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https://issues.apache.org/jira/browse/HDFS-4972?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13709723#comment-13709723
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Hudson commented on HDFS-4972:
------------------------------
UNSTABLE: Integrated in Hadoop-Hdfs-0.23-Build #670 (See
[https://builds.apache.org/job/Hadoop-Hdfs-0.23-Build/670/])
HDFS-4972. Permission check and operation are done in a separate lock for
getBlockLocations(). Contributed by Kihwal Lee. (kihwal:
http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1503461)
*
/hadoop/common/branches/branch-0.23/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
*
/hadoop/common/branches/branch-0.23/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
> [branch-0.23] permission check and operation are done in a separate lock for
> getBlockLocations()
> ------------------------------------------------------------------------------------------------
>
> Key: HDFS-4972
> URL: https://issues.apache.org/jira/browse/HDFS-4972
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: namenode
> Affects Versions: 0.23.8
> Reporter: Kihwal Lee
> Assignee: Kihwal Lee
> Fix For: 0.23.10
>
> Attachments: HDFS-4972-branch-0.23.patch
>
>
> For getBlockLocations() call, the read lock is acquired when doing permission
> check. But unlike other namenode methods, this is outside of the lock of the
> actual operation. So it ends up acquiring and releasing the lock twice. This
> has two implications.
> - permissions can change in between the locks
> - the lock fairness will penalize getBlockLocations().
> This was fixed in trunk and branch-2 as a part of HDFS-4679, but not in
> branch-0.23.
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