Question

I made a simple clock signal using goroutines:

func clockloop(ch chan byte) {
    count := 0
    for {
        time.Sleep(FRAMELEN)
        count++
    innerfor:
        for count {
            select {
                case ch <- 1:
                    count--
                default:
                    break innerfor
            }
        }
    }
}

func MakeClock() chan byte {
    clock := make(chan byte)
    go clockloop(clock)
    return clock
}

I know this clock is imprecise but that is irrelevant. What I want to know is what is the best way to stop this goroutine?

Ideally, I would have liked it to stop as soon as any listeners to the channel go out of scope but I do know how to do that (much like a garbage collector but for goroutines). I have come up with two ways to stop it manually: (1) with a global stop variable that all such goroutines would check every loop and (2) with a stop channel. The disadvantage of each of these is I have to manually stop the goroutines.

Answer 1

A stop channel is a good way to do it. A goroutine must stop itself. There is no way to externally kill one.

For reference there is this thread on Go-Nuts where Ian says essentially this and Russ adds, “Killing individual goroutines is a very unstable thing to do:
it’s impossible to know what locks or other resources those
goroutines had that still needed to be cleaned up for the
program to continue running smoothly.”