ta_shuo

Go by Example - Mutexes

翻译自 https://gobyexample.com/

Go by Example

Go is an open source programming language designed for building simple, fast, and reliable software.

Go by Example is a hands-on introduction to Go using annotated example programs. Check out the first example or browse the full list below.

Go by Example: Mutexes

在前面的示例中我们看到如何通过原子操作来管理简单的计数器。对于更复杂的状态,我们可以使用互斥锁在多个goroutine中安全地访问数据。

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package main
import (
"fmt"
"math/rand"
"sync"
"sync/atomic"
"time"
)
func main() {
// 此处状态是一个map
var state = make(map[int]int)
// 初始化锁
var mutex = &sync.Mutex{}
// 定义两个变量用于追踪读和写的总次数
var readOps uint64 = 0
var writeOps uint64 = 0
// 启动100个goroutines读取状态值,每个goroutine耗时1毫秒
for r := 0; r < 100; r++ {
go func() {
total := 0
for {
// 随机读取状态的某一个值
// 1、加锁
// 2、读取
// 3、解锁
key := rand.Intn(5)
mutex.Lock()
total += state[key]
mutex.Unlock()
// 次数自增1
atomic.AddUint64(&readOps, 1)
// 两次读取之间睡眠1毫秒
time.Sleep(time.Millisecond)
}
}()
}
// 同上,启动10个goroutines模拟写操作
// 随机给状态赋值,写操作次数自增1,睡眠1毫秒
for w := 0; w < 10; w++ {
go func() {
for {
key := rand.Intn(5)
val := rand.Intn(100)
mutex.Lock()
state[key] = val
mutex.Unlock()
atomic.AddUint64(&writeOps, 1)
time.Sleep(time.Millisecond)
}
}()
}
// 睡眠一秒等待读写操作
// 打印出读写次数
time.Sleep(time.Second)
readOpsFinal := atomic.LoadUint64(&readOps)
fmt.Println("readOps:", readOpsFinal)
writeOpsFinal := atomic.LoadUint64(&writeOps)
fmt.Println("writeOps:", writeOpsFinal)
// 使用锁取出最后的状态值
mutex.Lock()
fmt.Println("state:", state)
mutex.Unlock()
}
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tashuo:golang ta_shuo$ go run mutex.go
readOps: 78300
writeOps: 7830
state: map[1:86 0:61 4:17 2:26 3:26]

执行程序,根据输出得知读写次数分别为78300和7830,最后的状态为map[1:86 0:61 4:17 2:26 3:26]

原文链接:Go by Example: Mutexes