当我添加multipart.NewWriter（body_buf）时，程序不会停止

package main

import (
    "fmt"
    "mime/multipart"
    "bytes"
)

var channel chan string = make(chan string)

func recognize(file_path string) {
    body_buf := &bytes.Buffer{}
    fmt.Println(body_buf)

    send_writer := multipart.NewWriter(body_buf)
    fmt.Println(send_writer)
}

func loop() {
    for i := 0; i < 10; i++ {
        channel <- "dd"
    }
}


func main() {
    go loop()
    for v :=  range channel {
        fmt.Println(len(channel), v)
    }
}

the program will not stop, even i don't call the recognize function, i don't know why, how to explain that

when i remove the

send_writer := multipart.NewWriter(body_buf)

the program will stop and get fatal error: deadlock

what make it difference, who can tell me

The program will not stop as you never close the channel and thus the range loop over it will not terminate. Close the channel in loop like

func loop() {
    for i := 0; i < 10; i++ {
        channel <- "dd"
    }
    close(channel)
}

and it should stop.