Pierre Zemb
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pierrezemb.fr
Pierre Zemb
@pierrezemb.fr
820 followers 650 following 220 posts
🧑‍💻 Staff Engineer @clever-cloud.com
🤩 Distributed and Database Systems
🚀 Co-leader Finistdevs.org
💪 Squash player
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pierrezemb.fr
👀 Turns out I'm #163 on the most active GitHub committers list in France
A non-trivial amount of credit goes to #ClaudeCode, my favorite coding partner these days!
committers.top/france
committers.top - Most active GitHub users in France
A list of most active GitHub users in France.
committers.top
February 14, 2026 at 11:01 AM
pierrezemb.fr
✍️ I just published "Simulating Leader Election on top of FoundationDB"

🧪 Can LLM-generated code be trusted for distributed systems? Only if you have the right feedback loop.

pierrezemb.fr/posts/simula...

#FoundationDB #rustlang #simulation
Simulating Leader Election on top of FoundationDB
Can LLM-generated code be trusted for distributed systems? Only if you have the right feedback loop.
pierrezemb.fr
February 5, 2026 at 8:52 AM
pierrezemb.fr
💡 In #FoundationDB, your reads determine whether YOU conflict. Your writes determine what OTHERS conflict with.

✍️ Wrote about OCC patterns for layer engineers: phantom conflicts, snapshot reads, atomic ops, and versionstamps.

pierrezemb.fr/posts/fdb-tr...
FoundationDB's Transaction Model for Layer Engineers
How optimistic concurrency control works in FoundationDB, and how to design data structures that stop fighting it
pierrezemb.fr
January 30, 2026 at 9:18 AM
pierrezemb.fr
I recently had an intense #squash match this morning, lasting an hour and ending with a 3-2 victory ✌️
Throughout the entire game, I maintained a heart rate consistently above 190 beats per minute 🥵
January 17, 2026 at 12:31 PM
pierrezemb.fr
✍️ I keep having the same conversation with colleagues about using LLMs for code. Finally wrote it down.
Planning, context, feedback loops, and why simulation + LLMs is a powerful combo.
pierrezemb.fr/posts/llms-f...
#llm #rustlang #testing
What I Tell Colleagues About Using LLMs for Engineering
LLMs amplify expertise, they don't replace it. Here's what works: planning, context, feedback loops, and building systems that let AI discover bugs.
pierrezemb.fr
January 15, 2026 at 8:19 AM
Reposted by Pierre Zemb
fasterthanlime.hachyderm.io.ap.brid.gy
RUST REFLECTION MVP HAS LANDED https://github.com/rust-lang/rust/pull/146923

THIS IS NOT A DRILL
Reflection MVP by oli-obk · Pull Request #146923 · rust-lang/rust
I am opening this PR for discussion about the general design we should start out with, as there are various options (that are not too hard to transition between each other, so we should totally jus...
github.com
January 10, 2026 at 8:17 PM
Reposted by Pierre Zemb
sunshowers.io
cool benefit of machine-executable specs -- they can be used by everyone, not just the author
my coworker finch: rain (they/she): another victory for RFD 619 as LLM guide: i got claude to rebase my TQ sled-agent API additions across the changeover to RFD 619 versioning by feeding it the full RFD and asking it to fix merge conflicts and refactor for conformity with the RFD. Worked like a charm, very little user direction needed other than accepting changes. has 3 fire emoji reactions
December 22, 2025 at 8:22 PM
pierrezemb.fr
🎄 Before heading to holidays, I wrote my 2025 year in review.

✍️ Back to engineering after 2 years of management. Built moonpool, a #FoundationDB simulation framework in #rustlang. Published 20 posts. Learned to work with LLMs. A year of going deeper.

pierrezemb.fr/posts/2025-y...
2025: A Year in Review
Reflections on returning to engineering, discovering simulation as a superpower, learning to work with LLMs, and the compounding value of years of distributed systems work.
pierrezemb.fr
December 26, 2025 at 10:01 AM
pierrezemb.fr
🔧 I just published a blogpost about specs in the #LLM era. Model checkers like #Fizzbee work for algorithms. But for APIs and business logic? The tooling doesn't exist yet.

pierrezemb.fr/posts/specs-...
Specs Are Back, But We're Missing the Tools
LLMs revived specifications. Model checkers like Fizzbee work for algorithms. But for APIs and business logic? The tooling doesn't exist yet.
pierrezemb.fr
December 19, 2025 at 9:04 AM
pierrezemb.fr
What Does a Database for SSDs Look Like? - Marc's Blog brooker.co.za/blog/2025/12...
What Does a Database for SSDs Look Like? - Marc's Blog
Maybe not what you think.
brooker.co.za
December 16, 2025 at 8:27 AM
pierrezemb.fr
🧪 How do you test #rustlang code that runs on top of #FoundationDB?

