Workstealing can lead to deadlocks

[leonard84]

Steps to reproduce

This does not work every time as it is dependent on multiple factors.

• Checkout spockframework/spock@b69f9f1
• run ./gradlew :spock-specs:test --rerun -Dvariant=3.0 -DjavaVersion=21
• You might need to try a few times. This depends a bit on your machine, but if it takes longer than 5m then it is most likely stuck.
• You can attach a debugger to inspect the current executing tests

What is Broken?

As you can see in these two screenshots we switch from executing MockSpecInfoAnnotationSpec to ByteBuddyMockFactoryConcurrentSpec due to workstealing. The problem is that MockSpecInfoAnnotationSpec holds a read-lock for the org.junit.platform.engine.support.hierarchical.ExclusiveResource.GLOBAL_KEY but ByteBuddyMockFactoryConcurrentSpec needs a write-lock.

Context

• Used versions (Jupiter/Vintage/Platform): 5.11.0/5.12.0-SNAPSHOT
• Build Tool/IDE: Gradle

Deliverables

• ...

[leonard84]

Idea: We can use a ThreadLocal to mark which locks are held and then either throw or somehow else reschedule an exclusive task that is incompatible. IIRC this can only happen with the GLOBAL_KEY in the first place, as a lock on a test class forces all children to be executed on the same thread.

[leonard84]