Processing all files with same extension in master-worker concurrency way

Master-worker.go

package main

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"sync"
)

var (
	// use this to control all worker to wait
	wg = &sync.WaitGroup{}
)

// do task
func do(goroutine int, zipPath string) {
	// waitgroup -1 after finishing this task
	defer wg.Done()
	// Here I replace zip with csv
	zipPath = strings.Replace(zipPath, "zip", "csv", -1)
	fmt.Printf("goroutine %d done zip %s\n", goroutine, zipPath)
}

// assign work to worker
func worker(works <-chan string, goroutine int) {
	for work := range works {
		do(goroutine, work)
	}
}

func startWorkerPool(works <-chan string, size int) {
	for i := 0; i < size; i++ {
		go worker(works, i)
	}
}

func findFiles(folderPath string, works chan string, idx int) int {
	err := filepath.Walk(folderPath,
		func(path string, info os.FileInfo, err error) error {
			if err != nil {
				return err
			} else if path[len(path)-3:] == "zip" {
				// find one file, waitgroup+1
				wg.Add(1)
				works <- path
				idx++
			}
			return nil
		})
	if err != nil {
		fmt.Println(err)
	}
	return idx
}

func main() {
	works := make(chan string)

	// assign workers
	startWorkerPool(works, 2)

	folderPath := "/Users/kevin/Desktop/temp"
	idx := 0
	idx = findFiles(folderPath, works, idx)

	// wait untill each worker finishes their task
	wg.Wait()
	fmt.Println("\nTotal files:", idx)

}