Error [ERR_STREAM_WRITE_AFTER_END]: write after end [npm-request with socket.io]

Question

On my server side I have socket server listening and in my own laptop I have socket.io-client service and whenever I turn on both they are connecting.

And when other people request to my server, server sends that request via socket to my laptop and my laptop gets data from localhost using npm-request and gives back the returned data to the server then server show that information to the client.

And here is the error on my server side:

/*

throw er; // Unhandled 'error' event
      ^

**Error [ERR_STREAM_WRITE_AFTER_END]: write after end**
    at write_ (_http_outgoing.js:572:17)
    at ServerResponse.write (_http_outgoing.js:567:10)
    at Socket.<anonymous> (/public_html/api/index.js:37:9)
    at Socket.emit (events.js:187:15)
    at /public_html/api/node_modules/socket.io/lib/socket.js:528:12
    at process._tickCallback (internal/process/next_tick.js:61:11)
Emitted 'error' event at:
    at writeAfterEndNT (_http_outgoing.js:634:7)
    at process._tickCallback (internal/process/next_tick.js:63:19)

    */

server side code:

var http = require('http');
var fs = require('fs');
var socket_g=null, numOfUsers=0;
var url = require('url'),qs = require('querystring');

var server = http.createServer(function(req, res) {
    if(numOfUsers!=0){
          var urlParts = url.parse(req.url, true),
         urlParams = urlParts.query, 
         urlPathname = urlParts.pathname,
         body = '',
         reqInfo = {};

          req.on('data', function (data) {
            body += data; 
          });

          req.on('end', function () {
            reqInfo.urlPathname = urlPathname; 
            reqInfo.urlParams = urlParams; 
            reqInfo.body = qs.parse(body); 
            reqInfo.urlParts = urlParts;
            console.log(reqInfo.urlPathname)
              socket_g.emit('event', { "path": reqInfo.urlPathname});
          });

        socket_g.on('data',function(data){
              console.log(data.c)
              if(data.c=='application/x-httpd-php' || data.c=='/'){
                    res.writeHead(200, { 'Content-Type': 'text/html' });
                    res.write(data.data);
                    res.end();
              }else{
                    res.writeHead(200, { 'Content-Type': data.c });
                    res.write(data.data);
                    res.end();
              }         
        });
    }else{
        res.writeHead(200, { 'Content-Type': 'text/html' });
            res.end("<h2>There is no client connected!</h2>");
    }
});

var io = require('socket.io').listen(server);
io.sockets.setMaxListeners(0);

io.sockets.on('connection', function (socket) {
    /*console msg*/
    console.log('user connected!');
    /*console msg*/
    socket.setMaxListeners(0);
    numOfUsers++;
    socket_g=socket;
    socket.on('disconnect', function(){
        numOfUsers++;
        /*console msg*/
        console.log('user disconnected');
        /*console msg*/
    });
});


server.listen(3333);

And belove my client side code, which is working on my laptop

Answer 1

Problem:

You are listening to the 'data' event even after returning the response.

Solution:

Use .once to listen to the event for one time for that one particular request.

socket_g.once("data", function(data) {