This was one of my main worries about Go when I evaluated it back in 2010. Most green threads implementations have an explicit determinism model, and it's typically straightforward to reason about and depend on execution order and suchlike, much as you can with plain asynchronous code, but with Go there didn't appear to be any guarantee when or how your code ran.
In any case I suppose many styles of Go program will exhibit accidental determinism, but it still seems too difficult to depend on as randomness can be introduced simply by invoking the wrong function, or by using a different runtime version, which to me feels comparable to the hazards of raw multithreading.
In any case I suppose many styles of Go program will exhibit accidental determinism, but it still seems too difficult to depend on as randomness can be introduced simply by invoking the wrong function, or by using a different runtime version, which to me feels comparable to the hazards of raw multithreading.