access.js

var http = require('http')

// var times = parseInt(process.argv[2] || 5, 10)

var urls = [
    '/enq/1',
    '/enq/999999',
    '/enq/2',
    '/enq/3',
    '/enq/4'
]
urls.forEach(function(u) {
    var url = 'http://localhost:3005' + u
    console.log('GET:', url)
    http.cat(url, function(err, val) {
        if (err) {
            console.log('E:', err)
        }
        console.log(val)
    })
})

app.js

var express = require('express')
var redis = require('redis')
var spawn = require('child_process').spawn

var app = express.createServer()
var redisc = redis.createClient()
var rediscp = redis.createClient()

var port = 3005
var q_key = 'worker_q'
var rq_key = 'worker_rq'

var rq = {}
redisc.del(rq_key, function() {
    run_workers(3)
    run_server()
    get_result()
})

function get_result() {
    // console.log('server: blpop', rq_key)
    rediscp.blpop(rq_key, 0, function(err, val) {
        if (val) {
            var j = JSON.parse(val[1])
            var callback = rq[j['qid']]
            if (callback) {
                callback(j['val'])
                delete rq[j['qid']]
            }
        }
        setTimeout(get_result, 100)
    })
}

function run_workers(size) {
    for (var i = 1; i <= size; i++) {
        spawn_worker(i)
    }
}

function spawn_worker(i) {
    child = spawn('node', ['worker.js', q_key, rq_key])
    // console.log('spawn worker:', child.pid)
    child.stdout.on('data', function (data) {
        process.stdout.write('worker' + i + ': ' + data);
    })
    child.stderr.on('data', function (data) {
        process.stdout.write('worker' + i + ': ' + data)
    })
    child.on('exit', function (code) {
        process.stdout.write('worker' + i + ': exited with code ' + code);
    })
}

function run_server() {
    var i = 0;
    app.get('/', function(req, res) {
        redisc.lrange(q_key, 0, -1, function(err, val) {
            res.send(JSON.stringify(val))
        })
    })
    app.get('/enq/:id', function(req, res) {
        console.log('server:', req.url)
        var qid = 'q_' + (i++)
        var val = { qid: qid, id: req.param('id') || 'none' }
        rq[qid] = function(val) {
            res.send(val || '')
        }
        redisc.lpush(q_key, JSON.stringify(val), function(err, val) {
            if (err) {
                console.log('E', err)
            }
        })
    })
    app.listen(port)
    console.log('server: ' + port)
}

worker.js

var redis = require('redis')

var redisc = redis.createClient()
var q_key = process.argv[2] || 'worker_q'
var rq_key = process.argv[3] || 'worker_rq'

function foo(number) {
    function calc(a, b){
        for(var c=0;c < b;c++)
            a += 1 - 2*(c%2);
        return a;
    }
    var n = 0, c;
    for(c=0;c<number;c++){
        n = calc(n, c);
    }
    return n
}

function work() {
    console.log('blpop')
    redisc.blpop(q_key, 0, function(err, val) {
        try {
            var j = JSON.parse(val[1])
            var n = foo(j['id'])
            var r = { qid: j['qid'], val: '' + n || 'none' }
            redisc.lpush(rq_key, JSON.stringify(r))
            setTimeout(work, 100)
        }
        catch(e) {
            console.lot(e)
            setTimeout(work, 5000)
        }
    })
}
work()