Charles Oliver Nutter
@headius.bsky.social
JRuby co-lead, Java champion, Ruby hero, JavaOne Rockstar, international traveler and speaker. Book me for your next event! I depend on your donations and sponsorships! https://github.com/sponsors/headius
It's incredible the amount of hacking required to get Rails to run in parallel with Ractors (and it still isn't there yet) when JRuby has been running Rails in parallel for decades. #railsworld
September 23, 2026 at 4:54 PM
It's incredible the amount of hacking required to get Rails to run in parallel with Ractors (and it still isn't there yet) when JRuby has been running Rails in parallel for decades. #railsworld
Reposted by Charles Oliver Nutter
Hello JRubyists! Anyone planning to be at tiny ruby #{conf} 2026 presented by @helsinkiruby.fi next week? We'd love to help you spread the word about JRuby to the Helsinki Ruby community! Get in touch if we can help you in any way!
September 21, 2026 at 5:56 PM
Hello JRubyists! Anyone planning to be at tiny ruby #{conf} 2026 presented by @helsinkiruby.fi next week? We'd love to help you spread the word about JRuby to the Helsinki Ruby community! Get in touch if we can help you in any way!
It occurs to me now: with the JVM now supporting native function calls and memory via the FFM API, could we not potentially treat it as a C compiler backend?
September 20, 2026 at 2:11 AM
It occurs to me now: with the JVM now supporting native function calls and memory via the FFM API, could we not potentially treat it as a C compiler backend?
Would you buy JRuby swag to help fund the project? We recently did a run of JRuby "bird" t-shirts that have been very popular, but that stuff is expensive to give away for a little startup like ours.
September 20, 2026 at 2:09 AM
Would you buy JRuby swag to help fund the project? We recently did a run of JRuby "bird" t-shirts that have been very popular, but that stuff is expensive to give away for a little startup like ours.
Brno is a lovely little city. Don't know why I didn't see it when I visited in 2012.
September 19, 2026 at 12:14 PM
Brno is a lovely little city. Don't know why I didn't see it when I visited in 2012.
It's amazing how quickly the toxic AI bros come out on X if you say one bad word about AI. Are they even real people?
September 18, 2026 at 7:54 PM
It's amazing how quickly the toxic AI bros come out on X if you say one bad word about AI. Are they even real people?
I think I'm going to enable the JVM vector API (SSE etc, we already ship some optimizations that use it) by default for JRuby. Convince me not to.
September 18, 2026 at 6:45 PM
I think I'm going to enable the JVM vector API (SSE etc, we already ship some optimizations that use it) by default for JRuby. Convince me not to.
After all these years, I just got burned (almost) by having a CI job not actually fail when one of the steps failed. It involved a subprocess launch with no error check, so even if it bombed out the job stayed green. 😩
A friendly reminder to make sure your CI jobs actually *can* fail.
A friendly reminder to make sure your CI jobs actually *can* fail.
September 18, 2026 at 5:34 PM
After all these years, I just got burned (almost) by having a CI job not actually fail when one of the steps failed. It involved a subprocess launch with no error check, so even if it bombed out the job stayed green. 😩
A friendly reminder to make sure your CI jobs actually *can* fail.
A friendly reminder to make sure your CI jobs actually *can* fail.
Slides from my Euruko 2026 talk "JRuby: Past, Present, and Future" are now uploaded. I believe the talks were also recorded, so hopefully video will follow soon. Great event, I hope to return for 2027 in Modena, Italy!
buff.ly/paSd5t9
buff.ly/paSd5t9
JRuby: Past, Present, and Future
JRuby on Rails is 20 years old! This talk reviews the last 20 years of JRuby development, with a focus on the challenges of supporting Ruby and Rails ye…
buff.ly
September 18, 2026 at 5:03 PM
Slides from my Euruko 2026 talk "JRuby: Past, Present, and Future" are now uploaded. I believe the talks were also recorded, so hopefully video will follow soon. Great event, I hope to return for 2027 in Modena, Italy!
buff.ly/paSd5t9
buff.ly/paSd5t9
AI is now the largest single point of failure in the history of software development. I know tons of developers that can't even work without an agent now. It's shocking how quickly the industry has become totally dependent on a few companies' services.
September 18, 2026 at 4:15 PM
AI is now the largest single point of failure in the history of software development. I know tons of developers that can't even work without an agent now. It's shocking how quickly the industry has become totally dependent on a few companies' services.
I'm finding more and more that agent-driven developers *really* appreciate having a human validate what they submit. nobody wants to be the asshole in an OSS project and being honest and communicative goes a long way toward making a good patch.
September 18, 2026 at 3:01 PM
I'm finding more and more that agent-driven developers *really* appreciate having a human validate what they submit. nobody wants to be the asshole in an OSS project and being honest and communicative goes a long way toward making a good patch.
