JRuby RC2 Released; What's Next?

Today, Tom got the JRuby 1.1 RC2 release out. It's an astounding collection of performance improvements and compatibility fixes. Here's Tom's JRuby 1.1 RC2 announcement.

Let's recap a little bit:
  • There have been additional performance improvements in RC2 over RC1. Long story short, performance of most trivial numeric benchmarks approaches or exceeds Ruby 1.9, while most others are on par. So in general, we have started using Ruby 1.9 performance as our baseline.
  • Unusual for an RC cycle are the 260 bugs we fixed since RC1. Yes, we're bending the rules of RCs a bit, but if we can fix that many bugs in just over a month, who can really fault us for doing so? Nobody can question that JRuby is more compatible with Ruby 1.8.6 than any other Ruby implementation available.
  • We've also included a number of memory use improvements that should reduce the overall memory usage of a JRuby instance and perhaps more importantly reduce the memory cost of JIT compiled code (so called "Perm Gen" space used by Ruby code that's been compiled to JVM bytecode). In quick measurements, an application running N instance of JRuby used roughly 1/Nth as much perm gen space.
So there's really two big messages that come along with this release. The first is that JRuby is rapidly becoming the Ruby implementation of choice if you want to make a large application as fast and as scalable as possible. The thousands of hours of time we've poured into compatibility, stability, and performance are really paying off. The second message comes from me to you:

If you haven't looked at JRuby, now's the time to do so.

All the raw materials are falling into place. JRuby is ready to be used and abused, and we're ready to take it to the next level for whatever kinds of applications you want to throw at it. And not only are we ready, it's our top priority for JRuby. We want to make JRuby work for you.

And that brings me to the "What's Next" portion of this post. Where do we go from here?

We've got a window for additional improvements and fixes before 1.1 final. That much is certain, and we want to fill that time with everything necessary to make JRuby 1.1 a success. So we need your help...find bugs, file reports, let us know about performance bottlenecks. And if you're able, help us field those reports by fixing issues and contributing patches.

But we also have a unique opportunity here. JRuby offers features not found in any other Ruby implementation, features we've only begun to utilize:

Inside a single JVM process, JRuby can be used to host any number of applications, scaling them to any number of concurrent users.

This one applies equally well to Rails and to other web frameworks rapidly gaining popularity like Merb. And new projects like the GlassFish gem are leading the way to simple, scalable, no-hassle hosting for Ruby web applications. But we're pretty resource-limited on the JRuby project. We've got two full-time committers and a handful of part-timers and after-hours contributors pouring their free time into helping out. For JRuby web app hosting to improve and meet your requirements, we're going to need your use cases, your experience, and your input. We're attempting to build the most scalable, best-performing Ruby web platform with JRuby, but we're doing it in true OSS style. No secrets, no hidden agendas. This is going to be your web platform, or our efforts are wasted. So what should it look like?

The GlassFish gem is the first step. It leverages some of the best features of the Java platform: high-speed asynchronous IO, native threading, built-in management and monitoring, and application namespace isolation (yes, even classloaders have a good side) to make Ruby web applications a push-button affair to deploy and scale. With one command, your app is production-ready. No mongrel packs to manage, no cluster of apps to monitor, and no WAR file relics to slow you down. "glassfish_rails myapp" and you're done; it's true one-step deployment. Unfortunately right now it only supports Rails. We want to make it not only a rock-solid and high-performance Rails server, but also a general-purpose "mod_ruby" for all Ruby web-development purposes. It's the right platform at the right time, and we're ready to take it to the next level. But we need you to try it out and let us know what it needs.

JRuby's performance regularly exceeds Ruby 1.8.6, and in many cases has started to exceed Ruby 1.9.

At this point I'm convinced JRuby will be able to claim the title of "fastest Ruby implementation", for some definition of "Ruby". And if we're not there yet, we will be soon. With most benchmarks meeting or exceeding Ruby 1.8.6 and many approaching or exceeding Ruby 1.9 we're feeling pretty good. What I've learned is that performance is important, but it's not the driving concern for most Ruby developers, especially those building web applications usually bounded by unrelated bottlenecks in IO or database access. But that's only what I've been able to gather from conversations with a few of you. Is there more we need to do? Should we keep going on performance, or are there other areas we should focus on? Do you have cases where JRuby's performance doesn't meet your needs?

JRuby performance future is largely an open question right now. A stock JRuby install performs really well, "better enough" that many folks are using it for performance-sensitive apps already. We know there's bottlenecks, but we've solving them as they come up, and we're on the downward slope. Outside of bottlenecks, do we have room to grow? You bet we do. I've got prototype and "experimental" features already implemented and yet to be explored that will improve JRuby's performance even more. Of course there's always tradeoffs. You might have to accept a larger memory footprint, or you may have to turn off some edge-case features of Ruby that incur automatic performance handicaps. And some of the wildest improvements will depend on dynamic invocation support (hopefully in JDK 7) and a host of other features (almost certain to be available in the OpenJDK "Multi-language VM" subproject). But where performance improvements are needed, they're going to happen, and if I have any say they're going to happen in such a way that all other JVM languages can benefit as well. I'm looking to you folks to help us prioritize performance and point us in the right direction for your needs.

JRuby makes the JVM and the Java platform really shine, with excellent language performance and a "friendlier" face on top of all those libraries and all that JVM magic.

I think this is an area we've only just started to realize. Because JRuby is hosted on the JVM, we have access to the best JIT technology, the best GC technology, and the best collection of libraries ever combined into a single platform. Say what you will about Java. You may love the language or you may hate it...but it's becoming more and more obvious that the JVM is about a lot more than Java. JRuby is, to my knowledge, the only time a non-JVM language has been ported to the JVM and used for real-world, production deployments of a framework never designed with the JVM in mind. We've taken an unspecified single-implementation language (Matz's Ruby) and its key application framework, (Rails) and delivered a hosting and deployment option that at least parallels the original and in many ways exceeds it. And this is only the first such case...the Jython guys now have Django working, and it's only a matter of time before Jython becomes a real-world usable platform for Python web development. And there's already work being done to make Merb--a framework inspired by Rails but without many of Rails' warts--run perfectly in JRuby. And it's all open source, from the JVM up. This is your future to create.

I think the next phase for JRuby will bring tighter, cleaner integration with the rest of the Java platform. Already you can call any Java-based library as though it were just another piece of Ruby code. But it's not as seamless as we'd like. Some issues, like choosing the right target method or coercing types appropriately, are issues all dynamic languages face calling into static-typed code. Groovy has various features we're likely to copy, features like explicit casting and coercing of types and limited static type declaration at the edges. Frameworks like the DLR from Microsoft have a similar approach, since they've been designed to make new languages "first class" from day one. We will work to find ways to solve these sorts of problems for all JVM languages at the same time we solve them for JRuby. But there's also a lot that needs to come from Ruby users. What can we do to make the JVM and all those libraries work for you?

I guess there's a simple bottom line to all this. JRuby is an OSS project driven mostly by community contributors (5 out of 8 committers working in their free time and hundreds of others contributing patches and bug reports), based on an OSS platform (not only OpenJDK, but a culture of Free software and open source that permeates the entire Java ecosystem), hosting OSS frameworks and libraries (Rails, Merb, and the host of other apps in the Ruby world). All this is meaningless without you and your applications. We're ready to pour our effort into making this platform work for you. Are you ready to help us?
Written on February 17, 2008