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Posted to issues@hive.apache.org by "Rajesh Balamohan (Jira)" <ji...@apache.org> on 2020/02/07 08:06:00 UTC
[jira] [Comment Edited] (HIVE-22850) Optimise lock acquisition in
TxnHandler
[ https://issues.apache.org/jira/browse/HIVE-22850?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17032185#comment-17032185 ]
Rajesh Balamohan edited comment on HIVE-22850 at 2/7/20 8:05 AM:
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For ref: Lock interaction matrix: https://issues.apache.org/jira/secure/attachment/12614488/HiveTransactionManagerDetailedDesign%20%281%29.pdf (Page 8)
was (Author: rajesh.balamohan):
Lock interaction matrix: https://issues.apache.org/jira/secure/attachment/12614488/HiveTransactionManagerDetailedDesign%20%281%29.pdf (Page 8)
> Optimise lock acquisition in TxnHandler
> ---------------------------------------
>
> Key: HIVE-22850
> URL: https://issues.apache.org/jira/browse/HIVE-22850
> Project: Hive
> Issue Type: Improvement
> Components: Hive
> Reporter: Rajesh Balamohan
> Priority: Major
> Attachments: HIVE-22850.1.patch, Screenshot 2020-02-07 at 4.14.51 AM.png
>
>
> With concurrent queries, time taken for lock acquisition increases substantially. As part of lock acquisition in the query, {{TxnHandler::checkLock}} gets invoked. This involves getting a mutex and compare the locks being requested for, with that of existing locks in {{HIVE_LOCKS}} table.
> With concurrent queries, time taken to do this check increase and this significantly increases the time taken for getting mutex for other threads (due to select for update). In a synthetic workload, it was in the order of 10+ seconds. This codepath can be optimized when all lock requests are SHARED_READ.
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