JRuby has, for some time now, run the same test suite as MRI (C Ruby, Matz's Ruby). Because not all tests pass, we use minitest-excludes to mask out the failures, and over time we unmask stuff as we fix it.
However, there's a number of warnings we get from the...

While at GoGaRuCo this weekend, I finally made good on an experiment I had been thinking about for a while: a static compiler for Ruby. I thought I'd share it with you good people today.
First we have a simple Ruby script with a class in it:...

I had an interesting realization tonight: I'm terrified of hash tables. Specifically, my work on JRuby (and even more directly, my work optimizing JRuby) has made me terrified to ever consider using a hash table in the hot path of any program or piece of code if there's any possibility...

This was originally posted as a comment on @fogus's blog post "Why Clojure doesn’t need invokedynamic, but it might be nice". I figured it's worth a top-level post here.
Ok, there's some good points here and a few misguided/misinformed positions. I'll try to cover everything...

This is the first of a set (not a series...there's no particular order) of articles I'll write on how JRuby is using invokedynamic. Hopefully they will show Rubyists how drastically invokedynamic is going to improve JRuby, and show other JVM language folks how to use invokedynamic effectively.
Hello friends!...

Java 7 has landed, with a modest set of new features and a few major improvements as well. What can you expect from JRuby running on Java 7?
What's In Java 7The biggest changes in Java 7 are not related to the Java language at all. Sure, there's the "project...

So after months of not blogging anything technical, I'm going to blog something non-technical. Hopefully tech posts will pick up soon once my new baby boy Elliott is a bit older and less needy :)
When Is "This Friday"?...

Android is really an amazing little platform, but occasionally you will run into API differences. Some of these are actual bugs (like a number of reflection and enum issues in early releases), and others are just weakly-specified APIs.
Today, I worked on JRUBY-5541: Problem with java_import on Android (Ruboto)...

You may have seen recently that Java suffers from a similar floating-point parsing bug to the one that recently affected PHP users. The basic gist of it is that for this special 64-bit floating point value, the Java call Double.parseDouble("2.2250738585072012e-308") will get stuck in an infinite loop. Read the link...

Amazon this week announced Elastic Beanstalk, a managed Apache Tomcat service for AWS. Naturally, I had to try JRuby on it.
First, the bad:AWSEB is really slow to deploy stuff. Several times it got "stuck" and I waited for more than 30 minutes for it to recover. It did not...

JRuby is an implementation of Ruby, and in order to achieve the high level of compatibility we boast we've had to put in some extra work. Probably the biggest area is in management of String data.
Strings in Ruby 1.8...

Sometimes it's the little things that make all the difference in the world.
For a long time, we've extolled the virtues of the amazing JVM tool ecosystem. There's literally dozens of profiling, debugging, and monitoring tools, making JRuby perhaps the best Ruby tool ecosystem you can get. But there's a...

Another present for you JRubyists out there!
JRuby has had notoriously bad startup times. Not as bad as, say, IronRuby (sorry guys!), but definitely a big fat hit every time you need to run some Ruby code from the command line. Some of this overhead was related to JRuby, and...

This should be a great Christmas present for many of you.
After over three years, the "ruby-debug" gem finally installs properly on JRuby...

This was going to be a reply to a friend on Twitter, when I realized it would be several tweets and I might as well put them in one place.
Grant Michaels (@grantmichaels) sent me this link to the October JCP (Java Community Process) EC (Expert Committee) meeting notes. The...

(This is a repost of an article I wrote in 2004, which I stumbled upon this evening and thought worthy of a reprint. Feel free to rip it up and offer your own commentary. I think it is still 100% valid.)
I came up with the most compelling idea for...

As you've probably heard by now, Oracle has decided to file suit against Google, claiming multiple counts of infringement against Java or JVM patents and copyrights they acquired when they assimilated Sun Microsystems this past year. Since I'm unlikely to keep my mouth shut about even trivial matters, something this...

As part of the Ruby Summer of Code, Tim Felgentreff has been building out C extension support for JRuby. He's already made great progress, with simple libraries like Thin and Mongrel working now and larger libraries like RMagick and Yajl starting to function. And we haven't even reached the mid-term...

This is the third post in a series. The first two were on Browsing Memory the JRuby Way and Finding Leaks in Ruby Apps with Eclipse Memory Analyzer
Hello again, friends! I'm back with more exciting memory analysis tips and tricks! Ready? Here we go!...

After my post on Browsing Memory the JRuby Way, one commenter and several other folks suggested I actually show using Eclipse MAT with JRuby. So without further ado...
The Eclipse Memory Analyzer, like many Eclipse-based applications, starts up with a "for dummies" page linking to various actions...