無緩沖channel的內存泄漏問題：無緩沖channel在go程里done <- hardWork(job)時，如果外層執行完了后，done <- hardWork(job)寫操作<- 會一直阻塞

func requestWork(ctx context.Context, job interface{}) error {
    ctx, cancel := context.WithTimeout(ctx, time.Second*2)
    defer cancel()

    done := make(chan error)
    go func() {
        done <- hardWork(job)
    }()

    select {
    case err := <-done:
        return err
    case <-ctx.Done():
        return ctx.Err()
    }
}

func main() {
    const total = 1000
    var wg sync.WaitGroup
    wg.Add(total)
    now := time.Now()
    for i := 0; i < total; i++ {
        go func() {
            defer wg.Done()
            requestWork(context.Background(), "any")
        }()
    }
    wg.Wait()
    fmt.Println("elapsed:", time.Since(now))
    time.Sleep(time.Minute*2)
    fmt.Println("number of goroutines:", runtime.NumGoroutine())
}

? go run timeout.go
elapsed: 2.005725931s
number of goroutines: 1001