Possible locking issues in HDFS Namenode
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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
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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