Problems with Go channels (2016)

When I did my 20% on Go at Google, about 10 years ago, we already had a semi-formal rule that channels must not appear in exported function signatures. It turns out that using CSP in any large, complex codebase is asking for trouble, and that this is true even about projects where members of the core Go team did the CSP.

If you take enough steps back and really think about it, the only synchronization primitive that exists is a futex (and maybe atomics). Everything else is an abstraction of some kind. If you're really determined, you can build anything out of anything. That doesn't mean it's always a good idea.

Looking back, I'd say channels are far superior to condition variables as a synchronized cross-thread communication mechanism - when I use them these days, it's mostly for that. Locks (mutexes) are really performant and easy to understand and generally better for mutual exclusion. (It's in the name!)

> When I did my 20% on Go at Google, about 10 years ago, we already had a semi-formal rule that channels must not appear in exported function signatures.

That sounds reasonable. From what little Erlang/Elixir code I’ve seen, the sending and receiving of messages is also hidden as an implementation detail in modules. The public interface did not expose concurrency or synchronization to callers. You might use them under the hood to implement your functionality, but it’s of no concern to callers, and you’re free to change the implementation without impacting callers.