[ http://issues.apache.org/jira/browse/HADOOP-752?page=all ]
Doug Cutting updated HADOOP-752:
--------------------------------
Status: Resolved (was: Patch Available)
Fix Version/s: 0.10.0
Resolution: Fixed
I just committed this. Thanks, Dhruba!
> Possible locking issues in HDFS Namenode
> ----------------------------------------
>
> Key: HADOOP-752
> URL: http://issues.apache.org/jira/browse/HADOOP-752
> Project: Hadoop
> Issue Type: Bug
> Components: dfs
> Reporter: dhruba borthakur
> Assigned To: dhruba borthakur
> Fix For: 0.10.0
>
> Attachments: namenodelocking.patch
>
>
> I have been investigating the cause of random Namenode memory
> corruptions/memory overflows, etc. Please comment.
> 1. The functions datanodeReport() and DFSNodesStatus() do not acquire the
> global lock.
> This can race with another thread invoking registerDatanode().
> registerDatanode()
> can remove a datanode (thru wipeDatanode()) while the datanodeReport
> thread is
> traversing the list of datanodes. This can cause exceptions to occur.
> 2. The blocksMap is protected by the global lock. The setReplication() call
> does not acquire
> the global lock when it calls proccessOverReplicatedBlock(). This can
> cause corruption in blockMap.
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