✍️ I wrote about designing simulation workloads: the patterns that find real bugs, the rules you can't break, and the pitfalls

pierrezemb.fr/posts/writin...
Designing Rust FDB Workloads That Actually Find Bugs
Patterns and principles for writing Rust simulation workloads that catch bugs before production does.
pierrezemb.fr
December 9, 2025 at 8:00 AM
pierrezemb.fr
This is an awesome podcast episode about debugging a Grown-up #ZFS Data Corruption Bug podcasts.apple.com/fr/podcast/o...
Grown-up ZFS Data Corruption Bug
Épisode de l’émission · Oxide and Friends · 26/11/2025 · 1 h 21 min
podcasts.apple.com
December 6, 2025 at 12:58 PM
pierrezemb.fr
Currently having a lot of fun modeling some internal spec in #fizzbee!
December 4, 2025 at 10:02 AM
pierrezemb.fr
How to (badly) start a week #squash
December 1, 2025 at 1:06 PM
pierrezemb.fr
I think I finally have a problem where I'd genuinely feel safer writing a TLA+ spec before even touching simulation code. Time to actually learn it. #tlaplus

lamport.azurewebsites.net/video/videos...
TLA+ Video Course
A Word of Warning These videos are not light entertainment. They require careful viewing and actual thinking. You may often stop a video to digest what you've just seen, and perhaps to skip back and…
lamport.azurewebsites.net
November 28, 2025 at 9:25 AM
Reposted by Pierre Zemb
andrewlamb1111.bsky.social
DataFusion 51.0.0 release blog: datafusion.apache.org/blog/2025/11...
November 25, 2025 at 8:50 PM
Reposted by Pierre Zemb
ahl.bsky.social
Hey hey! We recently tripped over a ZFS data corruption bug–introduced over 18 years ago! @bcantrill.bsky.social and I discuss with members of the Oxide team as well as Matt Ahrens, the co-inventor of ZFS.
Oxide and Friends 11/24/2025 -- A Grown-up ZFS Data Corruption Bug
YouTube video by Oxide Computer Company
youtu.be
November 25, 2025 at 11:23 PM
pierrezemb.fr
New books to finish the year!
November 22, 2025 at 1:51 PM
Reposted by Pierre Zemb
swallez.com
This meme is getting out of hand, but it's actually not far from reality 🤣
An evolution of xkcd #2347 with too many things that can break the Internet!
November 21, 2025 at 12:13 PM
pierrezemb.fr
A 'small' vanilla Kubernetes install on NixOS stephank.nl/p/2025-11-17...
A 'small' vanilla Kubernetes install on NixOS
— Stéphan Kochen, 2025-11-17
stephank.nl
November 19, 2025 at 10:51 AM
Reposted by Pierre Zemb
finistdevs.bsky.social
D'autres meetups ont des soucis de no-show, nous on a la chance d'avoir de l'over-show ! 26 inscrits, 37 présents pour le super talk de @snicoll.be sur #spring 4.

Parce que oui, nous somme toujours un JUG, FinistJUG forever ☕️ #java #spring

Merci encore à #Zenika #Brest pour l'accueil !
Stéphane Nicoll nous parle de Spring 4. Stéphane Nicoll nous parle de Spring 4.
November 13, 2025 at 6:23 PM
pierrezemb.fr
🤔 Have you ever wondered how #kubernetes caches #etcd?

✍️ I just published a new deep-dive into K8s watch cache: per-resource Cachers, waitUntilFreshAndBlock(), and progress notifications for quiet resources.

pierrezemb.fr/posts/diving...
Diving into Kubernetes' Watch Cache
Understanding how Kubernetes apiserver caches etcd, the 3-second timeout, and K8s 1.34 consistent read feature
pierrezemb.fr
November 12, 2025 at 8:13 AM
pierrezemb.fr
TLA+ Modeling of AWS outage DNS race condition muratbuffalo.blogspot.com/2025/11/tla-...
TLA+ Modeling of AWS outage DNS race condition
On Oct 19–20, 2025, AWS’s N. Virginia region suffered a major DynamoDB outage triggered by a DNS automation defect that broke endpoint resol...
muratbuffalo.blogspot.com
November 7, 2025 at 9:06 AM
pierrezemb.fr
Async QUIC and HTTP/3 made easy: tokio-quiche is now open-source blog.cloudflare.com/async-quic-a...
Async QUIC and HTTP:3 made easy- tokio-quiche is now open-source
We’re excited to announce the open sourcing of tokio-quiche, our async QUIC library built on quiche and tokio. Relied upon in our services such as iCloud Private Relay and our next-generation…
blog.cloudflare.com
November 7, 2025 at 9:02 AM
pierrezemb.fr
Did you know #FoundationDB's simulator randomly swaps disks between machines on reboot? 75% of the time. On purpose.

I wrote how this works: interface swapping, BUGGIFY chaos injection, and how we use it at @clever-cloud.com to build Materia.

pierrezemb.fr/posts/diving...
Diving into FoundationDB's Simulation Framework
How FoundationDB achieves legendary reliability through deterministic simulation, interface swapping, and one trillion CPU-hours of testing
pierrezemb.fr
October 30, 2025 at 8:22 AM