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Joshua Young

@joshuay03

Senior Software Engineer at Buildkite, Rubyist, Rails Issues team member, Puma and Concurrent Ruby maintainer, RubyGems on-call volunteer, and OSS contributor.

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03.11.2024
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Latest posts by Joshua Young @joshuay03

Congrats! See you there!

17.02.2026 20:40 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
Release v1.3.6 Β· ruby-concurrency/concurrent-ruby What's Changed Run tests without the C extension in CI by @eregon in #1081 Fix typo in Promise docs by @danieldiekmeier in #1083 Correct word in readme by @wwahammy in #1084 Fix mistakes in MVar d...

concurrent-ruby 1.3.6 is released: github.com/ruby-concurr...
It automatically prunes unused threads of a thread pool even when no new work is queued, migrates away from the deprecated "non-typed data" C API and includes several bug fixes.

13.12.2025 12:53 πŸ‘ 5 πŸ” 1 πŸ’¬ 0 πŸ“Œ 0
Screenshot of a terminal demonstrating object allocation speedup. Ruby 4.0 is about 2x faster

Screenshot of a terminal demonstrating object allocation speedup. Ruby 4.0 is about 2x faster

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

13.12.2025 20:09 πŸ‘ 89 πŸ” 10 πŸ’¬ 3 πŸ“Œ 0

Awesome stuff! πŸ™ŒπŸ½

12.11.2025 07:05 πŸ‘ 3 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

Congrats! πŸ™ŒπŸ½

11.11.2025 11:03 πŸ‘ 2 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

One last thing I should mention. This doesn't require that your app be ractor safe. The goal is to offload suitable work (just one task for now, I have ideas for at least one more) within the web server itself to ractors, so you can benefit from them without any changes to your app.

5/5

10.11.2025 17:43 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

I also need to stop posting stuff like this when it's late for me πŸ˜… I'll come back to answer any questions in the morning. I don't want to divulge too much, especially cause there's a lot more testing I need to do, which could result in major changes before I make it public πŸ€·πŸ½β€β™‚οΈ

4/5

10.11.2025 17:43 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

While being inspired by it, I'm making a few design decisions different to Puma that seem to be working out. I won't go into detail yet, but I'll document them eventually. The obvious one is utilising ractors (I'm sure you could guess what for), which Puma should probably also do at some point.

3/5

10.11.2025 17:43 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

Soooo many disclaimers:
- not a 1:1 comparison, just as close as I could get it for a benchmark baseline
- not a competition, just showing off an exciting experimental working PoC
- just a micro (but not trivial) benchmark using a toy app
- the RHS isn't 100% rack compliant, maybe 60ish%
- etc.

2/5

10.11.2025 17:43 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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I really shouldn't be sharing teasers given how much work's left to do, and the good chance that this becomes another forgotten experiment, but I'm pretty happy with how far I got with barely any tuning (compared to the 20-year battle-tested Puma, which I've taken some inspiration from <3).

1/5

10.11.2025 17:43 πŸ‘ 4 πŸ” 1 πŸ’¬ 1 πŸ“Œ 0

Thank you!

07.11.2025 01:47 πŸ‘ 5 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
Preview
ractor-shim/lib/ractor/shim.rb at 69d4d568fdac3f212de3e7d7c3133f31564dc4ec Β· eregon/ractor-shim A shim to define Ractor by using Thread, if not already defined - eregon/ractor-shim

Ah it has `#<<`, but hasn't aliased it to `#send`: github.com/eregon/racto...

Also, probably doesn't matter, but it's the other way around in CRuby i.e., `#<<` is the alias.

01.11.2025 04:50 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
class Ractor::Port - Documentation for Ruby 3.5 class Ractor::Port: Port objects transmit messages between Ractors.

Has ractor-shim implemented `Ractor::Port#send`? That could be why if not. Ref: docs.ruby-lang.org/en/master/Ra...

01.11.2025 04:45 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
Release v0.8.0 Β· joshuay03/atomic-ruby Fix Ractor safety by @jhawthorn in #1 Make ArgumentError messages consistent Implement write barriers for Atom by @byroot in #2 New Contributors @byroot made their first contribution in #2 @jhawt...

github.com/joshuay03/at...

01.11.2025 04:37 πŸ‘ 2 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

I don't have an answer, but I'm figuring that out myself with what I'm building (not ready to share yet). There's a point where the copying/moving/freezing (i.e., message passing) overhead might outweigh the parallelisation benefits. The answer will vary by the payload and the type of work.

