Fun with `goroutines`

Saurabh Sharma

Channels are way of communication between multiple goroutines

You can declare a channel and the type of content the channel will receive like below.

var myChannel chan int

The int above is the type of data it can receive and the data can be send using

// Send 10 through channel
myChannel <- 10
//Receive the channel content
val := <- myChannel

In this blog I will just play out some sample scenarios of sending valid information and waiting for the goroutine to sed/receive the data.

Send

func send will send data [1..10] to ch and sleep ever time it is send

func send(ch chan int) {
	for i := 0; i < 10; i++ {
		time.Sleep(1 * time.Second)
		ch <- i
	}
	fmt.Println(" Sender done...")
	return
}

Receive

func receive will receive all the information sent to the channel till the last info.

func receive(ch chan int) {
	var val int

	for {
		val = <-ch
		fmt.Printf(" > %d\n", val)
		if val >= 10 {
			close(ch)
			done <- true
		}
	}
}

Term

func term() {
	done <- true
}

Main

Playing out the entry point to call the send and receive

func main() {
	fmt.Println(" --- Main ---")
	ch := make(chan int)

	go send(ch)
	go receive(ch)

	// wait on done
	<-done
	fmt.Println(" Done.. ")
}

Output

 > 0
 > 1
 > 2
 > 3
 > 4
 > 5
 > 6
 > 7
 > 8
 Sender done...
 Closing reciever...
 > 9
 Receiver done...
 Done.. 

Source repository is available here.

What If?

If you try sending a different type to the channel type defined – what shall happen?

  • Will it throw runtime error?
  • Will it ignore?
  • Will it throw compile time error?

Easier to try

var done chan bool = make(chan bool)
done <- 'a'

It just does throws compile time error

# command-line-arguments
src/main.go:57:7: cannot use 'a' (type untyped rune) as type bool in send

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