#goroutine 通过chan控制new速率

package main

import (
    "fmt"
    "math"
    "runtime"
)

func busi(ch chan bool, i int) {

    fmt.Println("go func ", i, " goroutine count = ", runtime.NumGoroutine())
    <-ch
}

func main() {
    //模拟用户需求业务的数量
    task_cnt := math.MaxInt64
    //task_cnt := 10

    ch := make(chan bool, 3) // 通过channel

    for i := 0; i < task_cnt; i++ {

        ch <- true

        go busi(ch, i)
    }

}
// 上边 单 ch 控制不了。 改成10可看出来 

与 sync.waitGroup 结合方式

package main

import (
    "fmt"
    "math"
    "sync"
    "runtime"
)

var wg = sync.WaitGroup{}

func busi(ch chan bool, i int) {

    fmt.Println("go func ", i, " goroutine count = ", runtime.NumGoroutine())

    <-ch

    wg.Done()
}

func main() {
    //模拟用户需求go业务的数量
    task_cnt := math.MaxInt64

    ch := make(chan bool, 3)

    for i := 0; i < task_cnt; i++ {
		wg.Add(1)

        ch <- true

        go busi(ch, i)
    }

	  wg.Wait()
}