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From "Daniel Dai (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HIVE-16979) Cache UGI for metastore
Date Wed, 13 Jun 2018 22:59:01 GMT

    [ https://issues.apache.org/jira/browse/HIVE-16979?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16511753#comment-16511753
] 

Daniel Dai commented on HIVE-16979:
-----------------------------------

Haven't been tested, the new patch use a different cache strategy. UGI object will not be
evicted if it is still in use. Another change is UGI object will not be shared across sessions
in case UserGroupInformation and FileSystem is not thread safe. Finished session will release
UGI object in the cache. UGICache will keep the idle object around until eviction.

> 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: Daniel Dai
>            Priority: Major
>         Attachments: HIVE-16979.1.patch, HIVE-16979.2.patch, HIVE-16979.3.patch, HIVE-16979.4.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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