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https://issues.apache.org/jira/browse/HIVE-16979?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16111242#comment-16111242
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Tao Li commented on HIVE-16979:
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Good point. It is used by ThriftBinaryCLIService as well as you mentioned, when
SASL is used with Kerberos for auth. The original motivation was to improve the
latency for remote metastore. Now looks like this change can improve latency
for the HS2 as well (but I did not verify the improvement).
> Cache UGI for metastore
> -----------------------
>
> Key: HIVE-16979
> URL: https://issues.apache.org/jira/browse/HIVE-16979
> Project: Hive
> Issue Type: Improvement
> Reporter: Tao Li
> Assignee: Tao Li
> Attachments: HIVE-16979.1.patch, HIVE-16979.2.patch,
> HIVE-16979.3.patch
>
>
> FileSystem.closeAllForUGI is called per request against metastore to dispose
> UGI, which involves talking to HDFS name node and is time consuming. So the
> perf improvement would be caching and reusing the UGI.
> Per FileSystem.closeAllForUG call could take up to 20 ms as E2E latency
> against HDFS. Usually a Hive query could result in several calls against
> metastore, so we can save up to 50-100 ms per hive query.
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