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https://issues.apache.org/jira/browse/HDDS-2199?focusedWorklogId=321936&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-321936
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ASF GitHub Bot logged work on HDDS-2199:
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Author: ASF GitHub Bot
Created on: 02/Oct/19 14:33
Start Date: 02/Oct/19 14:33
Worklog Time Spent: 10m
Work Description: sodonnel commented on pull request #1551: HDDS-2199 In
SCMNodeManager dnsToUuidMap cannot track multiple DNs on the same host
URL: https://github.com/apache/hadoop/pull/1551#discussion_r330585159
##########
File path:
hadoop-hdds/server-scm/src/main/java/org/apache/hadoop/hdds/scm/server/SCMBlockProtocolServer.java
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@@ -295,7 +297,33 @@ public ScmInfo getScmInfo() throws IOException {
boolean auditSuccess = true;
try{
NodeManager nodeManager = scm.getScmNodeManager();
- Node client = nodeManager.getNodeByAddress(clientMachine);
Review comment:
Looking at where sortDatanodes() is used, it seems to be from the OM when
performing lookup file or lookup key. So that suggests it is only used in the
read path, and hence at most 3 DNs should be passed in along with one client
address.
The code could be simplified a little, but I think we do need to filter the
list of returned nodes down to only the nodes it cares about due to what I said
in the comment above.
However, thinking about this some more, I think we can avoid the random
selection. In the case where there is only 1 DN per host, the DN matching the
client would always be sorted first, so we don't really need to randomize the
first node returned if all nodes are on the same host. I will refactor this and
see how it looks then.
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Issue Time Tracking
-------------------
Worklog Id: (was: 321936)
Time Spent: 2h 50m (was: 2h 40m)
> 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
> Assignee: Stephen O'Donnell
> Priority: Major
> Labels: pull-request-available
> Time Spent: 2h 50m
> Remaining Estimate: 0h
>
> 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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