Question

I have a node.js script that continuously requests a page, sort of like a cron job.

However, after a few minutes Node starts to use a lot of CPU (up to 70%) and memory (up to 200mb).

What is wrong with my script?

function cron(path)
{
    var http = require('http');
    var site = http.createClient(443, 'www.website.com', true);
    var request = site.request('GET', path, {'host': 'www.website.com'});
    request.end();

    request.on('response', function (response) {

        setTimeout(function(){cron(path)},15000);
    });


}

cron('/path/to/page');

Answer 1

request.on('response', function (response) {
    setTimeout(function(){cron(path)},15000);
});

For every response you create a new cron job. Log your responses. If your getting more then 1 from your request then your exponantially creating more cron jobs.

Your creating a function() {} with a reference to path. So the entire scope state is kept. you want to free memory by adding this:

var site = null;
var request = null;

Your calling require("http") inside a function rather then outside in module scope. You only need to get http once so place at the top of your file in module scope.

var http = require('http');
var site = http.createClient(443, 'www.website.com', true);
function cron(path)
{

    var request = site.request('GET', path, {'host': 'www.website.com'});
    request.end();

    var once = true;
    request.on('response', doIt);

    function doIt(response) {
        if (!once) {
            once = null;
            doIt = function() {};
            setTimeout(function(){cron(path)},15000);
        }
    });

    site = null;
    request = null;
}

cron('/path/to/page');