31.10.2025 07:14 πŸ‘ 2 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
Fix Ractor safety by jhawthorn Β· Pull Request #1 Β· joshuay03/atomic-ruby Unshareable objects can&#39;t be sent to ractors as today these objects are unsafe to concurrently modify. In the future (under Ractor-local GC) this will be even more broken and reading from the o...

Yes! I missed that. Clearly my Ractor coverage is lacking... @jhawthorn.com has already sent a fix: github.com/joshuay03/at.... I'll get that merged and released soon.

31.10.2025 07:00 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

2. The thing that clicked for me was when @jhawthorn.com referred to a ractor as a no-GVL block at Rails World. Rather than chucking a whole Rails app in there, you could find CPU intensive code paths that would choke the GVL, and delegate them to a ractor or few. Think complex parsing of strings.

30.10.2025 07:07 πŸ‘ 3 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

1. Could you clarify? I'm not aware of Ractors needing a C extension to work. Main limitation: C extension gems must mark themselves Ractor-safe. Shareable requirement on init/send exists, plus new semantics like move (may not last: bsky.app/profile/byro...). Docs: docs.ruby-lang.org/en/master/ra...

30.10.2025 07:07 πŸ‘ 0 πŸ” 0 πŸ’¬ 2 πŸ“Œ 0
Preview
GitHub - joshuay03/ractor-pool: A thread-safe, lock-free pool of Ractor workers with a coordinator pattern for distributing work A thread-safe, lock-free pool of Ractor workers with a coordinator pattern for distributing work - joshuay03/ractor-pool

Announcing RactorPool: github.com/joshuay03/ra...

Extracted from a project I'm building with Ractors. Currently requires Ruby 3.5 (3.5.0.dev). Goal is to have it stable for Ruby 4.0, when Ractors will be less experimental 🀞🏽

29.10.2025 16:48 πŸ‘ 24 πŸ” 3 πŸ’¬ 2 πŸ“Œ 0

Ah that’s unfortunate, that does seem like a tricky edge case… Being able to move in my case seems to be quite a bit more performant than both deeply copying (not surprising), and making shareable and duping just the objects I need to mutate in the receiver. Although, I haven’t properly benchmarked.

25.10.2025 12:07 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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Fix segfault when moving nested objects between ractors during GC by joshuay03 Β· Pull Request #14947 Β· ruby/ruby Fixes a segmentation fault when moving nested objects between ractors with GC stress enabled and YJIT. The issue appears to be a timing problem in the ractor move process. When moving objects, move...

I'm building something with Ractors and found a bug. Tried my bestℒ️ to fix it: github.com/ruby/ruby/pu...

Side note: Might just be me, but as a non-frequent contributor, building ruby/ruby and running tests seems to be much more convenient and efficient than it was a couple years ago.

25.10.2025 05:06 πŸ‘ 6 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

Time for a holiday?

07.10.2025 12:24 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
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#railsworld | 🍯 Joshua Young Attended the third edition of Rails World earlier this month along with Jason and JuliÑn, back in Amsterdam once again! A big thank you to Buildkite for sponsoring the three of us to attend this year....

September flew by pretty quickly… I kicked it off by attending #RailsWorld!

www.linkedin.com/posts/joshua...

29.09.2025 11:55 πŸ‘ 5 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

Was it the colonoscopy room?

22.09.2025 10:12 πŸ‘ 2 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

I’ve added support for distributed deployments: github.com/joshuay03/di...

Couple of ideas to follow up on:
- Profile dashboard
- Profile comparisons

22.09.2025 10:05 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

This is from a Datadog APM notebook I used to monitor the impact.

30.08.2025 23:21 πŸ‘ 0 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0

Haha yep, I have to remind myself from time to time as well.

30.08.2025 12:25 πŸ‘ 0 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

Yes, at the very end of a before_forkβ€”after doing any necessary closing of connections, shutting down threads, etc.

30.08.2025 10:55 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0
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Satisfying memory and CPU improvements after enabling Puma preloading + Process.warmup on one of Buildkite's services (our agent shard). Just rolled this out to all services - keen to see the broader impact!

30.08.2025 08:36 πŸ‘ 19 πŸ” 3 πŸ’¬ 3 πŸ“Œ 0

It probably hasn’t been released yet. I would first check if the change has been back-ported to the `8-0-stable` branch, and then whether it was actually included in a release. If not, and it’s already on the branch, it’ll probably be released in a 8.0.x at some point, else 8.1.x.

19.08.2025 22:29 πŸ‘ 1 πŸ” 0 πŸ’¬ 1 πŸ“Œ 0