Consider the ping pong example from http://www.golang-book.com/10/index.htm#section2.
package main
import (
"fmt"
"time"
)
func pinger(c chan string) {
for i := 0; ; i++ {
c <- "ping"
}
}
func ponger(c chan string) {
for i := 0; ; i++ {
c <- "pong"
}
}
func printer(c chan string) {
for {
msg := <- c
fmt.Println(msg)
time.Sleep(time.Second * 1)
}
}
func main() {
var c chan string = make(chan string)
go pinger(c)
go ponger(c)
go printer(c)
var input string
fmt.Scanln(&input)
}
The authors write:
"The program will now take turns printing ping and pong."
However, for this to be true, Go must decide on an order in which senders can send into a channel? Otherwise, there would be no guarantee that a ping would be sent before a pong (i.e. you can't get two pings, or two pongs in a row). How does this work?