[jira] [Commented] (HIVE-16979) Cache UGI for metastore

["Tao Li (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HIVE-16979?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16161807#comment-16161807 ] 

Tao Li commented on HIVE-16979:
-------------------------------

[~gopalv] Thanks for your previous comments. Regarding the liveness issue you mentioned, I don't think it's a concern, given that we keep the cached UGI alive for 24 hours which should be long enough for the queries to complete. Regarding the code path, all the services (including HS2 and metastore) should benefit from the perf gain as long as they involve TUGIAssumingProcessor. Do you have any other comments?

> 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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