为什么一个输出有序一个输出无序？

• 代码片段一：输出结果有序

package main

import (
    "fmt"
    "time"
)

func main() {
    ch := make(chan struct{})
    for i := 0; i < 10; i++ {
        go func(num int) {
            for {
                <-ch
                fmt.Println(num)
            }
        }(i)
        time.Sleep(time.Millisecond)
    }
    time.Sleep(time.Second)
    for j := 0; j < 10; j++ {
        ch <- struct{}{}
        time.Sleep(time.Millisecond)
    }

    ch <- struct{}{}
    time.Sleep(time.Minute)
}

• 代码片段二：输出结果无序

package main

import (
    "fmt"
    "time"
)

func main() {
    ch := make(chan struct{})
    for i := 0; i < 10; i++ {
        go func(num int) {
            for {
                <-ch
                fmt.Println(num)
            }
        }(i)
        time.Sleep(time.Millisecond)
    }
    time.Sleep(time.Second)
    for j := 0; j < 10; j++ {
        ch <- struct{}{}
    }

    ch <- struct{}{}
    time.Sleep(time.Minute)
}