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From "Gopal V (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-16979) Cache UGI for metastore
Date Wed, 28 Jun 2017 04:58:00 GMT

    [ https://issues.apache.org/jira/browse/HIVE-16979?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16065927#comment-16065927
] 

Gopal V commented on HIVE-16979:
--------------------------------

[~taoli-hwx]:  Does Guava's cache track the life time of a cache object? Will this code cause
a race condition if the cache expires while a query is using this UGI?

> 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
>
>
> 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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