[FLINK-17554] Add release hooks for user code class loader

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.11.0
• Fix Version/s: 1.12.0
• Component/s: Runtime / Coordination
• Labels: pull-request-available
• Assignee: Robert Metzger
• Reporter: Till Rohrmann
• Created: 07/May/20 10:06
• Updated: 16/Sep/20 07:27
• Resolved: 16/Sep/20 07:25

Description

Release hooks for the user code class loader which are run just before the user code class loader is released would allow clean up static references to classes of the user code class loader. This is important because these static references could prevent the user code classes from being garbage collected and eventually causing metaspace OOMs.

Hence I suggest to extend the RuntimeContext with an additional method registerUserCodeClassLoaderReleaseHook(Runnable releaseHook) which allows the user code to register a release hook for the user code class loader.

Issue Links

• is related to: FLINK-16246 Exclude "SdkMBeanRegistrySupport" from dynamically loaded AWS connectors
• relates to: FLINK-19259 Use classloader release hooks with Kinesis producer to avoid metaspace leak
• links to: GitHub Pull Request #12026
• links to: GitHub Pull Request #13355
• links to: Steps to reproduce