Node.js performance optimization

Question

I am new to performance optimization, and while I recognize Node.js may not be the most beginner friendly place to start, it's the task at hand.

The observation: simple JSON API requests take in the order of hundreds of milliseconds on a staging server with no load and <10 users in the database. Particularly, the call to /api/get_user is taking ~300ms.

To execute this code:

exports.get_user = function(req, res) {
  return res.json(req.user)
}

(Note: we store our sessions in Redis)

The stack:

• Node.js
• Express
• Redis
• Mongo

Where do I start?

Answer 1

While it might be an overkill for this small scenario, you might want to consider profiling. I found the nodetime.com service quite useful.

Answer 2

Passing the –-nouse_idle_notification flag will tell V8 to ignore idle notification calls from Node, which are requests to V8 asking it to run GC immediately, as the Node process is currently idle. Because Node is aggressive with these calls (efficiency breeds clean slates), an excess of GC may slow down your application. Note that using this flag does not disable GC; GC simply runs less often. In the right circumstances this technique can increase performance.