go语言坑之并发访问map

fatal error: concurrent map read and map write

并发访问map是不安全的，会出现未定义行为，导致程序退出。所以如果希望在多协程中并发访问map，必须提供某种同步机制，一般情况下通过读写锁sync.RWMutex实现对map的并发访问控制，将map和sync.RWMutex封装一下，可以实现对map的安全并发访问，示例代码如下：

 

package main

import "sync"

type SafeMap struct {
    sync.RWMutex
    Map map[int]int
}

func main() {
    safeMap := newSafeMap(10)

    for i := 0; i < 100000; i++ {
        go safeMap.writeMap(i, i)
        go safeMap.readMap(i)
    }

}

func newSafeMap(size int) *SafeMap {
    sm := new(SafeMap)
    sm.Map = make(map[int]int)
    return sm

}

func (sm *SafeMap) readMap(key int) int {
    sm.RLock()
    value := sm.Map[key]
    sm.RUnlock()
    return value
}

func (sm *SafeMap) writeMap(key int, value int) {
    sm.Lock()
    sm.Map[key] = value
    sm.Unlock()
}