使用channel控制并发数

package concurrent_test

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

func init() {
    rand.Seed(time.Now().UnixNano())
}

// 使用channel控制并发数

var lst = []string{
    "whw1", "whw2", "whw3", "whw4", "whw5", "whw6", "whw7", "whw8", "whw9",
    "whw10", "whw11", "whw12", "whw13", "whw14", "whw15", "whw16", "whw17", "whw18", "whw19",
}

func TestChanControlGos(t *testing.T) {

    var wg sync.WaitGroup
    limitChan := make(chan struct{}, 3) // 最多同时有3个协裎同时工作

    for _, item := range lst {
        wg.Add(1)
        limitChan <- struct{}{}
        // 注意: 如果要用lst中的元素，一定要定义在func下并当作参数传入!
        go func(s string) {
            defer wg.Done()
            consumeStr(s, limitChan)
        }(item)
    }

    wg.Wait()
    fmt.Println("主协裎结束......")

}

func consumeStr(name string, limitCh chan struct{}) {
    defer func() {
        <-limitCh
    }()
    time.Sleep(time.Duration(rand.Intn(2)) * time.Second) // 模拟延迟
    fmt.Println("name: ", name)
}

～～～