Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

Add thread-per-test-class execution model #3941

Open
wants to merge 1 commit into
base: main
Choose a base branch
from
Open

Add thread-per-test-class execution model #3941

wants to merge 1 commit into from

Commits on Aug 31, 2024

  1. Add thread-per-test-class execution model 

    The thread-per-test-class execution model runs tests via one thread per test class. This model is primarily useful in situations when test executions attach `ThreadLocal`s to the test worker thread, which "leak" into other test class executions. This problem can lead to out-of-memory errors, if the `ThreadLocal`s reference (large) object trees, either as its value or via its initial-value `Supplier`, which cannot be cleaned up / garbage collected, because the `ThreadLocal` is referenced by the test worker thread.

The problem becomes even worse, if the test class creates its own class loader and attaches `ThreadLocal`s that reference classes loaded by such class loaders. In such cases the whole class loader including all its loaded classes and (static) state is not eligible for garbage collection, leaking more heap (and non-heap) memory.

Using one thread per test class works around the above problem(s), because once the (ephemeral) thread per test-class finishes, the whole thread and all its `ThreadLocal`s become eligible for garbage collection.

Particularly Quarkus unit tests (`@QuarkusTest` annotated test classes) benefit from this execution model.

This change cannot eliminate other sources of similar leaks, like threads spawned from tests or not removed MBeans. Those kinds of leaks are better handled by the test code or the tested code providing "proper" cleanup mechanisms.

This new execution is implemented via the introduced `ThreadPerClassHierarchicalTestExecutorService`, a 3rd model in addition to `SameThreadHierarchicalTestExecutorService` and `ForkJoinPoolHierarchicalTestExecutorService`. It is enabled if `junit.jupiter.execution.threadperclass.enabled` is set to `true` and `junit.jupiter.execution.parallel.enabled` is `false`.

Issue: junit-team#3939
    @snazy
    snazy committed Aug 31, 2024
    Configuration menu
    Copy the full SHA
    f42e100 View commit details
    Browse the repository at this point in the history