Golang channel sample code.

go-routine-select-nil-pattern.go

package main

import (
	"fmt"
)

func main() {

	ch1 := make(chan int)
	ch2 := make(chan int)

	go func() {
		ch1 <- 1
		close(ch1)
		fmt.Println("closed ch1")
	}()

	go func() {
		fmt.Println("set ch2")
		ch2 <- 2
		close(ch2)
		fmt.Println("closed ch2")
	}()

	for {
		select {
		case v, ok := <-ch1:
			fmt.Printf("ch1 %d %v\n", v, ok)
			if !ok {
				ch1 = nil
			}
		case v, ok := <-ch2:
			fmt.Printf("ch2 %d\n", v)
			if !ok {
				ch2 = nil
			}
		default:
			fmt.Println("wait")
		}

		if ch1 == nil && ch2 == nil {
			fmt.Println("all channel closed")
			break
		}
	}

	fmt.Println("done")
}