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?

There really isn't enough info here to guess what issue you are hitting. — loganfsmyth
– loganfsmyth, Commented Dec 20, 2013 at 3:53
Please specify where physically your services (node, redis, mongo) appear. Provide a larger piece of code which is actually executed. Also it is usually easy to identify the time taking operation by adding console.log(new Date()) in script which is executed. — igorpavlov
– igorpavlov, Commented Dec 21, 2013 at 0:06
@jibsales I should have mentioned I'm using Express / PassportJS (and mongoose). Here's passport.deserializeUser: jsfiddle.net/Y2vJS — max
– max, Commented Dec 21, 2013 at 1:31
@igorpavlov are you asking what order redis / mongo / appear in app.js / what other middleware the request traverses before hitting exports.get_user ? — max
– max, Commented Dec 21, 2013 at 2:05

serkan · Accepted Answer · 2015-10-28 16:48:32Z

1

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.

answered Oct 28, 2015 at 16:48

serkan

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Comments

Jesus Ruiz · Accepted Answer · 2013-12-20 07:00:33Z

0

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

answered Dec 20, 2013 at 7:00

Jesus Ruiz

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3 Comments

max Over a year ago

I ran a transaction profile on /api/get_user on nodetime and got 12.9ms: nodetime screenshot. But the same request on chrome dev tools shows 607ms: dev tools screenshot. Since nodetime is just measuring how long it takes for node to generate the request, should I assume the difference is the time it takes for the request to travel over the open internet?

Jesus Ruiz Over a year ago

Yes that is a reasonable assumption. I don't know the details about your deployment topology. There might be latency on your line or simply you might be spending time in dns resolution. In addition you might want to measure a stream of continuous request discarding the first few, which tend to take longer due to loading time.

max Over a year ago

I discovered nginx's limit_req directive was too restrictive, and responsible for the majority of the delay. Thanks.

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