Senior & Expert RoR Developers Discussion Forum by Nyros Technologies

[swaminadhan]

There have been long debates on Rails performance. Rails can really slow down when your application deals with a lot of File exchange or concurrent connections. That is what Merb has been designed for. Ezra Zygmuntowicz, from Engine Yard, started working on Merb (Mongrel+Erb). Ezra originally tried to optimize Rails to make it more threadsafe, but at the end it was easier to make a new framework than trying to change ActionPack, (the View and Controller parts of Rails).

Merb is similar to Rails in many ways. What differentiates Merb from Rails is:

* It has no cgi.rb
* It has a clean room implementation of ActionPack
* It is threadsafe with configurable Mutex Locks (Routing is also threadsafe)
* It has been designed favoring simplicity and clarity over magic
* A light core framework easy to extend through hacks

The key differences are:

* No auto-render. The return value of your controller actions is what gets returned to client. You have to explicitly call a render method if you want it.
* Merb's render method just returns a string, allowing for multiple renders and additional flexibility over similar functionality in Rails
* PartControllers allow for encapsulated apps without big performance cost