golang goroutine 骚操作系列 动态数量

type mg struct {
    max          int
    ch           chan func()
    pool         chan struct{}
    addGoRoutine *sync.Mutex
    clearTime    time.Duration
}

func newMg(max int, cleanTime time.Duration) mg {
    res := mg{max, make(chan func(), max), make(chan struct{}, max), &sync.Mutex{}, cleanTime}
    return res
}

func (itself *mg) exec(action func()) {
    // 写入的地方可以判断是否需要动态新增一个goroutine
    if len(itself.ch)+1 > len(itself.pool) && len(itself.pool) < itself.max {
        itself.checkNeedNewGoRoutine()
    }
    itself.ch <- action
}

func (itself *mg) checkNeedNewGoRoutine() {
    itself.addGoRoutine.Lock()
    defer itself.addGoRoutine.Unlock()
    if len(itself.pool) >= itself.max {
        return
    }
    go func(mgo *mg) {
        mgo.pool <- struct{}{}
        defer func() {
            <-mgo.pool
        }()
        timeout := time.After(itself.clearTime * time.Second)
        for {
            select {
            case action := <-mgo.ch:
                action()
                timeout = time.After(itself.clearTime * time.Second)
            case <-timeout:
                break
            }
        }
    }(itself)
}

func main() {
    fmt.Println("success")
    mgo := newMg(5, time.Second*3)
    for i := 1; i <= 100; i++ {
        mgo.exec(func(i int) func() {
            return func() {
                time.Sleep(time.Second)
                fmt.Println(time.Now().Second(), i)
            }
        }(i))
    }
    time.Sleep(time.Second * 2)
}

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