[jira] [Updated] (FLINK-20614) Registered sql drivers not deregistered after task finished in session cluster

["Flink Jira Bot (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-20614?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Flink Jira Bot updated FLINK-20614:
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    Labels: auto-deprioritized-critical stale-major  (was: auto-deprioritized-critical)

I am the [Flink Jira Bot|https://github.com/apache/flink-jira-bot/] and I help the community manage its development. I see this issues has been marked as Major but is unassigned and neither itself nor its Sub-Tasks have been updated for 30 days. I have gone ahead and added a "stale-major" to the issue". If this ticket is a Major, please either assign yourself or give an update. Afterwards, please remove the label or in 7 days the issue will be deprioritized.


> Registered sql drivers not deregistered after task finished in session cluster
> ------------------------------------------------------------------------------
>
>                 Key: FLINK-20614
>                 URL: https://issues.apache.org/jira/browse/FLINK-20614
>             Project: Flink
>          Issue Type: Bug
>          Components: Connectors / JDBC, Runtime / Task
>    Affects Versions: 1.12.0, 1.13.0
>            Reporter: Kezhu Wang
>            Priority: Major
>              Labels: auto-deprioritized-critical, stale-major
>
> {{DriverManager}} keeps registered drivers in its internal data structures which prevents they from gc after task finished. I confirm it in standalone session cluster by observing that {{ChildFirstClassLoader}} could not be reclaimed after several {{GC.run}}, it should exist in all session clusters.
> Tomcat documents [this|https://ci.apache.org/projects/tomcat/tomcat85/docs/jndi-datasource-examples-howto.html#DriverManager,_the_service_provider_mechanism_and_memory_leaks] and fixes/circumvents this with [JdbcLeakPrevention|https://github.com/apache/tomcat/blob/master/java/org/apache/catalina/loader/JdbcLeakPrevention.java#L30].
> Should we solve this in runtime ? Or treat it as connector and clients' responsibility to solve it using {{RuntimeContext.registerUserCodeClassLoaderReleaseHookIfAbsent}} or similar ?
> Personally, it would be nice to solve in runtime as a catch-all to avoid memory-leaking and provide consistent behavior to clients cross per-job and session mode.



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