Simple Node.js Cluster database access code

var http = require('http');
var mysql = require('mysql2');
var async = require('async');
var connection = mysql.createConnection({ user: 'benchmark', database: 'benchmark', password: 'benchpass'});
var cluster = require('cluster');
var numCPUs = require('os').cpus().length;

if (cluster.isMaster) {
    // Fork workers.
    for (var i = 0; i < numCPUs; i++) {
        cluster.fork();
    }

    cluster.on('exit', function (worker, code, signal) {
        console.log('worker ' + worker.process.pid + ' died');
    });
} else {
    http.createServer(function (req, res) {
        res.writeHead(200, {'Content-Type': 'text/html'});
        connection.query('SELECT * FROM users LIMIT 100;', function (err, rows) {
            if (err) {
                throw new Error('Connection failed');
            }
            var table = '<table><tr><th>id</th><th>username</th><th>password</th><th>banking account</th><th>phone number</th></tr>';
            async.forEach(rows, function (row, callback) {
                table += '<tr><td>' + row.id + '</td><td>' + row.username + '</td><td>' + row.password + '</td><td>' + row.banking_account + '</td><td>' + row.phone_number + '</td></tr>';
                callback();
            }, function (err) {
                if (err) {
                    throw new Error('Async failed!');
                }
                table += '</table>';
                table += '<div style="color:red">Hello from cluster worker: ' + cluster.worker.id + '</div>';
                res.end(table);
            });
        });
    }).listen(9615);
    console.log("Server running at http://localhost:9615 on cluster worker number " + cluster.worker.id);
}

Benchmark results:
ab -n 100000 -c 200 http://127.0.0.1:9615/
This is ApacheBench, Version 2.3 <$Revision: 1528965 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/

Benchmarking 127.0.0.1 (be patient)
Completed 10000 requests
Completed 20000 requests
Completed 30000 requests
Completed 40000 requests
Completed 50000 requests
Completed 60000 requests
Completed 70000 requests
Completed 80000 requests
Completed 90000 requests
Completed 100000 requests
Finished 100000 requests


Server Software:
Server Hostname:        127.0.0.1
Server Port:            9615

Document Path:          /
Document Length:        11001 bytes

Concurrency Level:      200
Time taken for tests:   11.692 seconds
Complete requests:      100000
Failed requests:        0
Total transferred:      1110100000 bytes
HTML transferred:       1100100000 bytes
Requests per second:    8553.03 [#/sec] (mean)
Time per request:       23.384 [ms] (mean)
Time per request:       0.117 [ms] (mean, across all concurrent requests)
Transfer rate:          92721.84 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:        0    0   0.1      0       3
Processing:     0   23  16.8     20     113
Waiting:        0   23  16.8     20     113
Total:          0   23  16.8     20     113

Percentage of the requests served within a certain time (ms)
  50%     20
  66%     28
  75%     34
  80%     37
  90%     45
  95%     52
  98%     63
  99%     80
 100%    113 (longest request)