Simple pool of goroutine workers with input/output channels

worker-pool.go

// Worker pool example with input and output channel and multiple workers
// solves the deadlock caused by the r chanel not read on time, so blocking all
// worker on ri <- v

package main

import (
	"fmt"
	"time"
	"sync"
)

func main () {
	c := make(chan int)
	r := make(chan int)
	var w sync.WaitGroup

	for i := 1; i <= 5; i++ {
		w.Add(1)
		go func(i int, ci <-chan int, ri chan int) {
			defer w.Done()
			j := 1
			for v := range ci {
				time.Sleep(time.Millisecond)
				j += 1
				ri <- v
			}
		}(i, c, r)
	}

        // This SOLVES the deadlock, the input channel is
        // populated from own goroutine
        w.Add(1)
	go func(ci <-chan int) {
	        defer w.Done()
		for i := 1; i <= 25; i++ {
			c <- i
		}
	}(c)

	for i := 1; i <= 25; i++ {
		msg := <-r
		fmt.Printf("msg=%d\n", msg)
	}

	close(c)
	w.Wait()
	close(r)
}