golang 深坑 concurrent map writes

golang map

真的是深坑，PHP中直接写入没问题，GOLANG和PHP不一样，必须加锁。

package main

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

var m = make(map[int]int)
var m2 = make(map[int]int)
var m3 = make(map[int]int)
var lock sync.Mutex

func main() {
	for i := 0; i < 1000; i++ {
		go func(n int) {
			lock.Lock() //加锁,加锁期间其他协程会进入阻塞状态直到解锁
			time.Sleep(time.Duration(1)*time.Second)
			fmt.Println(n, "在执行")
			m[n] = n
			m2[n] = n
			m3[n] = n
			for j := 0; j < 1000; j++ {
				m[n] = j
				m2[n] = j
				m3[n] = j
			}
			lock.Unlock() //解锁
		}(i)
	}
	fmt.Println("finished.")
	//time.Sleep(time.Duration(20)*time.Second)
}

加锁。