demonstrating ResponseWriter.Write blocking

instructions

# run a server
./a.out -server

# run a client
./a.out

# see that the server does not finish writing right away

main.go

package main

import (
	"flag"
	"fmt"
	"io"
	"log"
	"net/http"
	"time"
)

func server() (err error) {
	buf := make([]byte, 1<<12)

	http.HandleFunc("/", func(w http.ResponseWriter, _ *http.Request) {
		start := time.Now()
		defer func() {
			fmt.Println("elapsed", time.Now().Sub(start))
		}()

		for i := 0; i < 1000; i++ {
			n, err := w.Write(buf)
			if err != nil {
				fmt.Println(err)
				return
			}

			fmt.Println("wrote", i, n)
		}
	})

	err = http.ListenAndServe(":8000", nil)
	if err != nil {
		err = fmt.Errorf("listen and serve: %w", err)
		return
	}

	return
}

func client() (err error) {
	resp, err := http.Get("http://localhost:8000")
	if err != nil {
		err = fmt.Errorf("get: %w", err)
		return
	}

	var (
		buf []byte
		n   int
	)

	for {
		buf = make([]byte, 1<<10)

		fmt.Println("reading")
		n, err = resp.Body.Read(buf)
		if err != nil {
			if err == io.EOF {
				err = nil
				return
			}

			err = fmt.Errorf("read: %w", err)
			return
		}

		fmt.Println("read", n)
		time.Sleep(10 * time.Millisecond)
	}

	return
}

var (
	isServer = flag.Bool("server", false, "be a server?")
)

func main() {
	var err error

	flag.Parse()

	if *isServer {
		err = server()
	} else {
		err = client()
	}

	if err != nil {
		log.Fatal(err)
	}

}