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Posted to issues@kylin.apache.org by "Guangyuan Feng (Jira)" <ji...@apache.org> on 2023/06/14 02:28:00 UTC
[jira] [Resolved] (KYLIN-5545) Try best to interrupt running queries and limit the number of queries to run
[ https://issues.apache.org/jira/browse/KYLIN-5545?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Guangyuan Feng resolved KYLIN-5545.
-----------------------------------
Resolution: Fixed
> Try best to interrupt running queries and limit the number of queries to run
> ----------------------------------------------------------------------------
>
> Key: KYLIN-5545
> URL: https://issues.apache.org/jira/browse/KYLIN-5545
> Project: Kylin
> Issue Type: Bug
> Components: Query Engine
> Affects Versions: 5.0-alpha
> Reporter: Guangyuan Feng
> Assignee: fanfanAlice
> Priority: Major
> Fix For: 5.0-beta
>
>
> *Issues*
> There are two issues will decrease the stability of Kylin:
> # Missed some places to cancel the planning/running queries if occurred interruptions, leading to the useless consumptions of calculating resources.
> # Don't limit the number of queries that can be pushed down, leading to too many queries to run, evenly to a OOM.
> So it's great to have a PR to improve/solve the above issues.
>
> *Proposal changes*
> # Add a new property {{kylin.query.pushdown-concurrent-running-threshold=10}} to control the concurrency of the queries pushed down, 10 running queries by default, which will be bond to a Semaphore instance in JVM scope.
> # The pushed down query will calling {{Semaphore}} instance's {{tryAcquire(long timeout, TimeUnit unit)}} to acquire the chance to run, so the waiting queries could be interrupted if failed in {{330s}} by default.
>
> *Why changes*
> # {{QueryLimiter}} won't working then the server is not in {{downgrade}} state, which means no limitations on the number of queries pushed down to run, therefore we need another strategy to accomplish the goal.
> # During retrieving the file status, it gives us a chance to react to the interruption, so as to terminate the planning queries.
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