[FLINK-20614] Registered sql drivers not deregistered after task finished in session cluster - ASF JIRA

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Details

Type: Bug
Status: Open
Priority: Not a Priority
Resolution: Unresolved
Affects Version/s: 1.12.0, 1.13.0
Fix Version/s: None
Component/s: Connectors / JDBC, Runtime / Task
Labels:

Description

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 and fixes/circumvents this with JdbcLeakPrevention.

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.