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

Question

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

Answer 1

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.