Phusion Passenger is an Apache and Nginx module for deploying Ruby and Python web applications. It has a strong focus on ease of use, stability and performance. Phusion Passenger is built on top of tried-and-true, battle-hardened Unix technologies, yet at the same time introduces innovations not found in most traditional Unix servers. Since mid-2012, it aims to be the ultimate polyglot application server.

In the announcement for Phusion Passenger 4.0.0 beta 1, we introduced a myriad of changes such as support for multiple Ruby versions, Python WSGI support, multithreading (Enterprise only), improved zero-copy architecture, better error diagnostics and more. And as we promised, the story would not end there. A commit has just landed in our Github repository for JRuby (1.7.0 required) and Rubinius support!

JRuby: the past and the current state of affairs

JRuby is an excellent Ruby implementation for the JVM, and in the past few years they have been doing a great job with regard to compatibility and performance. But for a long time, application server support for JRuby had been limited:

While Mongrel and Thin had limited JRuby support, these setups have not been very popular. Since so few people use these setups, their caveats are not very well known.

Unicorn does not support JRuby at all because it was designed to take advantage of Unix features, which JRuby does not (and cannot) always support well.

Phusion Passenger was in the same position: we used too many Unix features and were not able to support JRuby well.

Goliath does not seem to have official support for JRuby thanks to the unknown status of EventMachine’s Java support.

So the only options left were J2EE app servers such as JBoss, Tomcat, GlassFish and TorqueBox; as well as the recently developed Puma, which is almost pure Ruby.

Thanks to the new ApplicationPool and Spawner architecture in Phusion Passenger 4, we’re now able to support JRuby with ease. Because a lot of code has been moved into C++, we no longer need the Ruby implementation to support Unix features. We only needed an hour to add support for JRuby.

Phusion Passenger vs J2EE

With Phusion Passenger’s support for JRuby, you don’t need to learn about J2EE deployment. Using JRuby on Phusion Passenger is very straightforward: set PassengerRuby to your JRuby command, point the virtual host’s document root to your application’s ‘public’ directory, and you’re done.

With Phusion Passenger Enterprise, JRuby users get to enjoy all the enterprise features such as multithreading, rolling restarts, deployment error resistance, time and memory usage limiting, and more.

Rubinius is impressive as well

We remember that back in the days, Rubinius was quite slow during startup and did not support MRI native extensions. Fast forward to 2012, and what we find is a very impressive Ruby implementation. They have 1.9 support and MRI extension support. The Ruby interpreter starts quickly. They support Unix features. Adding Rubinius support was pretty straightforward. The Rubinius team has done an excellent job!

Why you should use JRuby or Rubinius

JRuby and Rubinius support real multi-core concurrency. JRuby and Rubinius threads map to real OS threads, and neither Ruby implementations have a global interpreter lock. In contrast, MRI Ruby 1.8 uses userspace threading and so cannot take advantage of multi-core using a single process. MRI Ruby 1.9 has real OS threads, but also has a global interpreter lock and so still cannot take advantage of multi-core using a single process.

Granted, the multi-core issue isn’t that big. Phusion Passenger spawns multiple processes in order to take advantage of multi-core. But if you’re in a position in which you can only use 1 process, for whatever reason, then JRuby and Rubinius are what you need. With Phusion Passenger Enterprise’s multithreading support, you can have hybrid multi-processed and multi-threaded applications – the best of both worlds.

JRuby and Rubinius also often have superior performance. Both implementations support JIT compilation, which MRI Ruby does not.

That said, MRI Ruby still has the best compatibility in the Ruby ecosystem, so JRuby and Rubinius are not silver bullets. You should use the best tool for the best job. With Phusion Passenger 4’s support for multiple Ruby versions, this should be a breeze.

Where to get Phusion Passenger with JRuby/Rubinius support

JRuby/Rubinius support will become part of the upcoming 4.0.0 beta 2. Please stay tuned!

These Phusion Passenger 4 updates are just the beginning. We have more exciting changes planned for the near future! Curious? Enter your email address and name below and we’ll keep you up to date.