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From "Amruth Sampath (Jira)" <j...@apache.org>
Subject [jira] [Comment Edited] (HIVE-22165) Synchronisation introduced by HIVE-14296 on SessionManager.closeSession causes high latency in a busy hive server
Date Wed, 01 Jan 2020 14:32:00 GMT

    [ https://issues.apache.org/jira/browse/HIVE-22165?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17006417#comment-17006417
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Amruth Sampath edited comment on HIVE-22165 at 1/1/20 2:31 PM:
---------------------------------------------------------------

Hi [~gopalv], [~rajesh.balamohan], Kindly let me know if I have to do anything more to get
this in. Your help is much appreciated. Thanks in advance) not found.


was (Author: amrk7):
Hi [~gopalv], [~rajesh.balamohan]!, Kindly let me know if I have to do anything more to get
this in. Your help is much appreciated. Thanks in advance!

> Synchronisation introduced by HIVE-14296 on SessionManager.closeSession causes high latency
in a busy hive server
> -----------------------------------------------------------------------------------------------------------------
>
>                 Key: HIVE-22165
>                 URL: https://issues.apache.org/jira/browse/HIVE-22165
>             Project: Hive
>          Issue Type: Bug
>          Components: HiveServer2
>    Affects Versions: 2.1.0, 2.3.2
>            Reporter: Amruth Sampath
>            Assignee: Amruth Sampath
>            Priority: Major
>         Attachments: HIVE-22165.patch, HIVE-22165.patch.1
>
>
> HIVE-14296 introduces this [commit|https://github.com/apache/hive/commit/477a47d3b4b9e3da3c22465217c2024588f7f000] which
adds synchronization to SessionManager.closeSession.
> And it looks like it is used only for logging purposes.
> In a busy hive server where 5-10 sessions are created closed every second, an increase
in latency of any other downstream services (Zk, HDFS) causes a queueing effect (lot of threads
getting blocked on SessionManager.closeSession) creating an induced latency of 3-5 minutes
at times for just closing the session. 
> Since the gauge (MetricsConstant.HS2_OPEN_SESSIONS) is already tracking the open session
counts, the synchronization (along with the additional logging) can be removed without any
functionality losses.



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