Go: Stop a goroutine

One goroutine can't forcibly stop another—a gorou­tine can stop only by returning from it's top level function.

To make a goroutine stoppable, let it listen for a stop signal on a channel. Here's an example:

quit := make(chan struct{})
go func() {
        for {
                select {
                case <-quit:
                        return
                default:
                        // …
                }
        }
}()

// …
close(quit)

Sometimes it's convenient to use a single channel for both data and signalling:

// Generator returns a channel that produces the numbers 1, 2, 3,…
// To stop the underlying goroutine, close the channel.
func Generator() chan int {
        ch := make(chan int)
        go func() {
                n := 1
                for {
                        select {
                        case ch <- n:
                                n++
                        case <-ch:
                                return
                        }
                }
        }()
        return ch
}

func main() {
        number := Generator()
        fmt.Println(<-number)
        fmt.Println(<-number)
        close(number)
        // …
}

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