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https://issues.apache.org/jira/browse/HDFS-6648?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14099918#comment-14099918
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Harsh J commented on HDFS-6648:
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I don't think it was the design goal to have them being connected to in any
order of configuration; just based off a list in the configuration.
Is this posing a Major problem for you though? The proxy is invoked only during
init and trouble within an instance, not at every request.
> Order of namenodes in ConfiguredFailoverProxyProvider is not defined by order
> in hdfs-site.xml
> ----------------------------------------------------------------------------------------------
>
> Key: HDFS-6648
> URL: https://issues.apache.org/jira/browse/HDFS-6648
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: ha, hdfs-client
> Affects Versions: 2.2.0
> Reporter: Rafal Wojdyla
>
> In org.apache.hadoop.hdfs.server.namenode.ha.ConfiguredFailoverProxyProvider,
> in the constructor, there's a map <nameservice : < service-id :
> service-rpc-address > > (DFSUtil.getHaNnRpcAddresses). It's a LinkedHashMap
> of HashMaps. The order is kept for _nameservices_. Then to find active
> namenode, for nameservice, we get HashMap of <service-id :
> service-rpc-address > for requested nameservice (taken from URI request), And
> for this HashMap we get values - order of this collection is not strictly
> defined! In the code:
> {code}
> Collection<InetSocketAddress> addressesOfNns = addressesInNN.values();
> {code}
> And then we put these values (in not defined order) into ArrayList of
> proxies, and then in getProxy we start from first proxy in the list and
> failover to next if needed.
> It would make sense for ConfiguredFailoverProxyProvider to keep order of
> proxies/namenodes defined in hdfs-site.xml.
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