Golang关闭需要结束的goroutine

package main

import (
    "fmt"
    "math/rand"
    "time"
)

func main() {
    newRandStream := func(done <-chan interface{}) <-chan int {
        randStream := make(chan int)
        go func() {
            defer fmt.Println("randstream closeed, exited!")
            defer close(randStream)
            for {
                select {
                case randStream <- rand.Int():
                case <-done:
                    return
                }
            }
        }()
        return randStream
    }

    done := make(chan interface{})
    randStream := newRandStream(done)

    fmt.Println("Read 3 rand ints: ")
    for i := 1; i <= 3; i++ {
        fmt.Printf("%d %d \n", i, <-randStream)
    }

    close(done)
    time.Sleep(1 * time.Second)
}

程序输出如下，