select 与 time.After 配合使用的问题

今天在工做中发现了一个有趣的现象。

在一个select中设定了两个定时器，原本预计哪一个定时器到达就运行相应指令的，可是发现最终只有时间最短的定时器一直获得执行，其它定时器彻底没有获得执行。

package main

import (
"fmt"
"time"
)

func main(){
    for i:=0; i< 3;i ++ {
        select{
            case <-time.After(7*time.Second):
                fmt.Println("1 second")
                
            case <-time.After(5*time.Second):
                fmt.Println("8 seconds")
        }
    }
}

服务器输出是：

8 seconds
8 seconds 8 seconds

在stackoverflow上有人提到了，time.After每次都会返回一个新的channel，因此select不可能监测到新产生的channel：
https://stackoverflow.com/questions/39212333/how-can-i-use-time-after-and-default-in-golang

package main

import (
"fmt"
"time"
)

func main(){
    count := 0
    timeout1 := time.After(7*time.Second)
    timeout2 := time.After(5*time.Second)
    for i:=0; i< 36; i++{
        select{
            case <-timeout1:
                fmt.Println(count, "7 second")
                
            case <-timeout2:
                fmt.Println(count, "5 seconds")
                
            default:
                fmt.Println(count, "Just wait")
                
        }
        count++
        time.Sleep(1*time.Second)
    }
}

0 Just wait
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