worker_pool.go

package main

import (
	"fmt"
	"log"
	"net/http"
	"runtime"
	"time"
)

type jobInput struct {
	/* ... */
}
type jobOutput struct {
	/* ... */
}

func process(j jobInput) jobOutput {
	time.Sleep(2 * time.Second)
	log.Println("CONVERT")
	return jobOutput{} //
}

type Job struct {
	in  jobInput
	out chan<- jobOutput
}

var jobs = make(chan Job, 100)

func worker() {
	for {
		elt := <-jobs
		elt.out <- process(elt.in)
	}
}

func handler(w http.ResponseWriter, r *http.Request) {
	var j jobInput
	o := make(chan jobOutput)

	jobs <- Job{j, o}
	jobOutput := <-o
	_ = jobOutput
	fmt.Fprintf(w, "Hello, you've requested: %s\n", r.URL.Path)
}

func main() {

	concurrentJobs := runtime.NumCPU() - 1

	for i := 0; i < concurrentJobs; i++ {
		go worker()
		fmt.Printf("Start worker n %d\n", i+1)
	}

	http.HandleFunc("/convert", handler)

	http.ListenAndServe(":8080", nil)
}