Another option could be instead of creating a mutex, never close recv and instead have a recvClose channel. Whenever a select is used on recv, check for the recvClose channel instead of checking if recv is closed. I know it looks a little uglier, but it is less likely to deadlock. Using a lock here has the risk of getting in a recv/close deadlock (consumer of recv channel is trying to close).

Got it. I'll close this PR then.