[ http://issues.apache.org/jira/browse/HADOOP-752?page=comments#action_12454079 ] Raghu Angadi commented on HADOOP-752: -------------------------------------
DFSNodesStatus() locks 'heartBeats' and 'datanodeMap'. As you noted these are not locked in registerDatanode(). I think we should have explicitly stated policy about the locking, which locks are held to protect which state. This will help anyone writing new code or reading the code. > 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 > > 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. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira
