bench.js

var proxy = require('./http-proxy'),
    http  = require('http');

http.createServer(function (req, res){
  res.writeHead(200, {'Content-Type': 'text/plain'});
  res.write('request successfully proxied to: ' + req.url + '\n' + JSON.stringify(req.headers, true, 2));
  res.end();
}).listen(9000);

proxy.createServer(9000, 'localhost').listen(8000);

gistfile2.txt

http-proxy.js

var http = require('http'),
    sys  = require('sys');

exports.createServer = function createServer (port, host) {
  return new HttpProxy({
    port: +port,
    host: host || '0.0.0.0'
  });
};

var ClientPool = function ClientPool (port, host, max_clients) {
  this.port        = +port;
  this.host        = host;
  this.max_clients = max_clients || 200;
  this.clients     = [];
  this.free        = [];

  var pointer = 0;
  Object.defineProperty(this, 'pointer', {
    enumerable: false,
    get:        function () {
      var ret = pointer;
      ++pointer;
      if (pointer >= this.clients.length) pointer = 0;
      return ret;
    }
  });

  return this;
};

ClientPool.prototype.request = function allocRequest (method, path, headers) {
  var client, request, $ = this;

  if (this.clients.length >= this.max_clients) {
    request = this.clients[this.pointer].request(method, path, headers);
  } else if (!(client = this.free.pop())) {
    client = http.createClient(this.port, this.host);
    this.clients.push(client);
    request = client.request(method, path, headers);
    client.on('close', function () {
      if (~$.free.indexOf(client)) return;
      $.free.push(client);
    });
  } else {
    request = client.request(method, path, headers);
  }

  return request;
};

var HttpProxy = exports.HttpProxy = function HttpProxy (options) {
  this.client_pool = new ClientPool(options.port, options.host);
  http.Server.call(this);

  this.on('request', this.onRequest);
  return this;
};

HttpProxy.prototype = Object.create(http.Server.prototype);

HttpProxy.prototype.onRequest = function onRequest (e_request, e_response) {
  var i_request = this.client_pool.request(e_request.method,
                    e_request.url, e_request.headers);

  i_request.connection.on('error', function (error) {
    error = 'An error occurred: ' + sys.inspect(error);

    e_response.writeHead(200, {
      'Content-Type':   'text/plain',
      'Content-Length': error.length
    });
    if (e_request.method === 'HEAD') error = null;

    e_response.end(error);
  });

  i_request.on('response', function (i_response) {
    // Pump response
    e_response.writeHead(i_response.statusCode, i_response.headers);
    sys.pump(i_response, e_response);
  });

  sys.pump(e_request, i_request);
};