Ch04_Thread

Yang Haoran 12/22/2022 Go

# 协程

关键字：go

func main() {
	go test()
	for i := 0; i < 10; i++ {
		fmt.Println("from main", i)
		time.Sleep(time.Millisecond)
	}

}

func test() {
	for i := 0; i < 10; i++ {
		fmt.Println("from go: ", i)
		time.Sleep(time.Millisecond)
	}

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result：

from go:  0
from main 0
from main 1
from go:  1
from go:  2
from main 2
from main 3
from go:  3
from go:  4
from main 4
from main 5
from go:  5
from main 6
from go:  6
from go:  7
from main 7
from main 8
from go:  8
from go:  9
from main 9

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# MPG 模式

自动挂载到非阻塞的线程执行

# Channel

协程之间公用同一个变量的时侯会出现问题

func multi(i int) {
	var result int
	for j := 1; j < i+1; j++ {
		result *= i
	}
	m[i] = result
}
var m = make(map[int]int)

func main() {
	for i := 0; i < 200; i++ {
		go multi(i)
	}
	time.Sleep(time.Second * 10)

	for k, v := range m {
		fmt.Println("output: ", k, "-->", v)
	}

}

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解决办法1：加互斥锁

解决办法2： channel(线程安全)

读写数据：

func main() {
	//容量为3
	var strCha = make(chan string, 3)
	strCha <- "aaa"
	strCha <- "bbb"
	//strCha <- "ccc"
	fmt.Println(len(strCha)) //2
	fmt.Println(cap(strCha)) //3
	str := <-strCha
	fmt.Println(str)         // aaa
	fmt.Println(len(strCha)) //1
	fmt.Println(cap(strCha)) //3
	//关闭channel，不能往里面写数据了，但是还是可以往里面读数据
	close(strCha)

}