Like clockwork, I go to a Ruby event and meet JRuby users I never knew about! Just today, three people who used JRuby at previous jobs and two more that currently have apps in production. Gotta figure out how to reach these folks without speaking at every Ruby conference! 🤣
September 17, 2026 at 4:23 PM
Like clockwork, I go to a Ruby event and meet JRuby users I never knew about! Just today, three people who used JRuby at previous jobs and two more that currently have apps in production. Gotta figure out how to reach these folks without speaking at every Ruby conference! 🤣
Interested in Ruby::Box? Use JRuby and you already have it! These are fully-isolated, fully-parallel JRuby VMs running in the same process. Here's a simple example from my Euruko 2026 talk. Let's work together to make Box work on ALL Rubies!
September 17, 2026 at 11:25 AM
Interested in Ruby::Box? Use JRuby and you already have it! These are fully-isolated, fully-parallel JRuby VMs running in the same process. Here's a simple example from my Euruko 2026 talk. Let's work together to make Box work on ALL Rubies!
Feels nice to be back in Czechia! I'm currently transiting from Prague to Brno for Euruko 2026. I think the last time I visited was almost 14 years ago, shortly after first joining Red Hat. I have a free day before and after the conference so I'm hoping to do a bit of touring.
September 15, 2026 at 9:10 AM
Feels nice to be back in Czechia! I'm currently transiting from Prague to Brno for Euruko 2026. I think the last time I visited was almost 14 years ago, shortly after first joining Red Hat. I have a free day before and after the conference so I'm hoping to do a bit of touring.
My own experiments using AI for JRuby work have been mixed, but I can report a great success: contributions from people that never would have attempted such things before, like Ruby core devs and Rubyists with no JVM experience. So many PRs lately! github.com/jruby/jruby
GitHub · Change is constant. GitHub keeps you ahead.
Join the world's most widely adopted, AI-powered developer platform where millions of developers, businesses, and the largest open source community build software that advances humanity.
github.com
September 14, 2026 at 7:16 PM
My own experiments using AI for JRuby work have been mixed, but I can report a great success: contributions from people that never would have attempted such things before, like Ruby core devs and Rubyists with no JVM experience. So many PRs lately! github.com/jruby/jruby
Reposted by Charles Oliver Nutter
Last call: EuRuKo 2026 tickets close tomorrow at midnight CEST.
@matz.bsky.social opening, @ko1s.bsky.social closing, @headius.bsky.social on JRuby. Brno, Sept 17–18.
After tomorrow there's no late registration.
2026.euruko.org
@matz.bsky.social opening, @ko1s.bsky.social closing, @headius.bsky.social on JRuby. Brno, Sept 17–18.
After tomorrow there's no late registration.
2026.euruko.org
September 13, 2026 at 8:38 AM
Last call: EuRuKo 2026 tickets close tomorrow at midnight CEST.
@matz.bsky.social opening, @ko1s.bsky.social closing, @headius.bsky.social on JRuby. Brno, Sept 17–18.
After tomorrow there's no late registration.
2026.euruko.org
@matz.bsky.social opening, @ko1s.bsky.social closing, @headius.bsky.social on JRuby. Brno, Sept 17–18.
After tomorrow there's no late registration.
2026.euruko.org
I recently had a nice chat on the Technology for Humans podcast about the past, present and future of JRuby... including some myth debunking that might help Ruby folks look past the "J" to the amazing tech underneath. Check out the video here:
www.youtube.com/watch?v=Q9Sq...
www.youtube.com/watch?v=Q9Sq...
The Ruby Runtime Built for Scale, Parallelism and Enterprise : JRuby
YouTube video by Technology For Humans
www.youtube.com
September 2, 2026 at 7:38 PM
I recently had a nice chat on the Technology for Humans podcast about the past, present and future of JRuby... including some myth debunking that might help Ruby folks look past the "J" to the amazing tech underneath. Check out the video here:
www.youtube.com/watch?v=Q9Sq...
www.youtube.com/watch?v=Q9Sq...
And thanks to JRuby friend @cglee.bsky.social I now also have a ticket! Super excited to join the hallway track and show folks how to do more with Rails using JRuby! 🤩
Good news! I will be in Austin during Rails World 2026 and available for JRuby office hours. I'm still looking for a ticket (budget is very tight!) but I can't miss out on meeting Rails folks from around the world. If you're a JRuby user or might like to be, let's grab a drink and chat!
