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@ -8,21 +8,4 @@ golang的并发通过goroutine实现,goroutine是用户态的线程,由go的
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golang提供channel用来在多个goroutine之间进行通信。
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golang提供channel用来在多个goroutine之间进行通信。
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通过go 关键字来开启一个goroutine
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只需要在调用函数前加上 go 关键字 即可开启一个goroutine
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goroutine对应的函数执行结束了,goroutine就结束了
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main函数执行完毕,由main函数创建的那些goroutine就结束了
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如何等待所有的goroutine结束之后再执行主函数?
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sync.waitGroup对象中有三个方法
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var wg sync.waitGroup
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wg.add(1) //计数器加1
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wg.done()//计数器减1
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wg.wait()//等待所有的goroutine结束
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goroutine与线程
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os线程有固定的栈内存
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@ -5,18 +5,21 @@ import (
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"time"
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"time"
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)
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)
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func hello(i int) {
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func hello() {
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fmt.Println("hello world", i)
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fmt.Println("hello")
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}
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}
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// 程序启动之后会创建一个主goroutine去执行
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// 主goroutine开启,之后所有的子协程都会自行退出
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func main() {
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func main() {
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//通过匿名函数开启goroutine
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for i := 0; i < 10; i++ {
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for i := 0; i < 10; i++ {
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go func(i int) {
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go func() {
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fmt.Println("hello world", i)
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fmt.Println(i)
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}(i)
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}() //事实上这个函数中的i去找到的是上面这个循环的i,所以当goroutine启动过快有可能在一个循环中找到i
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} //开启一个单独的goroutine 去执行hello函数(任务)
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fmt.Println("main")
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}
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time.Sleep(1 * time.Second)
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fmt.Println("this is main,2")
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//main函数结束了 由main函数启动的goroutine也都结束了
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time.Sleep(time.Second)
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}
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}
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@ -1,40 +0,0 @@
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package main
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import (
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"fmt"
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"math/rand"
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"sync"
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"time"
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)
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//waitGroup
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func f() {
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//生成随机数
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rand.New(rand.NewSource(time.Now().UnixNano()))
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for i := 0; i < 5; i++ {
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r1 := rand.Int()
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r2 := rand.Intn(10)
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fmt.Println(r1, r2)
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}
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}
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func f1(i int) {
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defer wg.Done() //任务结束后计数器-1
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time.Sleep(time.Second * time.Duration(rand.Intn(3)))
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fmt.Println(i)
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}
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var wg sync.WaitGroup
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func main() {
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for i := 0; i < 10; i++ {
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wg.Add(1)
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go f1(i)
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}
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//如何知道这10个goroutine都结束了
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wg.Wait() //等待wg的计数器减为0
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}
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