channel

package main

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

func main() {
    //顺序执行两个协程函数
    ch1 := make(chan string, 5)
    go testBoringWithChannelClose("boring!", ch1)
    ch2 := make(chan string, 5)
    go testBoringWithChannelClose("funning!", ch2)

    for b := range ch1 {
        go log.Printf("You say: %s", b)
    }

    for b := range ch2 {
        go log.Printf("You say: %s", b)
    }

}

func testBoringWithChannelClose(msg string, c chan string) {
    for i := 0; i < 20; i++ {
        c <- fmt.Sprintf("%s %d", msg, i)
        time.Sleep(time.Duration(rand.Intn(1e3)) * time.Millisecond)
    }
    fmt.Println(msg + "结束")
    close(c)
}

package main

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

func main() {


    //限制1024个协程数执行任务
    goNum1024Times()
}

// 控制1024个协程
func goNum1024Times() {
    var wg sync.WaitGroup
    ch := make(chan struct{}, 1024)
    for i := 0; i < 20000; i++ {
        wg.Add(1)
        ch <- struct{}{}
        go func() {
            defer wg.Done()
            fmt.Printf("%d\n", len(ch)) //打印通道的长度
            <-ch
        }()
    }
    wg.Wait()
}