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From "Daryn Sharp (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HDFS-5681) renewLease should not hold fsn write lock
Date Wed, 18 Dec 2013 16:14:07 GMT

     [ https://issues.apache.org/jira/browse/HDFS-5681?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Daryn Sharp updated HDFS-5681:
------------------------------

    Attachment: HDFS-5681.patch

I believe the change is truly as simple as changing to a read lock.

The lease manager methods are synchronized and other callers into the lease manager are under
the write lock.  My main concern was issues with the lease monitor thread but it too is acquiring
the fsn write lock.  There should not be race conditions.

> renewLease should not hold fsn write lock
> -----------------------------------------
>
>                 Key: HDFS-5681
>                 URL: https://issues.apache.org/jira/browse/HDFS-5681
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: namenode
>    Affects Versions: 2.0.0-alpha, 3.0.0
>            Reporter: Daryn Sharp
>         Attachments: HDFS-5681.patch
>
>
> Lease renewals unnecessarily hold the write lock which reduces throughput.  Currently
the fsn lock doubles as an "operational lock" to prevent state transitions.  If the lease
manager is thread-safe then a read lock is sufficient.



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