Jean Boussier@_byroot

Rails core, Ruby committer, Senior Principal Engineer at Intercom. Bsky: byroot.bsky.social Mastodon: @byroot@ruby.social

 Toulouse
github.com/byroot
Joined April 2022
87 Photos and videos
After several months of work, we finally enabled Pitchfork reforking on 100% of Shopify's monolith. ~30% reduction in memory usage, ~9% better latency and more! railsatscale.com/2023-10-23-…

Effects of Pitchfork reforking on Shopify’s Monolith

Over the last year, I’ve been working on a new Ruby application server called Pitchfork. In most regards it’s extremely similar to the venerable Unicorn, from which it originates, but with one major...

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Jean Boussier retweeted
rubyireland@rubyireland
Aug 18
🚂 Ruby Ireland is back! Agents of Concurrency - September 10th at @fin_ai Jean Boussier makes the case for multiprocessing in Rails, while Ryan Sherlock gets into shipping AI agents on Rails - fast, repeatedly, and in production. Thx Fin! RSVP 👇 meetup.com/rubyireland/event…

Agents of Concurrency, Thu, Sep 10, 2026, 6:30 PM | Meetup

It's quite late in the year to be coming out of hibernation but if rarity makes a thing more precious then this event is surely is one heck of a valuable meetup. And indeed

meetup.com
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A quick followup on Ruby Hashes byroot.github.io/ruby/perfor…

Speeding Up (small) Ruby Hashes

Something I must confess is that I absolutely hate writing these blog posts. It’s not quite as bad as having to give a conference talk, but it’s up there on the list of activities that feel like...

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I'll probably release the final 3.0.0 version early September, so if you got time please try the RC1 and submit any feedback you may have: github.com/ruby/json/release…

Release v3.0.0.rc1 · ruby/json

With the removal of the insecure create_additions option, JSON.load and JSON.dump are now safe to use. Them being unsafe by default caused multiple security vulnerabilites in the past. If you did d...

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A history of Ruby's Hash tables, and how we can make them use less memory: byroot.github.io/ruby/perfor…

Shrinking Ruby Hashes

As you may know, one area of Ruby performance optimization that particularly interests me is memory usage. Given that most Ruby deployments rely on fork, improving Copy-on-Write performance is...

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While it has been 18 months since I blogged about it, the json gem performance has improved quite significantly since, so now is a good time to add a few more parts to my JSON series: byroot.github.io/ruby/json/2…

Optimizing Ruby’s JSON, Part 8

It has now been about 18 months since I concluded my post series on optimising Ruby’s json.

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This one feels good. No more stupid comments at the top of files. At least in one repo.
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Jean Boussier retweeted
Hiroshi SHIBATA@hsbt
Apr 20
I wrote answer letter: github.com/ruby/rubygems/dis…

Proposal: override DSL in Gemfile for managing version constraints · ruby rubygems · Discussion...

Background In the discussion around #9454, reviewers (including @byroot and @Edouard-chin) pointed out that BUNDLE_IGNORE_RUBY_UPPER_BOUNDS and BUNDLE_IGNORE_RUBYGEMS_UPPER_BOUNDS should be express...

github.com
Jean Boussier@_byroot
Apr 20
I wrote some more as a way to fight jet lag, hopefully it's still readable 😅: byroot.github.io/ruby/bundle…
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I wrote some more as a way to fight jet lag, hopefully it's still readable 😅: byroot.github.io/ruby/bundle…

The Missing Bundler Features

Over the last few months, there has been a lot of talk about making Bundler faster, both by improving it directly, or by reimplementing it in another language, and while it may surprise some, that...

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With the new job, I didn't get much time or energy to blog lately, but I figured I'd use the various downtime while traveling to Ruby Kaigi to write about some of the things I worked on recently: byroot.github.io/ruby/perfor…

Optimizing Ruby Path Methods

Back in November last year, I started a new job at Intercom, and one of the first projects I got to work on was improving the Intercom monolith CI with some of my new colleagues.

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Happy to share that today I'm starting as senior principal at Intercom!
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I was recently reminded that not everyone fully understand what the frozen string literal magic comment is about. So I figured it was the occasion for another deep dive. byroot.github.io/ruby/perfor…

Frozen String Literals: Past, Present, Future?

If you are a Rubyist, you’ve likely been writing # frozen_string_literal: true at the top of most of your Ruby source code files, or at the very least, that you’ve seen it in some other projects.

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I tried to explain why I don't believe the recent accusations toward my former teammates, as well as how the Ruby and Rails Infra team at Shopify operates and why it can be trusted. byroot.github.io/opensource/…

Dear Rubyists: Shopify Isn’t Your Enemy

I’ve been meaning to write a post about my perspective on Open Source and corporate entities. I already got the rough outline of it; however, I’m suffering from writer’s block, but more importantly,...

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Jean Boussier retweeted
Robby Russell
@robbyrussell
28 Aug 2025
Honored to be back on stage at #RailsWorld in Amsterdam next week to help guide a conversation with @tenderlove, @_byroot, and @hsbt. Still a few days before I lock in the topics. What questions would you love to hear them answer?
Ruby on Rails
@rails
26 Aug 2025
Members of the Rails Core and Ruby committer teams come together for a special session on the #RailsWorld stage next week. @tenderlove, @_byroot, and @hsbt will chat with host @robbyrussell about the future of DevEx in the Ruby and Rails ecosystem, and how foundational tools like RubyGems, Bundler, RDoc, Debug, and ERB can be improved to make the language and framework more welcoming. rubyonrails.org/world/2025/d…
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I took some time to delve into my latest work on reducing Ractor contention. This time: Generic Instance Variables byroot.github.io/ruby/perfor…

Unlocking Ractors: generic instance variables

In two previous posts, I explained that one of the big blockers for Ractors’ viability is that while they’re supposed to run fully in parallel, in many cases, they’d perform worse than a single...

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Bio update: s/Senior Staff Engineer on Shopify's Ruby and Rails infrastructure team/ funemployed/ After almost 12 years, today was my last day at the company. 🫡
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Beyond performance work, I deprecated a bunch of APIs in the JSON gem, and added others, so I figured it would be a good occasion to talk about API design: byroot.github.io/ruby/json/2…

What’s wrong with the JSON gem API?

As I mentioned at the start of my Optimizing Ruby’s JSON series of posts, performance isn’t why I candidated to be the new gem’s maintainer.

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Jean Boussier retweeted
Peter Zhu@peterzhu2118
3 Jun 2025
I just published "Implementing Embedded TypedData Objects" about a feature @_byroot and I worked on for Ruby 3.3. A bit late, but better than never. railsatscale.com/2025-06-03-…

Implementing Embedded TypedData Objects

We implemented a new feature to TypedData objects in Ruby, called embedded TypedData objects. TypedData objects are used across a wide variety of Ruby types, such as Time, Enumerator, and Method....

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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/perfor…

Unlocking Ractors: class instance variables

In a previous post about ractors, I explained why I think it’s really unlikely you’d ever be able to run an entire application inside a ractor, but that they could still be situationally very useful...

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

Unlocking Ractors: object_id

In a previous post about ractors, I explained why I think it’s really unlikely you’d ever be able to run an entire application inside a ractor, but that they could still be situationally very useful...

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Some personal thoughts on the usability of MySQL and PostgreSQL protocols: byroot.github.io/performance…

Database Protocols Are Underwhelming

If you’ve been in this trade for a while, you have probably seen dozens of debates on the merits and problems of SQL as a relational database query language. As an ORM maintainer, I have a few gripes...

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