Go之组件学习-channel(concurrency篇)

文章目录

导语:

最近在学习关于go语言的concurrency的channel模块,就看到了ardan labs里面的一些例子,促进理解channel一些原理和使用

一、channel的定义

Channels allow goroutines to communicate with each other through the use of signaling semantics. Channels accomplish this signaling through the use of sending/receiving data or by identifying state changes on individual channels. Don't architect software with the idea of channels being a queue, focus on signaling and the semantics that simplify the orchestration required.

通道允许goroutine通过使用信令语义相互通信。信道通过使用发送/接收数据或识别单个信道上的状态变化来完成该信令。不要以通道是队列的想法来构建软件,而应关注简化所需编排的信令和语义。

二、channel的使用方式

在go中定义一个chan,即可开启通道模式

例如

	ch := make(chan int, 1)
	ch <- 1
	fmt.Println(<-ch)

以上的 ch<-1 就是将数据发送到channel中,而==<-ch==就是将数据发送出去。

这样可以实现channel管道接收和发送数据。

三、channel的一些场景

buffered(阻塞)

Go之组件学习-channel(concurrency篇)

阻塞场景,并发场景,多数据的发送和多用户接收需要从channel中慢慢存和取,时间上延时性高,但是实现了高性能高效率传输。

unbuffered(非阻塞)

Go之组件学习-channel(concurrency篇)

非阻塞场景也是比较常见的,它实现了数据的快速发送和接收,常用于对等单个gorountine使用,一对一聊天室?低延时,但需要多个gorountine的建立,消耗大量性能。

四、channel的一些简单场景应用

1)父goroutine通过channel管道等待子goroutine的数据发送

// waitForResult: In this pattern, the parent goroutine waits for the child
// goroutine to finish some work to signal the result.
// 父goroutine等待信号结果
func waitForResult() {
	ch := make(chan string)

	go func() {
		time.Sleep(time.Duration(rand.Intn(500)) * time.Millisecond)
		ch <- "data"
		fmt.Println("child : sent signal")
	}()

	d := <-ch
	fmt.Println("parent : recv'd signal :", d)

	time.Sleep(time.Second)
	fmt.Println("-------------------------------------------------")
}

2)父goroutine发出100份信号,子goroutine一个pool池将等待信号接收

// pooling: In this pattern, the parent goroutine signals 100 pieces of work
// to a pool of child goroutines waiting for work to perform.
//父goroutine发出100份信号,子goroutine池将等待并工作
func pooling() {
	ch := make(chan string)
	//设置可以执行的最大CPU数量,指的是线程
	g := runtime.GOMAXPROCS(0)
	fmt.Println("====",g)
	for c := 0; c < g; c++ {
		go func(child int) {
			fmt.Println("!!!!!1")
			for d := range ch {
				fmt.Printf("child %d : recv'd signal : %s\n", child, d)
			}
			fmt.Printf("child %d : recv'd shutdown signal\n", child)
		}(c)
	}

	const work = 100
	for w := 0; w < work; w++ {
		ch <- "data" + strconv.Itoa(w)
		fmt.Println("parent : sent signal :", w)
	}

	close(ch)
	fmt.Println("parent : sent shutdown signal")

	time.Sleep(time.Second)
	fmt.Println("-------------------------------------------------")
}

3)使用channel管道模拟两个人网球比赛

// Sample program to show how to use an unbuffered channel to
// simulate a game of tennis between two goroutines.
//两个goroutines之间模拟网球比赛。
package main

import (
	"fmt"
	"math/rand"
	"sync"
	"time"
)

func init() {
	rand.Seed(time.Now().UnixNano())
}

func main() {

	// Create an unbuffered channel.
	court := make(chan int)

	// wg is used to manage concurrency.
	var wg sync.WaitGroup
	wg.Add(2)

	// Launch two players.
	go func() {
		player("Serena", court)
		wg.Done()
	}()

	go func() {
		player("Venus", court)
		wg.Done()
	}()

	// Start the set.
	court <- 1

	// Wait for the game to finish.
	wg.Wait()
}

// player simulates a person playing the game of tennis.
func player(name string, court chan int) {
	for {

		// Wait for the ball to be hit back to us.
		ball, wd := <-court
		if !wd {

			// If the channel was closed we won.
			fmt.Printf("Player %s Won\n", name)
			return
		}

		// Pick a random number and see if we miss the ball.
		n := rand.Intn(100)
		if n%13 == 0 {
			fmt.Printf("Player %s Missed\n", name)

			// Close the channel to signal we lost.
			close(court)
			return
		}

		// Display and then increment the hit count by one.
		fmt.Printf("Player %s Hit %d\n", name, ball)
		ball++

		// Hit the ball back to the opposing player.
		court <- ball
	}
}


五、channel 一些禁止项

Go之组件学习-channel(concurrency篇)

在数据发送和接收这两种方式里,在channel管道关闭后,也有一些禁止项

比如说

管道closed后,不允许在发送数据,如果在发送数据会产生panic报错。

	ch := make(chan int,2)
	ch <- 1 //发送1到管道ch
	fmt.Println(<-ch)//接收管道的数据1
	close(ch)//关闭管道
	ch <- 2 //发送管道报错,已经关闭管道顾不可再发送,panic
	fmt.Println(<-ch)

以上代码将会报panic: send on closed channel错误

经过测试,改成以下代码印证了这个禁止项

	ch := make(chan int,2)
	ch <- 1//发送1到管道ch
	ch <- 2//发送2到管道ch
	fmt.Println(<-ch)//接收管道的数据1
	close(ch)
	fmt.Println(<-ch)//接收管道的数据2

文章借鉴

  • ardan labs go training - github web adress “https://github.com/ardanlabs/gotraining”
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