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('death', function(worker) {
            console.log('worker ' + worker.pid + ' died');
            cluster.fork();
        });
    }