RubyConf 2007 Second Day Morning

John Lam: State of IronRuby

John Lam

Photo by dwortlehock

Who works on IronRuby? The core is: John Lam, Hiabo Luo, Tomas Matousek, & John Messerly.

Why did John move from Toronto to Seattle to start working at Microsoft on IronRuby? He was in love with RubyCLR and couldn’t turn down the opportunity to work on a “real” implementation.


John wants IronRuby to be a Ruby implementation but also in changing Microsoft’s approach to opensource (“change or die”), especially the “either or approach” to thinking about opensource. However, it’s really hard to change a company that’s doing pretty well. Unfortunately, after doing some announcements about their intentions, the blogosphere decided that IronRuby was going to be the work of the devil. Today, the project is hosted on Rubyforge, has open SVN access, and has already recieved code contributions from the outside community.

Support Rails: it’s “the testbed” (dispite speculation about MS not wanting to threaten ASP.NET): it’s “the testbed” (dispite speculation about MS not wanting to threaten ASP.NET).

Run everywhere .NET runs (Mac, Linux, Windows). [John is doing the presentation on a Mac and does an irb demo (compiled on Windows) with CLR types (with nice integration between the CLR type's methods and pure Ruby methods) on Mono.]

Under the covers

[John runs the Rubinius spec suite in IronRuby in Windows on his Mac. A lot of things fail (373 failures of 1030 examples). He thanks the Rubinius team for all of their work.]

[John goes on to show a bunch of quick IronRuby demos, including some in-browser demos using IronRuby in Silverlight.] There’ll be more examples up later on his blog.

If you’re interested in making a language on .NET, please come to the Lang.NET Symposium.

Q & A

Release schedule? Unlike “real projects”, IronRuby has a “conference-driven schedule”. They want to do a push to have Rails working in IronRuby by RailsConf 2008.

Can the IronRuby developers look at other implementations source code? They have to be “extremely clean” on the DLR, but “IronRuby does not have the same restrictions” because it doesn’t ship with the OS. Explicitly, they can look at
test and test frameworks.

Charlie Nutter & Tom Enebo: JRuby: Ruby for the JVM

JRuby logo

Everyone in the audience knows already what JRuby is, so they won’t cover that. It’s a Java implementation of the Ruby 1.8 language. It’s available under a few opensource licenses, blah blah blah. They released 1.0.2 a couple of days ago (and 1.1b1 last night during Matz’ questions).

[Tim Bray fairly incomprehensively announces that Sun has done a deal with University of Tokyo to work with ? on ? and give them "a bunch of money". Another implementation?]


Installation: 1. unpack binary, 2. set PATH. Dependencies: Java 5+. jruby.jar contains the full runtime.

The lexer is a hand-written lexer ported from MRI. The parser is another port of the MIR YACC/Bison parser using Jay (Bison for Java). This parser is the key for the recent boom in IDE support for Ruby (like NetBeans). [Charlie does a little NetBeans demo showing auto-complete and variable renaming/highlighting, unused variable detection.]

The Core classes are all written in Java, and nearly all have a 1:1 correspondence (String is RubyString, Array is RubyArray, etc).

The interpreter is a “simple switch-based AST walker” that recurses for nesting. Code starts out interpreted but command-line scripts compile immediately. “eval‘d code always interpreted (for now).”

JRuby 1.1 brings full bytecode compilation. “The compiler is basically done. This is the only complete 1.8 compiler in existence.” [Charlie shows a fib benchmark. Compiling makes it quite a bit bigger in filesize (oh well). There's a _huge_ improvement when using java -server.] Typically, you want to use AOT mode, which avoids “JIT warmup time”. It may also use less memory in the future and perhaps start faster?

Charlie and Tom

Photo by dwortlehock


Performance optimizations are progressing in a few directions. The first is the obvious one of compilation. For real numbers, see this blog post. Comilation caches literals, uses Java local variables when possible, and uses “monomorphic inline method cache.” ObjectSpace is a more controversial
optimization. ObjectSpace allows you to iterate all Objects in a system. This isn’t painful in MRI, but is not easy in the fully-concurrent JRuby (“it sucks 2-5 times as much”). Charlie asserts that it is almost never used (except for Test::Unit). It’s turned off by default but can be turned on with a flag. [Some in the audience believe that the reverse should be used.] Custom implementations of Array, String, and Hash (among others) have also boosted performance.

