Articles tagged 'rails'

20 Small Reasons That Deploying a Rails App Is Hard

Are you deploying a Rails app? Here are lots of things you’ll probably have to watch for as you do… I’ve been writing an open-source gem and a (edited to add: now defunct) for-pay online class about this for months now. Let me share some things.

There are lots of big reasons that deploying a Rails app is hard. And lots of well-known, big tasks. But when you’re provisioning a server and deploying your application to it, lots of little things go wrong too.

I feel like the big things get a lot of respect already. Let’s look into some of the under-appreciated little things you have to get right in order to make a good deploy happen.

For starters, a lot of these small issues can require a lot of debugging. You know those two-line fixes that take three hours to find? Deployment is full of those. Here are some of mine to speed you on your way.

All Things Great and Small

Why Do They Say Rails Doesn't Scale?

If you’re new to Ruby on Rails, you may be new to the old debates (pro and con) about how “Rails doesn’t scale.” You might wonder why people say that, or where it came from.

The Rails logo and a scale with a circle-and-slash over top.

Let’s talk about that.

As far as “Rails Doesn’t Scale”, the main arguments go something like:

1) Ruby is slow, often up to 50x slower than C, so the server will eventually collapse.

This isn’t actually a scaling argument. But it’s true that Ruby is slow. Not 50x any more, closer to 5x (up to maybe 20x), but still, that’s not terribly speedy.

Rails doesn’t help Ruby here. A lot of the metaprogramming techniques it uses are among the slowest things Ruby does. I wrote a book about how Rails uses those techniques called Rebuilding Rails. They’re awesome, but they’re not speedy.

In practice, Ruby and Rails apps often “farm out” the slow stuff. The database is the traditional place to put the heavy lifting, but you’ll see Redis and Cassandra used in similar ways. Want Ruby to be fast? Call to something that isn’t Ruby, and is designed for speed :-)

Pure Ruby is quite slow, but just as scalable as any other language or library. It doesn’t get somehow slower as you add more.

2) Ruby/Rails leaks resources, so large or long-running projects don’t work

There was once more truth to this. Ruby had a few leaks and Rails exercised Ruby like nothing else. Also, ActiveRecord encourages large amounts of garbage per request, which was easy to mistake for leaks.

Digging Into the Rails Source

You’ve made it mostway through your free Ruby on Rails Internals class. Today we’ll be poking around the Rails source code. If you have money but not time, Rebuilding Rails lets you find a lot quickly… But in case you have more time, we’ll see where in the Rails source you can learn the same things...

Web Servers and Application Servers

A reader recently asked me why Ruby web app deploys usually have a web server (NGinX, Apache) and an application server (Unicorn, Thin, Puma, Racer, Mongrel, Passenger, Jakarta, TorqueBox or whatever I’ve forgotten this week).

Actually, he asked, “why do I need to run NGinX and Unicorn?” It’s a fair...

Understanding the Structure of Rails

Ruby on Rails is divided into several separate pieces. If you know what they are and what they do, you can use them individually. You can also look up documentation more easily, and you’ll know where to look for source code to a particular method, and which of several similarly-named methods does...

Rack and Session Store

A fellow asked me how he could store information per-user in Rack. This was my (brief) response:


Generally with the cookies object. Specifically, Rack has a “session”, which encodes a session identity into the cookies object, usually with some or all of your data.

You can also map from the session...

No More Requires

I hate all the “requires” at the front of Ruby files. I know what methods I’m using, but I have to write it in both places. Not exactly DRY. Rails skips them — you just use the classes you want. How can I automatically load my files like Rails does? Read on.

Ruby has methodmissing. When you call...

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