ce w… finished. The code printed executing! twice because our threads share the same @executed variable. Our read (unless @executed) and set (@executed = true) operations are not atomic, meaning that once we read the value it could be changed in other threads before we set a new value.Introduction to Concurrency Models with Ruby. Part I1.3K6exAspArkEnder Ahmet YurtFollowAug 25, 2017 · 1 min readOutput should be one “executing!” Why does output includes two “executing!” in your post?