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https://issues.apache.org/jira/browse/HDFS-4972?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Kihwal Lee resolved HDFS-4972.
------------------------------
Resolution: Fixed
Fix Version/s: 0.23.10
Hadoop Flags: Reviewed
> [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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