在无限循环中杀死方法（golang）

Question

I am working with a piece of code that has an intentional infinite loop, I can't modify that code. I want to write some tests on that method (e.g. make sure it triggers actions at the right times) but I don't want to orphan a bunch of go routines. So I am trying to find a way that I can kill/interrupt that goroutine.

I was thinking of trying to wrap it in a wrapper function that would kill it after a signal. Like this (doesn't work).

func wrap(inf func()) func() {
  return func() {
    select {
    case inf():
    case <-time.After(5 * time.Second):
    }
  }
}

func main() {
  go wrap(inf())()
  // do things
}

All the variations I can think of don't really work. I was thinking of wrapping the inf in a function that writes to a channel (that will never get called), or something with a return statement. And then the select can read from that. The problem is then you have to launch that. If you do it in this routine you're never getting to the select. If you do it in another routine, you've just made the problem worse.

So, is there a way that I can kill that routine?

(yes - I would rather change the infinite loop code, but can't here)

Answer 1

If you can't change the loop code, you can't kill the loop. Go is rather intentionally designed such that there's no way to kill a goroutine from outside of the goroutine, short of actually terminating the program itself.

If you can change the loop itself, the typical method of killing a routine is to provide a quit channel to the goroutine, and then close (or send on) that channel to tell the loop to exit. Example:

quitCh := make(chan struct{})
go func() {
    for {
        select {
        case <-quitCh:
            return
        // other cases to handle what you need to do
        }
    }
}()

// Once you're done
close(quitCh) // goroutine exits

But without some way to coding that closure behavior into the loop itself, there's no way (to my knowledge) of specifically killing that goroutine or terminating the loop within it (unless you can trigger a panic in it, but that's a terrible way to handle that issue)