golang读写锁RWMutex

读写锁是针对读写的互斥锁

基本遵循两大原则:

1、可以随便读,多个goroutine同时读

2、写的时候,啥也不能干。不能读也不能写

RWMutex提供了四个方法:

func (*RWMutex) Lock // 写锁定

func (*RWMutex) Unlock // 写解锁

func (*RWMutex) RLock // 读锁定

func (*RWMutex) RUnlock // 读解锁

一、随便读

package main
import (
 "sync"
 "time"
)
var m *sync.RWMutex
func main() {
 m = new(sync.RWMutex)
 
 // 多个同时读
 go read(1)
 go read(2)
 time.Sleep(2*time.Second)
}
func read(i int) {
 println(i,"read start")
 m.RLock()
 println(i,"reading")
 time.Sleep(1*time.Second)
 m.RUnlock() 
 println(i,"read over")
}

1 read start

1 reading

2 read start

2 reading

1 read over

2 read over

可以看出1 读还没有结束,2已经在读

二、写的时候啥也不能干

package main
import (
 "sync"
 "time"
)
var m *sync.RWMutex
func main() {
 m = new(sync.RWMutex)
 
 // 写的时候啥也不能干
 go write(1)
 go read(2)
 go write(3)
 time.Sleep(2*time.Second)
}
func read(i int) {
 println(i,"read start")
 m.RLock()
 println(i,"reading")
 time.Sleep(1*time.Second)
 m.RUnlock() 
 println(i,"read over")
}
func write(i int) {
 println(i,"write start")
 m.Lock()
 println(i,"writing")
 time.Sleep(1*time.Second)
 m.Unlock()
 println(i,"write over")
}

1 write start

1 writing

2 read start

3 write start

1 writing over

2 reading

2 read over

3 writing

3 write over

本文来自:每日go语言

感谢作者:白玉雄

查看原文:golang读写锁RWMutex

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