> but goroutine B (the goroutineB function) apparently never ran at all. Untrue. Up the iterations to 1000, you'll get your interleaving. Since 1.14, goroutine

> but goroutine B (the goroutineB function) apparently never ran at all. Untrue. Up the iterations to 1000, you'll get your interleaving. Since 1.14, goroutines are async preemptible (async safe points), and will not block the scheduler. Also, time.Sleep bad, use runtime.Gosched().