Threading, Extensions, & Integration

JRuby supports only native OS threads but they’re parallel. They also emulate unsafe green thread operations (Thread#kill, Thread#raise, etc).

Ruby native (C) extensions are not supported. Some libraries may be accessible with JNA. If you’re looking for a good binding, consider a Java equivalent to the C. Most of the extensions that Rails uses have already been ported to Java/JRuby.

You can call Ruby from Java, you can call Java from Ruby. A popular integration is building GUIs with Swing. Ruby makes “Swing development fun” and is much less verbose than the Java version. Swing integration also brings a cross-platform GUI solution to Ruby (essentially for the first time). A direct approch:

$ jirb
>> include Java
=> Object
>> import javax.swing.JFrame
>> frame ="Hello")
=> nil
# there is a frame on the screen
>> frame.set_size(500, 500)
=> nil 

Profligacy adds a new layout language to simply GUI creation. MonkeyBars takes a GUI editor approach.


Rails works with JRuby. It uses a JDBC connector to ActiveRecord. It can generate .war files (via Warble). ActiveHibernate is coming soon, and provides a different persistence API. Ruvlets brings Servlets to JRuby.


You can use Test::Unit or RSpec for Java code. “It’s so much less code” that writing tests for Java directly.


  • JRuby is ready
  • JRuby is more than just an implementation
  • JRuby needs your help

Evan Phoenix: Rubinius 1.0

Rubinius logo src="" />

Rubinius, like IronRuby and JRuby is aiming to bring “total world domination …. for Ruby!” It’s a Smalltalk-inspired VM:

class Rubinius < Smalltalk
  # form
  include Ruby::Syntax
  # function
  include Ruby::Behavior
  include"crazy cs papers")

Rubinius debuted last year at RubyConf 2006. There’s been “enormous progress” over the course of the year.

A comparison of implementation langagues (slightly misleading):

84,516 lines of C
     0 lines of Ruby

128,786 lines of C
     50 lines of Ruby

 48,282 of C#
      0 lines of Ruby

113,508 lines of Java
  1,000 lines of Ruby

 25,398 lines of C
 13,946 lines of Ruby 

Evan Phoenix

Photo by dwortlehock

Some “Junior High Analysis”:

  • 1.8 & 1.9 is Ruby (core) for C programmers
  • JRuby is Ruby for Java programmers
  • IronRuby is Ruby for C# programmers
  • Rubinius is Ruby for Ruby programmers

Rubinius finally allows Ruby programmers to “eat yummy dogfood.” It’s targeted at fellow Ruby programmers, not folks on the street. It also provides a much tighter feedback loop for language improvements & clarification.

Following on that, they have 57 committers, with 17 of those with 20 or more commits (36 with 100+ lines changed). Commit bits have been “free flowing” and easy to get (if something you submit as a patch you get commit rights).

Props to EngineYard for funding Evan’s work on Rubinius.

Evan is shooting to have 1.0 out by ? (was: RubyConf 2007). Things change. Mistakes were made. They’re evolving.

Q & A

Given the fact that Ola Bini and Avi Bryant should Rubinius replace MRI eventually? The chicken didn’t decide to replace the dinosaur [laughs], the environment did. The ultimate goal (from the start) wasn’t “replace MRI”, it was “total world domination”.

Are you more interested in performance than conformance? Rubinius has some compiler flags to turn certain optimizations on and off.

How small do you think you can get the C? They’ll follow Squeak in that they’ll write a C generator. The final goal is hand-maintained lines of C==0.

Are you worried about incompatibilities? We’re all worried about that. We wouldn’t checking something that intentionally broke compatibility.

What are these specs you’re writing? Do you pass them? They’re as implementation-agnostic as possible and written for MiniRSpec
(intended to sytnax-compatible with RSpec). Compatibility is all centered on emulating MRI. We used to fail ~1100 specs a few weeks ago, today we’re closer to ~500. The improvement is all due to community involvement.

Have you made any enhancements? Yeah, we did some prettier backtraces andcapturing exceptions from C extension segfaults, for example.

Is Rubinius challenged by ObjectSpace, Continuations, &Selector Namespaces? They have a problem with ObjectSpace like JRuby, continuations are “our shiny awesomeness” (thanks Smalltalk’s spaghetti stack) [shows continuation demo], and (no comment on SN).

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