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Mastering Concurrency in Go

Quit Channel

Explore how to implement the quit channel pattern in Go for managing concurrency in goroutines and channels. Understand how to signal completion, break loops, and use WaitGroups to coordinate communication and termination in concurrent programs.

We'll cover the following...

You will notice that you have probably seen the quit channel pattern in the coding examples before. Let’s discover more about it!

So we’ll set up a car race competition. In the code below, we launch three goroutines by calling the Race function in a for-loop. Now we are only interested in the race until one of the cars reaches the finishing line. Let’s see how it’s done:

Go (1.6.2)
package main
import ( "fmt"
         "math/rand" 
         "time")
func Race(channel, quit chan string, i int) {
  
  channel <- fmt.Sprintf("Car %d started!", i)  
    for{
      rand.Seed(time.Now().UnixNano())
      time.Sleep(time.Duration(rand.Intn(500)+500) * time.Millisecond)
      quit <- fmt.Sprintf("Car %d reached the finishing line!", i)
    }
}
func main() {
  
  channel := make(chan string)
  quit := make(chan string)
  
  for i:=0; i < 3; i++{
    go Race(channel,quit,i)
  }
  for{
    select{
      case raceUpdates := <-channel:
        fmt.Println(raceUpdates)
      case winnerAnnoucement := <-quit:
        fmt.Println(winnerAnnoucement)  
       return
      
    }
  }
}

After the goroutines start concurrently, we have a select statement from line 27 to line 34.

for{
    select{
      case raceUpdates := <-channel:
        fmt.Println(raceUpdates)
      case winnerAnnoucement := <-quit:
        fmt.Println(winnerAnnoucement)  
       return
...