Golang时间。当其他goroutine新建一个结构并且该结构具有[] byte切片时，Tick会阻塞

I'm a golang newer, today I met a time.Tick problem, it lets me very confuse, please see the following code

var MAX_LEN4 = 5000

func main() {
    ch := make(chan struct{}, 100)
    var length uint = 0
    start := time.Now()

    var wg sync.WaitGroup
    wg.Add(1)
    go func() {
        tick := time.Tick(1 * time.Second)
        for {
            if length > MAX_LEN4+1 {
                break
            }
            <-tick
            fmt.Printf("Calculated: %d, time: %f
", length, time.Since(start).Seconds())

        }
        wg.Done()
    }()

    for ; length <= MAX_LEN4+1; length++ {
        go test3(length, &ch)
    }

    wg.Wait()
    fmt.Println("Test Finished")
}

func test3(l uint, ch *chan struct{}) {
    NewEncoder()
    // do something
}

type Encoder struct {
    stream []byte
    offset uint
    //bitLeft uint
}

func NewEncoder() Encoder {
    return Encoder{make([]byte, 4)}
}

when struct Encoder has []byte slice, the tick will block, the code will not print "Calculated..." content, and

<-tick

code will block there. like the above code

if struct Encoder doesn't a slice, but NewEncoder function returns a pointer, the tick doesn't work also, like the following code

func NewEncoder() *Encoder {
    return &Encoder{4)}
}

only struct Encoder doesn't have []byte slice and NewEncoder function return non pointer Encoder, the tick will work fine.

I try to replace the code:

<-tick 

by

time.Sleep(1 * time.Second) 

the effect is the same

I don't know why the code?