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Posted to hdfs-issues@hadoop.apache.org by "Akira Ajisaka (Jira)" <ji...@apache.org> on 2020/09/02 02:54:00 UTC
[jira] [Commented] (HDFS-15555) RBF: Refresh cacheNS when
SocketException occurs
[ https://issues.apache.org/jira/browse/HDFS-15555?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17188943#comment-17188943 ]
Akira Ajisaka commented on HDFS-15555:
--------------------------------------
DFSRouter daemon log when restarting active NameNode: https://gist.github.com/aajisaka/0697a1a62cfd23a9ce7a473ca145c42c
> RBF: Refresh cacheNS when SocketException occurs
> ------------------------------------------------
>
> Key: HDFS-15555
> URL: https://issues.apache.org/jira/browse/HDFS-15555
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: rbf
> Reporter: Akira Ajisaka
> Assignee: Akira Ajisaka
> Priority: Major
>
> Problem:
> When active NameNode is restarted and loading fsimage, DFSRouters significantly slow down.
> Investigation:
> When active NameNode is restarted and loading fsimage, RouterRpcClient receives SocketException. Since RouterRpcClient#isUnavailableException(IOException) returns false when the argument is SocketException, the MembershipNameNodeResolver#cacheNS is not refreshed. That's why the order of the NameNodes returned by MemberShipNameNodeResolver#getNamenodesForNameserviceId(String) is unchanged and the active NameNode is still returned first. Therefore RouterRpcClient still tries to connect to the NameNode that is loading fsimage.
> After loading the fsimage, the NameNode throws StandbyException. The exception is one of the 'Unavailable Exception' and the cacheNS is refreshed.
> Workaround:
> Stop NameNode and wait 1 minute before starting NameNode instead of restarting.
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