index.js

var http = require('http');
var ForeverAgent = require('forever-agent');

var server = http.createServer(function (req, res) {
    console.log('Server got request', req.url);
    res.write(req.url);

    // Get time to all async callbacks to be processed
    setTimeout(function () {
        res.end();
    }, 50);
});

server.listen(3000);


var agent = new ForeverAgent({
    maxSockets: 2
});

function runRequest(path, callback) {
    var request = http.request({
        method: 'GET',
        hostname: '127.0.0.1',
        port: 3000,
        path: path,
        agent: agent,
    });

    request.on('socket', function (socket) {
        if (!socket.__requestId) {
            socket.__requestId = path;
            console.log('Request uses fresh new socket for %s', path);
        } else {
            console.log('Request uses old socket for %s from %s',
                path, socket.__requestId);
        }
    });

    request.on('response', function (res) {
        var data = '';
        res.on('data', function (chunk) {
            data += chunk;
        });
        res.on('end', function () {
            callback(null, data);
        });
        res.on('error', function (error) {
            callback(error);
        });
    });

    request.on('error', function (error) {
        callback(error);
    });

    console.log('Client requests GET', path);
    request.end();
    return request;
}

function run() {
    console.log('Start requests');

    var queue = [
        '/hello-1',
        '/hello-2',
        '/hello-3',
        '/hello-4',
        '/hello-5'
    ];

    function exit(err) {
        if (err) {
            console.error('Error:', err);
        }
        console.log('Exit');
        server.close();
    }

    function processQueue() {
        var path = queue.shift();
        if (path) {
            var req = runRequest(path, function (error, data) {
                if (error) {
                    console.error(error);
                } else {
                    console.log('Client got response for GET %s: %s',
                        path, data);
                }
                processQueue();
            });
            
            // Unlucky /hello-2 has been randomly chosen to be destroyed
            if (path === '/hello-2') {
                req.on('response', function (res) {
                    console.log('Destroying socket for %s', path);
                    req.socket.destroy();
                });
            }
        } else {
            exit(null);
        }
    }

    processQueue();
}

server.on('listening', run);