Go by Example: Non-Blocking Channel Operations

Basic sends and receives on channels are blocking. However, we can use `select` with a `default` clause to implement non-blocking sends, receives, and even non-blocking multi-way `select`s.
	package main
	import "fmt"
	func main() { messages := make(chan string) signals := make(chan bool)
Here’s a non-blocking receive. If a value is available on `messages` then `select` will take the `<-messages` `case` with that value. If not it will immediately take the `default` case.	select { case msg := <-messages: fmt.Println("received message", msg) default: fmt.Println("no message received") }
A non-blocking send works similarly.	msg := "hi" select { case messages <- msg: fmt.Println("sent message", msg) default: fmt.Println("no message sent") }
We can use multiple `case`s above the `default` clause to implement a multi-way non-blocking select. Here we attempt non-blocking receives on both `messages` and `signals`.	select { case msg := <-messages: fmt.Println("received message", msg) case sig := <-signals: fmt.Println("received signal", sig) default: fmt.Println("no activity") } }

$ go run non-blocking-channel-operations.go 
no message received
no message sent
no activity

Previous example: Timeouts.