Golang等待一组协程结束

1. 利用waitgroup 

import (
	"log"
	"sync"
	"sync/atomic"
	"time"
)
func main() {
	wg := sync.WaitGroup{}
	for i := 0; i < 10; i++ {
		wg.Add(1)
		go func(i int) {
			log.Println(i)
			wg.Done()
		}(i)
	}
	wg.Wait()
}

2. 利用缓冲channel

import (
	"log"
	"time"
)

func main() {
	ch := make(chan struct{}, 10)
	var i int
	for i = 0; i < 10; i++ {
		go func(i int) {
			log.Println(i)
			ch <- struct{}{}
		}(i)
	}

	for j := i; j > 0; j-- {
		<-ch
	}
}

3. 利用非缓冲channel

package main

import (
   "log"
   "time"
)

func main() {
   ch := make(chan struct{})
   for i := 0; i < 10; i++ {
      go func(i int) {
         log.Println(i)
         ch <- struct{}{}
      }(i)
      <-ch
   }
}

4. 利用原子计数器

package main

import (
   "log"
   "time"
   "sync"
   "sync/atomic"
)

func main() {
   var total int32
   for  i := 0; i < 10; i++ {
      go func(i int) {
         log.Println(i)
         atomic.AddInt32(&total,1)
      }(i)
   }
   for atomic.LoadInt32(&total) < 10 {
      time.Sleep(time.Microsecond)
   }
}