How to Signal a Go Routine to Halt without Blocking?

Signaling a Go Routine to Halt

In this scenario, a go routine needs to be instructed to cease operation. The primary challenge lies in achieving this signaling without introducing blocking behavior.

The proposed solution involves employing a secondary channel. However, conventional channel usage would lead to blocking if the go routine attempts to receive a signal from this channel while actively processing data.

Using a Select Case

To avoid blocking, the code can leverage a select case with a default clause. This allows the go routine to continue processing data until a signal is received from the secondary channel:

<code class="go">go func() {
    for {
        fmt.Println("working")
        time.Sleep(1 * time.Second)
        select {
        case <-tooLate:
            fmt.Println("stopped")
            return
        case proCh <- "processed": //this why it won't block the goroutine if the timer expirerd.
        default: // adding default will make it not block
        }
        fmt.Println("done here")
    }
}()</code>

By utilizing the default clause, the go routine can avoid blocking even when the timer expires.

Using a sync.Cond

Another approach involves utilizing a sync.Cond instead of a channel. A condition variable provides a way to wait and signal across goroutines.

Conclusion

With either a secondary channel with a default clause or a sync.Cond, you can effectively signal a go routine to stop running without resorting to blocking behavior.

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