select.go

package main

import (
	"fmt"
	"time"
)

func main() {
	c1 := make(chan string)
	c2 := make(chan string)

	go func() {
		time.Sleep(time.Second * 1)
		c1 <- "one"
	}()
	go func() {
		time.Sleep(time.Second * 2)
		c2 <- "two"
	}()

	for i := 0; i < 2; i++ {
		select {
		case msg1 := <-c1:
			fmt.Println("received", msg1)
		case msg2 := <-c2:
			fmt.Println("received", msg2)
		}
	}

// Each channel will receive a value after some amount of time, 
// to simulate e.g. blocking RPC operations executing in concurrent goroutines.
// We’ll use select to await both of these values simultaneously, 
// printing each one as it arrives.We receive the values "one" and then "two" as expected
// Note that the total execution time is only ~2 seconds since both the 1 and 2 second Sleeps execute concurrently.