go并发学习

package main

import (
	"fmt"
	"sync"
)

var wg sync.WaitGroup

func hello(i int) {
	defer wg.Done()
	fmt.Print(i, "hello hello\n")
}
func main() {
	for i := 0; i < 6; i++ {
		wg.Add(1) // 启动一个goroutine就登记+1
		go hello(i)
	}

	fmt.Println("this is main done\n")
	wg.Wait() //等的goroutine都结束
}

　　

package main

import (
	"fmt"
	"sync"
)

var wg sync.WaitGroup

// func do(c chan int) {
// 	ret := <-c
// 	fmt.Println("接收成功", ret)

// 	defer wg.Done()
// }
func sendint(c chan int) {
	for i := 0; i < 101; i++ {
		c <- i //网管道放int
	}
	close(c)
	defer wg.Done()
}
func sendandto(c, c1 chan int) {
	for {
		i, ok := <-c // 通道关闭后再取值ok=false
		if !ok {
			break
		}
		c1 <- i * i
	}
	close(c1)
	defer wg.Done()
}
func main() {
	// ch := make(chan int)
	// wg.Add(1) // 启动一个goroutine就登记+1
	// go do(ch)
	// ch <- 10
	// wg.Wait()
	// fmt.Println("发送成功")
	ch := make(chan int, 1)
	ch1 := make(chan int, 1)
	wg.Add(1) // 启动一个goroutine就登记+1
	go sendint(ch)
	wg.Add(1) // 启动一个goroutine就登记+1
	go sendandto(ch, ch1)
	for i := range ch1 { // 通道关闭后会退出for range循环
		fmt.Println(i)
	}

	wg.Wait()
}

　　

package main

import (
	"fmt"
	"runtime"
)

func send(str string) {
	for i := 0; i < 3; i++ {
		fmt.Printf("str:%v,%d\n", str, i)
		if i > 0 {
			runtime.Goexit()
		}

	}

}
func main() {
	go send("php")
	for i := 0; i < 3; i++ {
		runtime.Gosched()
		fmt.Printf("str:%v\n", "java")
	}
	fmt.Printf("str:%v\n", "end")
}