Example of channels

executor.go

package main

import (
	"fmt"
	"os/exec"
	"strings"
	"sync"
)

var wg sync.WaitGroup

func execCode(code string) string {
	cmd := exec.Command(code)
	builder := strings.Builder{}
	cmd.Stdout = &builder

	err := cmd.Run()
	if err != nil {
		return err.Error()
	}
	return builder.String()

}
func worker(ch chan string, out chan string) {
	wg.Add(1)
	for cmd := range ch {
		t := execCode(cmd)
		out <- t
	}
	wg.Done()

}

func closeOutput(out chan string) {
	wg.Wait()
	close(out)
}

func main() {
	//ch := make(chan string, 100)
	//out := make(chan string, 100)
	//
	//go worker(ch, out)
	//go worker(ch, out)
	//go worker(ch, out)
	//go printer(out)
	//
	//var s string
	//var err error
	//n := 0
	//for _, err = fmt.Scanln(&s); err == nil; _, err =  fmt.Scanln(&s) {
	//	fmt.Println("Readed", s)
	//	n += 1
	//	ch <- s
	//}
	//
	//time.Sleep(2 * time.Second)

	ch := make(chan string, 10)
	out := make(chan string, 10)

	go worker(ch, out)
	go worker(ch, out)
	go worker(ch, out)

	var err error
	var s string
	for _, err = fmt.Scanln(&s); err == nil; _, err =  fmt.Scanln(&s) {
		ch <- s
	}
	close(ch)
	go closeOutput(out)
	for output := range out {
		fmt.Println(output)
	}


}