John Hawthorn

You're telling me a duck typed this code?

We released Ruby 4.0.9, 3.4.12, and 3.3.13, and published an announcement about Regexp compilation fixes. www.ruby-lang.org/en/news/2026... If your application compiles a regular expression from an untrusted string, please update your Ruby to one of those versions.

Ruby's GC and ZJIT got a new collab! We recently introduced inlining of the garbage collector's fastpath into ZJIT. Read more about it here: railsatscale.com/2026-09-01-z...

Feeling on top of the world after a successful #Vancouver event.

I'll be speaking at XO Ruby Vancouver on August 15th www.xoruby.com/event/vancou...

I've added the WPBL to faceoff.now - faceoff.now/wpbl

Upgrade Rails immediately, kids, this is a big one. github.com/rails/rails/...

Ruby 4.0.6 Released www.ruby-lang.org/en/news/2026... This is a routine update that includes bugfixes. We recommend upgrading your Ruby version at your earliest convenience.

> i'm going to become rich and famous after i invent a device that allows you to stab Claude Opus 4.8 in the face over the internet

If you haven't upgraded yet, Ruby 4.0's garbage collection is generally much faster than 3.4. This patch release fixes the one area there had previously been a notable regression (allocating/freeing Classes).

Ruby 4.0.4 Released www.ruby-lang.org/en/news/2026... This is a routine update that includes bugfixes. We recommend upgrading your Ruby version at your earliest convenience.

Made a new blurg post about AI + OSS security. I was going to just complain on here, but I figured a short blog post would be better for my complaining 😂 tenderlovemaking.com/2026/05/06/r...

github.com/rails/rails/...

It's just a proof of concept, but this is how I wish Rust extensions for Ruby were written: github.com/tenderworks/...

Proud of this patch I landed to Ruby this week which makes constants inside of `class << self` scopes faster both in the interpreter and JITs. It's not the most complicated or even impactful, but something I've wanted to fix for years github.com/ruby/ruby/pu...

If the catcher sees his shadow there's 6 more weeks of spring training

Ruby 4.0.2 Released www.ruby-lang.org/en/news/2026... This is a routine update that includes a bugfix in YJIT for NoMethodError on Puma. We recommend upgrading your Ruby version at your earliest convenience.

Can't wait for Sunday's game

The latest faker's version includes this improvement! Nothing like profiling your code to get some quick wins. Huge thanks to @jhawthorn.com for creating Vernier 🤓 hexdevs.com/posts/optimi...

hey folks, i’m a rails / ruby dev with a bit over 10 years of experience professionally and i was just hit with my second layoff. looking for a new role would love to chat! #rails #ruby.

Development of Ruby 4.1.0 started ``` ruby 4.1.0dev (2025-12-26T00:31:28Z master 290fa0d8b4) +YJIT +MN +PRISM [arm64-darwin25] ```

ZJIT is available starting in Ruby 4.0! Please try it out on your test suite, maybe in a staging environment, and let us know how it goes! railsatscale.com/2025-12-24-l...

One thing I'm really excited about in Ruby 4.0 is that object allocation is going to get a nice speed boost

To the uninitiated, this is what every baseball game is like.

I made it easier to search Ruby's docs www.johnhawthorn.com/2025/searchi...

I took some time to delve into my latest work on reducing Ractor contention. This time: Generic Instance Variables byroot.github.io/ruby/perform...

One of the AI generated security reports attached a bunch of MD files, and this screenshot was taken from the end of one of them. This gives me lots of feelings, and none of them are good

Ruby 3.4.5 Released www.ruby-lang.org/en/news/2025... This is a routine update that includes bug fixes and GCC 15 support. We recommend upgrading your Ruby version at your earliest convenience.

It's been a while since I've written about the innards of @compiler-explorer.com. xania.org/202506/how-c... has the details, some statistics and some fun war stories.

I just published "Implementing Embedded TypedData Objects" about a feature @byroot.bsky.social and I worked on for Ruby 3.3. A bit late, but better than never. railsatscale.com/2025-06-03-i...

I wrote a post to braindump what I'm currently working on: allowing lock-free access to class instance variables from Ractors. byroot.github.io/ruby/perform...

Ruby 3.4.4 Released www.ruby-lang.org/en/news/2025... This release includes a fix for a YJIT bug related to local variables and addresses a build issue on Windows when using GCC 15. It was released ahead of schedule to make these fixes available as soon as possible.

I did some sort of rubber duck blogging about a patch I'm currently working on: byroot.github.io/ruby/perform...

If you read @byroot.bsky.social 's "What's the deal with Ractors?", and were bummed at how poorly they handled JSON parsing, then @jhawthorn.com has brightened your day! Frozen interned strings are now stored in a lock-free hash, making the Ractor example 2x faster than the single-threaded example!

Announcing Dial, a Rails application profiler: github.com/joshuay03/dial I've longed for a free tool that provides Datadog-like profiles, with accurate GVL and GC activity. Thanks to @jhawthorn.com's amazing work on Vernier, all I needed to do was integrate it with Rails and let it do its thing.

I've just released unsafe 1.0.0! A gem bringing the power of Rust's unsafe to Ruby! github.com/jhawthorn/un...

One of my favourite things (of many) about rr-project.org is how it actually complements my tendency to be a printf debugger, because it's so easy to start gdb at the point that the output goes wrong.

andpad.connpass.com/event/346737/ registration is opened now. We welcomed oversea guest for #rubykaigi

What's new? - Quickly and easily profile your jobs in production with Vernier integration. - View multi-day job execution metrics to see performance over time. - Heavily rewritten Web UI much faster than 7.3.0. - Many more small improvements Here's Web UI 7.3 vs 8.0.

@byroot.bsky.social @bihi.bsky.social Very happy to deprecate my library thanks to all your work on JSON 🎉 github.com/jhawthorn/ra...

GitHub is now running Ruby 3.4.1

www.ruby-lang.org/en/news/2024...