Rage compared to Falcon

[bradgessler]

I'm trying to understand the difference between Falcon & Rage, and their respective primitives, which I think is Ruby Async and iodine.

Are there any quick comparisons for this libraries? Existing articles (I couldn't find anybody)? Benchmarks?

I'm guessing contributors to this project probably know some of the differences.

[rsamoilov]

Thanks for the great question! It completely makes sense why comparing these two can be a bit tricky, as they approach Ruby concurrency from different angles.

High-Level Difference

Falcon & Async: Async is a concurrency library (a building block), and Falcon is a Rack-compatible web server built on top of it. You build your application using a framework like Rails or Sinatra, and then you use Falcon as the web server to run it.

Rage & Iodine: Rage is an integrated runtime - the server and the framework are tightly integrated by design. Rage is built on top of a custom fork of Iodine, which I maintain and treat as an internal part of the framework. Also, Rage does not use Async. Instead, it relies on its own fiber scheduler.

What Makes Them Fundamentally Different

The biggest difference is scope and philosophy:

• With Falcon, you are plugging an existing Rack app into a server.
• With Rage, there is no separate server. You are building your application inside the Rage framework. Because the server and framework are fused together, Rage can optimize the entire request lifecycle. It also provides "batteries-included" framework features like code loading, logging, observability, an event system, and background jobs, all wrapped in a familiar Rails-like syntax.

Falcon

• Rack-compatible
• Works with Rails, Hanami, Sinatra, etc.
• Async is a general-purpose concurrency toolkit
• Server and framework are decoupled

Rage

• Server is part of the framework (not swappable)
• Own request/response lifecycle
• Own router, controller layer, observability
• Designed around async I/O from the ground up

Async is a low-level concurrency toolkit that can power many systems. Rage is a complete system built on top of optimized primitives.

Respective Primitives

If by primitives you mean concurrency primitives:

• Async exposes Tasks, Queues, structured concurrency concepts
• Rage exposes controllers, jobs, WebSockets, and hides the IO/event loop layer inside the runtime

So Async exposes the primitives. Rage encapsulates the primitives. That's probably the cleanest way to describe it.

Benchmarks

There isn't a direct benchmark between Rage and Falcon+Async, because they sit at different layers of the stack. Instead, it's more accurate to compare Rage against other frameworks, like Rails or Sinatra.

This is what the TechEmpower benchmarks do. In fact, if you look at the TechEmpower results, you'll notice an entry for Rails+Falcon, which highlights how Falcon is used as a server to run an existing framework, whereas Rage is measured on its own.

Because Rage controls the entire stack, it minimizes overhead and performs strongly in high-throughput scenarios. You can check out the performance data here:

• TechEmpower Benchmarks
• WebSocket Benchmarks