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From "Brandon Li (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HDFS-4466) Remove the deadlock from AbstractDelegationTokenSecretManager
Date Tue, 05 Feb 2013 18:38:11 GMT

     [ https://issues.apache.org/jira/browse/HDFS-4466?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Brandon Li updated HDFS-4466:
-----------------------------

    Description: 
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.


  was:Per discussion in HDFS-3374, this JIRA is to track the change of removing the possible
deadlock from AbstractDelegationTokenSecretManager. 

    
> 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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