[CASSANDRA-19783] In-jvm dtest to detect InstanceClassLoaderLeaks

• Type: Improvement
• Status: Resolved
• Priority: Normal
• Resolution: Fixed
• Fix Version/s: 5.1
• Component/s: Test/dtest/java
• Labels: pull-request-available
• Change Category: Quality Assurance
• Complexity: Normal
• Platform: All

Source Control Link

https://github.com/apache/cassandra/commit/f2c41accf847a4e8eb2529cad0408ff220c40683

Test and Documentation Plan

Modifies ResourceLeakTest to detect new InstanceClassLoader leaks

• Assignee: Doug Rohrer
• Reporter: Doug Rohrer

Authors

Doug Rohrer

Reviewers

Michael Semb Wever

• Created: 18/Jul/24 17:12
• Updated: 17/Sep/24 21:28
• Resolved: 17/Sep/24 21:24

Description

It is currently very easy to add dependencies/code that cause in-jvm dtest InstanceClassLoader leaks, and hard to find them. These patches add a WeakHashSet that allows us to count the number of reachable InstanceClassLoaders in the in-jvm dtest API, so that we can use it in the ResourceLeakTest in the actual Cassandra branches in CI (it only takes 2 iterations to find the leak recently introduced by the inclusion of the oshi.jna  library, which was fixed in https://github.com/apache/cassandra-in-jvm-dtest-api/pull/38)

Notes:

The trunk patch requires the changes made in the in-jvm-dtest-api project in order to compile.

Additionally, ResourceLeakTest#looperEverythingTest (the newly-enabled test) won't fail once we pick up the changes made to include `osha.jna` in the in-jvm-dtest-api project, so I added some "DO NOT COMMIT" code there to prove the test can in fact detect the leak.

 

NOTE: I'm removing the `DO NOT COMMIT` code that demonstrates the test actually fails when there's a leak. If you want to try it out, you can change the line 202 in ResourceLeakTest.java to this: 

 

            try (Cluster cluster = (Cluster) builder.withNodes(numClusterNodes).withConfig(updater)
                    .withSharedClasses(builder.getSharedClasses().and(name -> !name.startsWith("oshi.jna.")))
                    .start())

This removes the `oshi.jna` classes from the shared class loader, which demonstrates the failure.

Issue Links

• is related to: CASSANDRA-19239 jvm-dtests crash on java 17
• links to: GitHub Pull Request #39
• links to: GitHub Pull Request #3429