September 2, 2026 at 6:36 PM
And thanks to JRuby friend @cglee.bsky.social I now also have a ticket! Super excited to join the hallway track and show folks how to do more with Rails using JRuby! 🤩
Good news! I will be in Austin during Rails World 2026 and available for JRuby office hours. I'm still looking for a ticket (budget is very tight!) but I can't miss out on meeting Rails folks from around the world. If you're a JRuby user or might like to be, let's grab a drink and chat!
September 1, 2026 at 6:57 PM
Good news! I will be in Austin during Rails World 2026 and available for JRuby office hours. I'm still looking for a ticket (budget is very tight!) but I can't miss out on meeting Rails folks from around the world. If you're a JRuby user or might like to be, let's grab a drink and chat!
Friendly reminder to JRuby users out there: JRuby dev is now funded almost exclusively by support services from headius.com/services, delivering priority bug fixes, security SLAs, codebase and performance help under NDA, and much more. Sign up today or ping me for more info... and tell your friends!
JRuby Support Services
Enterprise JRuby support, consulting, and priority bug-fixing from the core developers who built it. 20+ years of JVM and Ruby expertise.
headius.com
August 13, 2026 at 3:00 PM
Friendly reminder to JRuby users out there: JRuby dev is now funded almost exclusively by support services from headius.com/services, delivering priority bug fixes, security SLAs, codebase and performance help under NDA, and much more. Sign up today or ping me for more info... and tell your friends!
My experiments with agent-augmented dev feel like "coding by dictation", and always require manual review and MANY follow-ups.
Code style: terrible.
Naming things: terrible.
Math: terrible.
Forward-thinking design: terrible.
Unsure if I'm more productive or less. 🫤
Code style: terrible.
Naming things: terrible.
Math: terrible.
Forward-thinking design: terrible.
Unsure if I'm more productive or less. 🫤
August 7, 2026 at 9:20 PM
My experiments with agent-augmented dev feel like "coding by dictation", and always require manual review and MANY follow-ups.
Code style: terrible.
Naming things: terrible.
Math: terrible.
Forward-thinking design: terrible.
Unsure if I'm more productive or less. 🫤
Code style: terrible.
Naming things: terrible.
Math: terrible.
Forward-thinking design: terrible.
Unsure if I'm more productive or less. 🫤
Reposted by Charles Oliver Nutter
💎 20 years of JRuby. @headius.bsky.social joins EuRuKo 2026 in Brno to cover JRuby's past, present & what's next.
Sep 17-18, Brno.
Tickets: 2026.euruko.org
Sep 17-18, Brno.
Tickets: 2026.euruko.org
August 6, 2026 at 2:47 PM
💎 20 years of JRuby. @headius.bsky.social joins EuRuKo 2026 in Brno to cover JRuby's past, present & what's next.
Sep 17-18, Brno.
Tickets: 2026.euruko.org
Sep 17-18, Brno.
Tickets: 2026.euruko.org
I occasionally want to close an experimental PR without losing the context and changes associated with it. Is there a better way than dumping a patch into comments as seen below? I don't want lingering topic branches.
github.com/jruby/jruby/...
github.com/jruby/jruby/...
Allow binding instance/internal vars to fields by headius · Pull Request #8804 · jruby/jruby
This is an extension of the existing mechanism for reification of Ruby classes, allowing us to use normal Java fields for either instance or internal variables. The logic here is largely unchanged ...
github.com
July 27, 2026 at 7:38 PM
I occasionally want to close an experimental PR without losing the context and changes associated with it. Is there a better way than dumping a patch into comments as seen below? I don't want lingering topic branches.
github.com/jruby/jruby/...
github.com/jruby/jruby/...
Reposted by Charles Oliver Nutter
JRuby 10.1.1.0 is released, with a bunch of compat fixes, more performance work, and several third-party CVEs resolved. JRuby 10.1 is our active development branch, with 10.0 being stable. Upgrading is recommended if you want the latest and greatest!
www.jruby.org/2026/07/22/j...
www.jruby.org/2026/07/22/j...
JRuby 10.1.1.0 Released — JRuby.org
The JRuby community is pleased to announce the release of JRuby 10.1.1.0.
www.jruby.org
July 22, 2026 at 6:33 PM
JRuby 10.1.1.0 is released, with a bunch of compat fixes, more performance work, and several third-party CVEs resolved. JRuby 10.1 is our active development branch, with 10.0 being stable. Upgrading is recommended if you want the latest and greatest!
www.jruby.org/2026/07/22/j...
www.jruby.org/2026/07/22/j...
Is there any standard in place for marking content with its level of AI contribution? Basically, a *standard* way to mark your content as fully human generated all the way up to fully AI generated. Doesn't seem like there's a good standard.
July 23, 2026 at 5:31 AM
Is there any standard in place for marking content with its level of AI contribution? Basically, a *standard* way to mark your content as fully human generated all the way up to fully AI generated. Doesn't seem like there's a good standard.