小白想问一下关于单向通道的执行顺序

初学golang通道尝试了如下代码：

package main

import (
    "fmt"
    "time"
)

type Sender chan<- int

type Receiver <-chan int

func main() {
    var myChannel = make(chan int, (0))
    var number = 6
    go func() {
        var sender Sender = myChannel
        sender <- number    // 1
        sender <- number    // 2
        fmt.Println("Sent!")    //5
    }()
    go func() {
        var receiver Receiver = myChannel
        fmt.Println("Received!", <-receiver)    //3
    }()
    go func() {
        var receiver Receiver = myChannel
        fmt.Println("Received!", <-receiver)    //4
    }()
    time.Sleep(time.Second)
}

定义了一个非缓存myChannel后，在1处应该阻塞了，然后执行了3处，这时候通道里没数据应该执行2处之后阻塞了再执行4处，最后回到5处。 但实际结果是： Received! 6 Sent! Received! 6

这是为什么啊？有大神给解释一下吗