Go Program in response to : https://medium.com/@qianfg/why-do-we-need-this-2-tier-channel-thing-instead-of-just-have-multiple-worker-goroutines-read-from-d29559042a33

handler.go

package main

import (
	"fmt"
	"net/http"
)

func handler(w http.ResponseWriter, r *http.Request) {
	query := r.URL.Query()
	name := query.Get("name")
	fmt.Println("Query", name)

	// Pass it to the worker
	jobQueue <- name

	// Send response
	fmt.Fprintf(w, "Hello %s", name)
}

main.go

package main

import "net/http"

var jobQueue chan string

func main() {
	jobQueue = make(chan string)

	worker := Worker{maxWorkers: 2}
	worker.start()

	http.HandleFunc("/", handler)
	http.ListenAndServe(":8000", nil)
}

workers.go

package main

import (
	"fmt"
	"time"
)

func doWork(val string) string {
	fmt.Println("Worker", val)
	time.Sleep(10 * time.Second)
	return val
}

// Worker listens to the jobQueue Channel
type Worker struct {
	maxWorkers int
}

func (w Worker) start() {
	for i := 0; i < w.maxWorkers; i++ {
		go func() {
			fmt.Println("Coroutine Running ...")
			for x := range jobQueue {
				x := doWork(x)
				fmt.Println("Result", x)
			}
		}()
	}
}