of javac compiler warnings.
    -1 findbugs.  The patch appears to introduce 208 new Findbugs (version 2.0.0) warnings.

The patch doesn't introduce new findbugs warning.

> 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
> {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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