golang concurrent sum

sum.go

package main

import (
	"fmt"
	"sync"
)

func main() {
	process()
}

func process() {
	jobs := make(chan string, 5)
	results := make(chan string, 5)

	//
	// create jobs
	//
	wg := new(sync.WaitGroup)

	for w := 1; w <= 3; w++ {
		wg.Add(1)
		go mapping(jobs, results, wg)
	}

	feed(jobs)

	go func() {
		wg.Wait()
		close(results)
	}()

	sum := reduce(results)
	fmt.Println(sum)
}

func feed(jobs chan<- string) {
	records := []string{"foo", "bar", "exp", "foo", "exp", "fish", "dog", "cat", "tiger"}
	for i := 0; i < len(records); i++ {
		jobs <- records[i]
	}
	close(jobs)
}

func mapping(jobs <-chan string, results chan<- string, wg *sync.WaitGroup) {
	defer wg.Done()
	for j := range jobs {
		results <- j
	}
}

func reduce(results <-chan string) map[string]int {
	sum := map[string]int{}
	for v := range results {
		sum[v] += 1
	}
	return sum
}