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Date: Tue, 5 Feb 2013 19:00:12 +0000 (UTC)
From: "Brandon Li (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
Message-ID: <JIRA.12630580.1359912837698.248055.1360090812876@arcas>
In-Reply-To: <JIRA.12630580.1359912837698@arcas>
References: <JIRA.12630580.1359912837698@arcas>
Subject: [jira] [Commented] (HDFS-4466) Remove the deadlock from
 AbstractDelegationTokenSecretManager
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    [ 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:
{noformat}
-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.
{noformat}

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 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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