Go教程:24 Go协程Goroutines

sum()     // 普通的求和函数同步的调用
go sum()  // Goroutine 异步执行求和函数,不需要等待它执行完毕

package main

import (
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"time"
)

func responseSize(url string) {
	fmt.Println("Step1: ", url)
	response, err := http.Get(url)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println("Step2: ", url)
	defer response.Body.Close()

	fmt.Println("Step3: ", url)
	body, err := ioutil.ReadAll(response.Body)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println("Step4: ", len(body))
}

func main() {
	go responseSize("https://mojotv.cn")
	go responseSize("https://segmentfault.com/u/mojotech/articles")
	go responseSize("https://www.zhihu.com/people/ericzhou-91/posts")
	time.Sleep(10 * time.Second)
}

package main

import (
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"sync"
)

// WaitGroup 用来等待程序执行完成全部的goroutine
var wg sync.WaitGroup

func responseSize(url string) {
	// 调用waitGroup的done函数,告知全部goroutine都执行完成
	defer wg.Done()

	fmt.Println("第一步: ", url)
	response, err := http.Get(url)
	if err != nil {
		log.Fatal(err)
	}

	fmt.Println("第二步: ", url)
	defer response.Body.Close()

	fmt.Println("第三步: ", url)
	body, err := ioutil.ReadAll(response.Body)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println("第四步: ", len(body))
}

func main() {
	// 因为有三个goroutine 添加计数3
	wg.Add(3)
	fmt.Println("开始执行Goroutines")

	go responseSize("https://mojotv.cn")
	go responseSize("https://segmentfault.com/u/mojotech/articles")
	go responseSize("https://www.zhihu.com/people/ericzhou-91/posts")

	// 等待goroutine 执行完毕
	wg.Wait()
	fmt.Println("程序执行完毕")
}

package main

import (
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"sync"
)

// WaitGroup 用来等待程序执行完成全部的goroutine
var wg sync.WaitGroup

func responseSize(url string, nums chan int) {
	// 调用waitGroup的done函数,告知全部goroutine都执行完成
	defer wg.Done()

	response, err := http.Get(url)
	if err != nil {
		log.Fatal(err)
	}
	defer response.Body.Close()
	body, err := ioutil.ReadAll(response.Body)
	if err != nil {
		log.Fatal(err)
	}
	// 传递值到无缓存channel
	nums <- len(body)
}

func main() {
	nums := make(chan int) // 声明无缓存的channel
	wg.Add(1)
	go responseSize("https://mojotv.cn", nums)
	fmt.Println(<-nums) // Read the value from unbuffered channel
	wg.Wait()
	close(nums) // Closes the channel
}

package main

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

var i int

func work() {
	time.Sleep(250 * time.Millisecond)
	i++
	fmt.Println(i)
}

func routine(command <-chan string, wg *sync.WaitGroup) {
	defer wg.Done()
	var status = "开始"
	for {
		select {
		case cmd := <-command:
			fmt.Println(cmd)
			switch cmd {
			case "Stop":
				return
			case "Pause":
				status = "暂停"
			default:
				status = "开始"
			}
		default:
			if status == "开始" {
				work()
			}
		}
	}
}

func main() {
	var wg sync.WaitGroup
	wg.Add(1)
	command := make(chan string)
	go routine(command, &wg)

	time.Sleep(1 * time.Second)
	command <- "暂停"

	time.Sleep(1 * time.Second)
	command <- "开始"

	time.Sleep(1 * time.Second)
	command <- "停止"

	wg.Wait()
}

package main

import (
	"fmt"
	"runtime"
	"sync"
	"sync/atomic"
)

var (
	counter int32          // 计数器可以被所有的goroutine ++
	wg      sync.WaitGroup // wg 等待全部goroutine 都执行完毕
)

func main() {
	wg.Add(3) // 设置计数3 为下面三个goroutines

	go increment("Python")
	go increment("Java")
	go increment("Golang")

	wg.Wait() // Wait for the goroutines to finish.
	fmt.Println("计数:", counter)

}

func increment(name string) {
	defer wg.Done() // 任务调度告诉main goroutine 这个goroutine 执行完毕

	for range name {
		atomic.AddInt32(&counter, 1)
		runtime.Gosched() // Gosched生成处理器,允许其他goroutine运行.它不会挂起当前的goroutine,因此执行将自动恢复
	}
}

package main

import (
	"fmt"
	"sync"
)

var (
	counter int32          // 技术器可以被全部goroutine操作.
	wg      sync.WaitGroup // wg 等待全部goroutine 都执行完毕
	mutex   sync.Mutex     // mutex 定义代码关键section
)

func main() {
	wg.Add(3) //

	go increment("mojotv.cn")
	go increment("Eric Zhou")
	go increment("Golang")

	wg.Wait() // Wait for the goroutines to finish.
	fmt.Println("Counter:", counter)

}

func increment(lang string) {
	defer wg.Done() // 调度器告诉main goroutine 此goroutine执行完毕

	for i := 0; i < 3; i++ {
		mutex.Lock()
		{
			fmt.Println(lang)
			counter++
		}
		mutex.Unlock()
	}
}