Stephen O'Donnell created HDDS-2199:
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Summary: In SCMNodeManager dnsToUuidMap cannot track multiple DNs
on the same host
Key: HDDS-2199
URL: https://issues.apache.org/jira/browse/HDDS-2199
Project: Hadoop Distributed Data Store
Issue Type: Bug
Affects Versions: 0.5.0
Reporter: Stephen O'Donnell
Often in test clusters and tests, we start multiple datanodes on the same host.
In SCMNodeManager.register() there is a map of hostname -> datanode UUID called
dnsToUuidMap.
If several DNs register from the same host, the entry in the map will be
overwritten and the last DN to register will 'win'.
This means that the method getNodeByAddress() does not return the correct
DatanodeDetails object when many hosts are registered from the same address.
This method is only used in SCMBlockProtocolServer.sortDatanodes() to allow it
to see if one of the nodes matches the client, but it need to be used by the
Decommission code.
Perhaps we could change the getNodeByAddress() method to returns a list of DNs?
In normal production clusters, there should only be one returned, but in test
clusters, there may be many. Any code looking for a specific DN entry would
need to iterate the list and match on the port number too, as host:port would
be the unique definition of a datanode.
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