net round robin

base.js

var cluster = require('cluster');
var assert = require('assert');
var http = require('http');
var N = 4;  // # of workers

if (cluster.isWorker)
  worker();
else
  master();

function master() {
  for (var i = 0; i < N; ++i) {
    cluster.fork().on('message', onmessage);
  }
  var times = [];
  function onmessage(msg) {
    times.push(msg);
    if (times.length === N) onexit();
  }
  function onexit() {
    var total = { pid: 0, sys: 0, user: 0 };
    for (var i = 0; i < times.length; ++i) {
      total.sys += times[i].sys;
      total.user += times[i].user;
      console.log('%j', times[i]);
    }
    console.log('%j', total);
  }
  process.on('SIGUSR2', function() {
    // ignore
  });
}

function worker() {
  var reply = 'ACK from ' + process.pid + '\n';
  var headers = { 'Content-Length': '' + reply.length };
  var server = http.createServer(function(req, res) {
    res.writeHead(200, headers);
    res.end(reply);
  });
  server.listen(8000);
  process.on('SIGUSR2', function() {
    var u = require('rusage').getrusage();
    var user = u.ru_utime.sec * 1e6 + u.ru_utime.usec;
    var sys = u.ru_stime.sec * 1e6 + u.ru_stime.usec;
    // convert to millis
    user /= 1e3;
    sys /= 1e3;
    process.send({ pid: process.pid, sys: sys, user: user });
    process.exit();
  });
}

bench.sh

#!/bin/sh

cd `dirname $0`

echo "BASE"
node base.js &
sleep .5
ab -k -c 100 -n 100000 http://127.0.0.1:8000/ | grep -A 3 'Requests per second'
pkill -USR2 node

sleep .5

echo "ROUND ROBIN"
node rr.js &
sleep .5
ab -k -c 100 -n 100000 http://127.0.0.1:8000/ | grep -A 3 'Requests per second'
pkill -USR2 node

package.json

{
  "dependencies": ["rusage"]
}

rr.js

var TCP = process.binding('tcp_wrap').TCP;
var fork = require('child_process').fork;
var assert = require('assert');
var events = require('events');
var http = require('http');
var net = require('net');
var L = require('_linklist');
var N = 4;  // # of workers

if (process.argv[2] === 'worker')
  worker();
else
  master();

function master() {
  var workers = new events.EventEmitter;
  var times = [];
  var n = 0;

  L.init(workers);
  workers.setMaxListeners(9999);
  for (var i = 0; i < N; ++i) {
    var worker = fork(__filename,
                      ['worker'],
                      {'stdio': ['ignore','ignore','ignore','ipc']});
    L.append(workers, worker);
    worker.setMaxListeners(9999);
    worker.once('message', function(msg) {
      assert.equal(msg, 'ready');
      if (++n == N) start();
    });
    worker.on('message', function(msg) {
      if (typeof msg !== 'object') return;
      times.push(msg);
      if (times.length === N) onexit();
    });
  }

  function start() {
    net.createServer(onconnection).listen(8000);
    var handles = {};  // Pending (i.e. not yet distributed) handles.
    L.init(handles);
    function onconnection(conn) {
      var handle = conn._handle;
      handle.readStop();
      conn._handle = null;
      conn.destroy();
      if (L.isEmpty(workers)) return L.append(handles, handle);
      var worker = L.shift(workers);
      send(worker, handle);
    }
    function send(worker, handle) {
      worker.once('message', function(msg) {
        if (msg !== 'ack') return;
        handle.close();
        if (L.isEmpty(handles)) return L.append(workers, worker);
        var handle_ = L.shift(handles);
        send(worker, handle_);
      });
      worker.send('handle', handle);
    }
  }

  function onexit() {
    var total = { pid: 0, sys: 0, user: 0 };
    for (var i = 0; i < times.length; ++i) {
      total.sys += times[i].sys;
      total.user += times[i].user;
      console.log('%j', times[i]);
    }
    console.log('%j', total);
    process.exit();
  }
  process.on('SIGUSR2', function() {
    // ignore
  });
}

function worker() {
  var reply = 'ACK from ' + process.pid + '\n';
  var headers = { 'Content-Length': '' + reply.length };
  var server = http.createServer(function(req, res) {
    res.writeHead(200, headers);
    res.end(reply);
  });
  process.on('message', function(msg, handle) {
    assert.equal(msg, 'handle');
    var conn = new net.Socket({
      'handle': handle,
      'readable': true,
      'writable': true,
    });
    assert.equal(conn.readable, true);
    assert.equal(conn.writable, true);
    server.emit('connection', conn);
    process.send('ack');
  });
  process.send('ready');
  process.on('SIGUSR2', function() {
    var u = require('rusage').getrusage();
    var user = u.ru_utime.sec * 1e6 + u.ru_utime.usec;
    var sys = u.ru_stime.sec * 1e6 + u.ru_stime.usec;
    // convert to millis
    user /= 1e3;
    sys /= 1e3;
    process.send({ pid: process.pid, sys: sys, user: user });
    process.exit();
  });
}