goroutine.go

package main

import (
	"fmt"
	"time"
)

func main() {
	const totalExecuteNum = 6
	const maxConcurrencyNum = 3
	sig := make(chan string, maxConcurrencyNum)
	res := make(chan string, totalExecuteNum)
	defer close(sig)
	defer close(res)
	fmt.Printf("start concurrency execute %s \n", time.Now())
	for i := 0; i < totalExecuteNum; i++ {
		go wait6sec(sig, res, fmt.Sprintf("no%d", i))
	}

	for {
		if len(res) >= totalExecuteNum {
			break
		}
	}

	fmt.Printf("end concurrency execute %s \n", time.Now())

}

func wait6sec(sig chan string, res chan string, name string) {
	sig <- fmt.Sprintf("sig %s", name)
	time.Sleep(6 * time.Second)
	fmt.Printf("%s:end wait 6sec \n", name)
	res <- fmt.Sprintf("sig %s", name)
	<-sig
}