GO互斥锁、读写锁

读写锁：
读时共享，写时独占。写锁优先级比读锁优先级高

package main
import (
    "fmt"
    "sync"
    "time"
)
var mutex sync.Mutex //新建一个互斥锁，默认状态为0，未加锁
func printer1(str string){
    mutex.Lock() //访问共享数据之前，加锁
    for _,ch := range str {
        fmt.Printf("%c",ch)
        time.Sleep(time.Millisecond*300)
    }
    mutex.Unlock()//访问结束，解锁
}
func person11 () {
    printer1("Hello")
}
func person22 () {
    printer1("World")
}
func main() {
    go person11()
    go person22()

    for {
        ;
    }
}

通过mutex实现读时共享，写时独占
代码示例：

package main
import (
    "fmt"
    "math/rand"
    "sync"
    "time"
)
var index int
var rwMutxt1 sync.RWMutex
func readRand1(num int)  {
    for {
        rwMutxt1.RLock()
        num =  index
        fmt.Printf("########thread%d读，读出%d\n",num,index)
        rwMutxt1.RUnlock()
    }
}
func writeRand1(num int)  {
    for {
        randNum := rand.Intn(1000)
        rwMutxt1.Lock()
        index = randNum
        fmt.Printf("thread%d写，写入%d\n",num,randNum)
        time.Sleep(time.Microsecond*300)
        rwMutxt1.Unlock()
    }
}

func main()  {
    rand.Seed(time.Now().UnixNano())
    for i :=0; i < 2; i++ {
        go writeRand1(i)

    }
    for i :=0; i < 2; i++ {
        go readRand1(i)
    }
    //<- quit
    for {
        ;
    }
}

打印结果：

thread0写，写入742
########thread742读，读出742
########thread742读，读出742
thread1写，写入316
########thread316读，读出316
########thread316读，读出316
thread0写，写入729
########thread729读，读出729
########thread729读，读出729

通过channel实现不了读时共享，写时独占
代码示例：

package main

import (
    "fmt"
    "math/rand"
    "time"
)
var quit = make(chan bool)

func readRand(in <- chan int,num int)  {
    for {
        rrand := <- in
        fmt.Printf("########thread%d读，读出%d\n",num,rrand)
    }
}
func writeRand(out chan <- int,num int)  {
    for {
        randNum := rand.Intn(1000)
        out <- randNum
        fmt.Printf("thread%d写，写入%d\n",num,randNum)
        time.Sleep(time.Microsecond*300)
    }    
}

func main()  {
    ch := make(chan int)
    rand.Seed(time.Now().UnixNano())
    for i :=0; i < 5; i++ {
        go writeRand(ch,i)
    }
    for i :=0; i < 5; i++ {
        go readRand(ch,i)
    }
    //<- quit
    for {
        ;
    }
}    

打印结果：

thread3写，写入93
########thread4读，读出93
thread1写，写入604
thread2写，写入78
########thread3读，读出165
thread4写，写入165
########thread1读，读出604
########thread0读，读出78
thread0写，写入769
########thread2读，读出769