Go by Example: Closing Channels

Closing a channel indicates that no more values will be sent on it. This can be useful to communicate completion to the channel’s receivers.
	package main
	import "fmt"
In this example we’ll use a `jobs` channel to communicate work to be done from the `main()` goroutine to a worker goroutine. When we have no more jobs for the worker we’ll `close` the `jobs` channel.	func main() { jobs := make(chan int, 5) done := make(chan bool)
Here’s the worker goroutine. It repeatedly receives from `jobs` with `j, more := <-jobs`. In this special 2-value form of receive, the `more` value will be `false` if `jobs` has been `close`d and all values in the channel have already been received. We use this to notify on `done` when we’ve worked all our jobs.	go func() { for { j, more := <-jobs if more { fmt.Println("received job", j) } else { fmt.Println("received all jobs") done <- true return } } }()
This sends 3 jobs to the worker over the `jobs` channel, then closes it.	for j := 1; j <= 3; j++ { jobs <- j fmt.Println("sent job", j) } close(jobs) fmt.Println("sent all jobs")
We await the worker using the synchronization approach we saw earlier.	<-done }

	$ go run closing-channels.go sent job 1 received job 1 sent job 2 received job 2 sent job 3 received job 3 sent all jobs received all jobs
The idea of closed channels leads naturally to our next example: `range` over channels.