Here is an example of code that grows the memory for a while then eventually stabilizes

mem.js

var ChildProcess = require('child_process');

var maxMem = Math.round(process.memoryUsage().rss / (1024 * 1024)) * 2;

setInterval(function () {

    ChildProcess.exec('echo', function () {

        var mem = Math.round(process.memoryUsage().rss / (1024 * 1024));
        console.log(mem + 'M used');
    });
}, 100);