When are isolated workers classloaders garbage collected?

// This creates a new classloader, is it GC'd at the end of the work if nothing else keeps a reference?
      val workQueue = getWorkerExecutor().classLoaderIsolation { workerSpec ->
        workerSpec.classpath.from(classpath)
      }

I think you are hitting something like https://github.com/gradle/gradle/issues/18313. They get GCed after next build afaik. It's a bug or at least something that needs an improvement

Thanks! They keep adding up though so looks like I have another leak.... In heap dumps, I can see some classloaders have no GC root but are still around 🤔

Process isolation doesn't have this problem since classes are loaded in a different process and process stops after the build

Yea I guess it’s just a workaround... Still curious what the real issue is

From internal conversation:

Classloader reuse for classloader isolation has always been something that we planned to implement, but was de-prioritized before we got around to it. The caching of the generated work classes was added later and it seems it was never clear the effect this had on these classloader isolated work items. This creates the worst of both worlds (i.e. caching stuff that is never reused).

So basically there is some caching involved to reuse classloaders, but it's not effective and have negative consequences.

For now, I'll expose the option to the user but it's not great as they have to choose between memory leaks or longer fork times.