How to kill a goroutine

One goroutine can't forcibly stop another.

To make a goroutine stoppable, let it listen for a stop signal on a dedicated quit channel, and check this channel at suitable points in your goroutine.

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

Here is a more complete example, where we 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, send a number on this 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)
    number <- 0           // stops underlying goroutine
    fmt.Println(<-number) // error, no one is sending anymore
    // …
}

1
2
fatal error: all goroutines are asleep - deadlock!

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