Golang实例讲解，slice并发读写的线程安全性问题

/**
 * 并发编程，切片的线程安全性问题
 */
package main

import (
   "fmt"
   "sync"
   "time"
)

var list []int = []int{}
var wgList sync.WaitGroup = sync.WaitGroup{}
var muList sync.Mutex = sync.Mutex{}

func main() {
   // 并发启动的协程数量
   max := 10000
   fmt.Printf("list add num=%d\n", max)
   wgList.Add(max)
   time1 := time.Now().UnixNano()
   for i := 0; i < max; i++ {
      go addNotSafe()
   }
   wgList.Wait()
   time2 := time.Now().UnixNano()
   fmt.Printf("list len=%d, time=%d ms\n", len(list), (time2-time1)/1000000)

   // 覆盖后再执行一次
   list = []int{}
   fmt.Printf("new list add num=%d\n", max)
   wgList.Add(max)
   time3 := time.Now().UnixNano()
   for i := 0; i < max; i++ {
      go addSafe()
   }
   wgList.Wait()
   time4 := time.Now().UnixNano()
   fmt.Printf("new list len=%d, time=%d ms\n", len(list), (time4-time3)/1000000)
}

// 线程不安全的方法
func addNotSafe() {
   list = append(list, 1)
   wgList.Done()
}

// 线程安全的方法，增加了互斥锁
func addSafe() {
   muList.Lock()
   list = append(list, 1)
   muList.Unlock()
   wgList.Done()
}

list add num=10000

list len=9989, time=2 ms

new list add num=10000

new list len=10000, time=2 ms

for {

    data := <- chanList

    list = append(list, data)

}