一、读写互斥锁

package main

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

//读写互斥锁

var (
	x      = 0
	wg     sync.WaitGroup
	lock   sync.Mutex
	rwlock sync.RWMutex
)

func read() {
	defer wg.Done()
	rwlock.RLock()
	fmt.Println(x)
	time.Sleep(time.Millisecond)
	rwlock.RUnlock()
}
func write() {
	defer wg.Done()
	rwlock.Lock()
	x = x + 1
	time.Sleep(time.Millisecond * 5)
	rwlock.Unlock()
}

func main() {
	start := time.Now()
	for i := 0; i < 10; i++ {
		go write()
		wg.Add(1)
	}
	time.Sleep(time.Second)
	for i := 0; i < 1000; i++ {
		go read()
		wg.Add(1)
	}

	wg.Wait()
	fmt.Println(time.Now().Sub(start))
}

 二、互斥锁

package main

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

//互斥锁

var (
	x      = 0
	wg     sync.WaitGroup
	lock   sync.Mutex
	rwlock sync.RWMutex
)

func read() {
	defer wg.Done()
	lock.Lock()
	fmt.Println(x)
	time.Sleep(time.Millisecond)
	lock.Unlock()
}
func write() {
	defer wg.Done()
	lock.Lock()
	x = x + 1
	time.Sleep(time.Millisecond * 5)
	lock.Unlock()
}

func main() {
	start := time.Now()
	for i := 0; i < 10; i++ {
		go write()
		wg.Add(1)
	}
	time.Sleep(time.Second)
	for i := 0; i < 1000; i++ {
		go read()
		wg.Add(1)
	}
	wg.Wait()
	fmt.Println(time.Now().Sub(start))
}

 三、结论

如上述代码所示，读的操作有1000次，写的操作有10次。当读的操作要远远大于写的操作的时候，读写互斥锁的效率一定是比互斥锁效率要高的。因为这1000次读就不需要别人去等了，当获取读锁的时候其他人还是能读到；只有在获取写入锁的时候，其他人才需要等待。