通过使用channel 限制goroutines数量

func TestLimitRoutines(t *testing.T) {
    ch := make(chan bool, 4)
    taskCnt := math.MaxInt
    for i := 0; i < taskCnt; i++ {
        ch <- true
        go func(ch <-chan bool, num int) {
            fmt.Println("go func ", i, " goroutine count = ", runtime.NumGoroutine())
            <-ch
        }(ch, i)
    }
    time.Sleep(time.Second * 10)

}

package test

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

var wg sync.WaitGroup

func TestLimitRoutines(t *testing.T) {
    ch := make(chan int)
    for i := 0; i < 4; i++ {
        go func(ch chan int) {
            for task := range ch {
                defer wg.Done()
                fmt.Println(fmt.Sprintf("go func  %d  goroutine count =  %d", task, runtime.NumGoroutine()))
            }
        }(ch)
    }

    for i := 0; i < math.MaxInt; i++ {
        wg.Add(1)
        ch <- i
    }
    wg.Wait()
}