Finding how many requests Node tries to handle at the same time for a single connection

client.js

const net = require('net');
const fs = require('fs');

var req = fs.readFileSync('./req.txt', { encoding: 'utf8' });

var socket = new net.Socket();
socket.connect(7001, '127.0.0.1', function() {
  console.log('Connected');
  var c = 50000;
  while (c --> 0)
    socket.write(req);
  socket.end();
});

req.txt

GET / HTTP/1.1
User-Agent: curl/7.35.0
Host: localhost:7001
Accept: */*

server.js

const http = require('http');
const util = require('util');

const backlog = 2047;
const hostname = '0.0.0.0';
const port = 7001;

var msg = util.format('Hello World %s %s ', port, process.pid);

var c = 0;
var h = 0;
http.createServer((req, res) => {
  ++h;

  if (++c % 2 !== 0)
    setTimeout(reply.bind(null, c), 3000);
  else
    reply(c);

  function reply(c) {
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end(msg + new Date() + ' ' + c);
    --h;
  }
}).listen(port, hostname, backlog);

setInterval(() => { console.log(h); }, 1000);