go并发打印数字

​

书接上文：go并发打印数字

type5:

func main() {
	// 猜猜会打印什么，为啥？
	// runtime.GOMAXPROCS(1)
	wg := &sync.WaitGroup{}
	wg.Add(10)
	for i := 0; i < 10; i++ {
		go func() {
			defer wg.Done()
			// 1.18以后闭包的循环变量不在共享同一个地址，已解决这个bug
			print(i)
		}()
	}
	wg.Wait()
}

type6:

type worker struct {
	ch   chan int
	done func()
}

func generator(done func()) worker {
	w := worker{
		ch:   make(chan int),
		done: done,
	}
	go func() {
		for n := range w.ch {
			print(n)
			done()
		}
	}()
	return w
}

func main() {
    // 用waitGroup实现并发控制
	var (
		n  = 10
		wg sync.WaitGroup
		ws = make([]worker, n)
	)

	for i := 0; i < n; i++ {
		ws[i] = generator(func() {
			wg.Done()
		})
	}
	wg.Add(n)
	for i := 0; i < 10; i++ {
		ws[i].ch <- i
	}
	wg.Wait()
}

type7:(解决type3的顺序打印)

话外音：顺序打印的原因是，发送i(sendq存了一个goroutine)后立马被打印(读队列发现写队列有阻塞goroutine优势无缓冲channel立马copy值到读goroutine)

func worker(ch <-chan int, wg *sync.WaitGroup) {
	defer wg.Done()
	for {
		select {
		case n := <-ch:
			print(n)
		case <-time.NewTicker(time.Second).C:
			return
		}
	}
}

func main() {
	wg := new(sync.WaitGroup)
	ch := make(chan int)
	wg.Add(1)
    // 开一个goroutine收值
	go worker(ch, wg)
	for i := 0; i < 10; i++ {
		go func(i int) {
			ch <- i
		}(i)
	}
	wg.Wait()
}

type8:

func worker(ch <-chan int, wg *sync.WaitGroup) {
	defer wg.Done()
	for {
		select {
		case n := <-ch:
			print(n)
		case <-time.NewTicker(time.Second).C:
			return
		}
	}
}

func main() {
	wg := new(sync.WaitGroup)
	ch := make(chan int)
	wg.Add(10)
	for i := 0; i < 10; i++ {
        //开10个gouroutine收值
		go worker(ch, wg)
		go func(i int) {
			ch <- i
		}(i)
	}
	wg.Wait()
}

type9：

type worker struct {
	ch   chan int
	done func()
}

func generator(done func()) worker {
	w := worker{
		ch:   make(chan int),
		done: done,
	}
	go func() {
		for n := range w.ch {
			print(n)
			done()
		}
	}()
	return w
}

func main() {
	var (
		n    = 10
        // channel实现并发控制，struct{}占用0字节的内存空间(指向8字节zerobase全局变量)
		done = make(chan struct{})
		ws   = make([]worker, n)
	)

	for i := 0; i < n; i++ {
		ws[i] = generator(func() {
			done <- struct{}{}
		})
	}

	for i := 0; i < 10; i++ {
		ws[i].ch <- i
	}

	for i := 0; i < 10; i++ {
		<-done
	}
}

type10:下回分解...

​