SpringBoot Use virtual threads in OnClassCondition if enabled

Comment From: mhalbritter

I did some benchmarks, where I measured the total time taken in AutoConfigurationImportSelector (which calls OnClassCondition.getOutcomes).

With platform threads, using the spring-boot-smoke-test-actuator, this averages to about 45 ms. With virtual threads, using this code:

private static final class ThreadedOutcomesResolver implements OutcomesResolver {

        private final Future<ConditionOutcome[]> future;

        private ThreadedOutcomesResolver(OutcomesResolver outcomesResolver) {
            VirtualThreadTaskExecutor executor = new VirtualThreadTaskExecutor("OnClassCondition-outcomes-resolver-");
            this.future = executor.submit(outcomesResolver::resolveOutcomes);
        }

        @Override
        public ConditionOutcome[] resolveOutcomes() {
            try {
                return this.future.get();
            }
            catch (InterruptedException | ExecutionException ex) {
                throw new RuntimeException("Failed to resolve outcome", ex);
            }
        }

    }

this averages to about 52 ms.

Switching to virtual threads doesn't give any benefit here.