Channel Synchronization

We can use channels to synchronize execution across goroutines. Here’s an example of using a blocking receive to wait for a goroutine to finish. When waiting for multiple goroutines to finish, you may prefer to use a WaitGroup.

package main

import (
    "fmt"
    "time"
)

// This is the function we’ll run in a goroutine.
// The done channel will be used to notify
// another goroutine that this function’s work is done.
func worker(done chan bool) {
    fmt.Print("working...")
    time.Sleep(time.Second)
    fmt.Println("done")

    // Send a value to notify that we’re done.
    done <- true
}

func main() {

    // Start a worker goroutine, giving it the channel to notify on.
    done := make(chan bool, 1)
    go worker(done)

    // Block until we receive a notification from the worker on the channel.
    <-done
}

$ go run channel-synchronization.go
working...done

If you removed the <- done line from this program, the program would exit before the worker even started.