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https://issues.apache.org/jira/browse/IMPALA-3189?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16990091#comment-16990091
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Todd Lipcon commented on IMPALA-3189:
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This should be largely better with KRPC since we maintain long-running
connections between nodes. Do people still see this issue on the first query
after startup?
> Address scalability issue with N^2 KDC requests on cluster startup
> ------------------------------------------------------------------
>
> Key: IMPALA-3189
> URL: https://issues.apache.org/jira/browse/IMPALA-3189
> Project: IMPALA
> Issue Type: Improvement
> Components: Distributed Exec, Security
> Affects Versions: Impala 2.5.0
> Reporter: Henry Robinson
> Priority: Critical
> Labels: kerberos, scalability
>
> When Impala runs a query that shuffles data amongst all nodes in a
> Kerberos-secured cluster, every node will need to acquire a TGS for every
> other node. In a cluster of 100 nodes or more, this can overwhelm the KDC,
> and queries can exit with an error ("Could not contact KDC for realm").
> A simple workaround is to run a warm-up query until it succeeds (which can
> take a few minutes after cluster startup). The KDC can also be scaled (e.g.
> with secondary KDC nodes).
> Impala can also consider either forcing a TGS request on start-up in a
> staggered fashion, or we can move to recommending SSL + client certificates
> for server<->server communication.
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