Golang mini channel example

One of Go’s mottos is:

Share memory by communicating, don’t communicate by sharing memory

Here is a mini channel example

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package main

import "fmt"

func sendMessage(messages chan<- string) {
	messages <- "ping"
}

func main() {
	messages := make(chan string)
	go sendMessage(messages)
	msg := <-messages
	fmt.Println(msg)
}

What’s happening here is:

• We make a channel,
• We send a message to the channel by calling a function as a goroutine. (If we call a function with go in front, the code will run as a goroutine.)
• We then receive the message from the channel, assign it to a variable, and finally print the message.
• When we run this, we get ping.

By default a channel is unbuffered, meaning it is synchronized. This means that a value must be received from the channel at the same time as it’s being sent. We can verify this by calling sendMessage() directly instead of as a goroutine. If we do that, the program crashes!

Channels with buffering

It’s also possible to buffer a channel with multiple values. We do this by adding a number to the make call when we create a channel.

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package main

import "fmt"

func main() {
	messages := make(chan int, 2)
	messages <- 1
	messages <- 2
	fmt.Println(<-messages)
	fmt.Println(<-messages)
}