gharris1727 opened a new pull request, #14177: URL: https://github.com/apache/kafka/pull/14177
The `Classloader.registerAsParallelCapable()` call is intended to be called during static initialization. It must be called prior to the `Classloader` superconstructor, because there it is evaluated to decide whether the classloader instance created will be parallel capable. For the entire lifetime of this test, the `Classloader.registerAsParallelCapable()` call has been in an instance initializer, which is executed after the superconstructor is finished. This has meant that the first `SynchronizedDelegatingClassLoader`, and the first `SynchronizedPluginClassLoader` created have erroneously been non-parallel-capable. However, this test did not flaky-fail until #14089 was merged, because the `SamplingConverter` was never located in the first `SynchronizedPluginClassLoader`. With that PR, the `TestPlugins.pluginPath(TestPlugins.TestPlugin...)` function was changed to return a Set instead of a List. This meant that the `SamplingConverter` then _could_ appear in the first `SynchronizedPluginClassLoader`, and whenever that happened, the test would reproduce a deadlock and fail. Since there was only one `SynchronizedDelegatingClassLoader` created in this test, it was always non-parallel-capable. The test would only deadlock if _both_ classloaders were non-parallel-capable, which was not possible until recently. Importantly, this is only a bug in the test, as the real PluginClassLoader and DelegatingClassLoader have been parallel-capable since they were fixed. ### Committer Checklist (excluded from commit message) - [ ] Verify design and implementation - [ ] Verify test coverage and CI build status - [ ] Verify documentation (including upgrade notes) -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: jira-unsubscr...@kafka.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
