TestClock hangs on parallelism #9385
Description
When using the TestClock, the adjust (or more specifically, run) method synchronizes across fibers to only adjust when the system is at rest. However, due to this checking mechanism, two parallel adjusts will result in a livelock between the two freeze methods.
Reproduction:
import zio.*
import zio.test.*
object Test extends ZIOSpecDefault {
override def spec: Spec[TestEnvironment with Scope, Any] =
test("no problem on sequential calls")(
(TestClock.adjust(1.second) *> TestClock.adjust(1.second)).as(assertCompletes)
) + test("livelock on parallel calls")(
(TestClock.adjust(1.second) &> TestClock.adjust(1.second)).as(assertCompletes)
) @@ TestAspect.timeout(10.seconds)
}