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Sébastien Allemand

@allemas.bsky.social
311 followers 285 following 871 posts

JVM Internals & Concurrent Software Design 🏗️ Deep dives into performance, concurrency & low-level mechanics ⚙️ Im not a t-shirt maker, views are my own

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Reposted by Sébastien Allemand
Loïc Mathieu @loicmathieu.fr · 29/05/2026
At Kestra, we take performance into consideration in all our features and try to improve it one release at a time. And it pays off regarding tremendous improvements made if we compare one year of improvements from 0.19 to 1.3 medium.com/kestra-engin...
medium.com
Performance Engineering at Kestra: From 0.19 to 1.3
How we made the orchestrator faster, leaner, and more scalable, one release at a time. By Loïc Mathieu, Lead Software Engineer, @Kestra
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Reposted by Sébastien Allemand
Legrugru @legrugru.fr · 23/02/2026
les mecs vont remplacer Cobol par du javascript écrit par IA on va tous bientôt vivre nus dans la forêt à manger des racines crues
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Sébastien Allemand @allemas.bsky.social · 22/02/2026
www.chrisgregori.dev/opinion/code...
chrisgregori.dev
Code Is Cheap Now. Software Isn’t.
The barrier to entry for building software has collapsed. The barrier to building something that matters hasn’t moved an inch.
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Sébastien Allemand @allemas.bsky.social · 19/02/2026
This !
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Sébastien Allemand @allemas.bsky.social · 17/02/2026
AI throws it right back in our faces what we don't know how to do in software is make explicit what is implicit in our code bases Then we'll say that AI does whatever it wants
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Sébastien Allemand @allemas.bsky.social · 06/01/2026
shbhmrzd.github.io/databases/tr...
shbhmrzd.github.io
Understanding Database Transactions and Isolation Levels
These blogs cover what I’ve learned so far, and I’ll continue to add more as I explore new topics.
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Sébastien Allemand @allemas.bsky.social · 01/01/2026
Maybe this will help someone someday... sebastienallemand.fr/posts/til-mu...
sebastienallemand.fr
TIL: Creating Periodic Streams with Mutiny in Quarkus
First of all : I wrote this article for myself so that I can refer back to it when I need to For a demo application, I needed to generate a large number of Kafka messages every second. Instead of usin...
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Reposted by Sébastien Allemand
Nina Beguš @ninabegus.bsky.social · 31/12/2025
Final interview for the year, translated from Slovenian by the podcasters: www.strasnohudi.si/novice/nina-...
strasnohudi.si
Why artificial intelligence reflects the culture of its creators — Strašno hudi
Author of the book Artificial Humanities , explains why digital assistants are biased, how the male-dominated culture of Silicon Valley shapes algorithms, and why philosophers should sit at the same ...
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Sébastien Allemand @allemas.bsky.social · 30/12/2025
I need to simulate and load test events in a demo My initial choice was Gatling as I thought I would get nice dashboards illustrating what was happening, but that wasn't the case by default, so I'm going to make a jar that will export the metrics Otherwise, I'm wasting too much time T__T
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Sébastien Allemand @allemas.bsky.social · 26/12/2025
I find it really interesting and important at a certain point to enrich one's profiling methods, we learn a lot I am creating a demo that aggregates fake events coming from an airplane from a topic and executes bad practices in the query layer The idea is to profile and show the different impacts
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Sébastien Allemand @allemas.bsky.social · 26/12/2025
Now all that's left is to finish the use cases, but I have enough to introduce the demo and examples!
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Sébastien Allemand @allemas.bsky.social · 26/12/2025
I encountered ‘lib/libasyncProfiler.dylib file system sandbox blocked open()’ when launching AsyncProfiler today Simply moving the folder to the user root directory resolves the issue. It appears that sandboxing is blocking in /u/Download ... T__T
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Sébastien Allemand @allemas.bsky.social · 26/12/2025
Use not consumed AI tokens, during vacations to generate poorly designed projects and fixing them with async-profiler and build demos :D
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Sébastien Allemand @allemas.bsky.social · 05/12/2025
www.uber.com/en-FR/blog/i...
uber.com
Improving MySQL® Cluster Uptime: Designing Advanced Detection, Mitigation, and Consensus with Group Replication
At Uber, engineers rely on MySQL® for applications that need relational databases. MySQL is the preferred choice for use cases that require ACID transactions and relational data modeling with a SQL interface. We support over 2,600 MySQL clusters. MySQL clusters follow the topology of a single primary and multiple-replica model. The replication is by default asynchronous, where the replica nodes poll the binlogs from the primary server. Only the primary node is used to serve write requests, and the read requests are served from replicas in a round-robin fashion with region affinity. The number of replicas required in the cluster depends on the read volume served by the cluster.
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Sébastien Allemand @allemas.bsky.social · 20/11/2025
I am completely in agreement with this approach, and it should be a daily reminder to people in management/staff/etc positions. I wanted to quote the parts with which I am in complete agreement. But in the end, I would have to quote the entire article
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Reposted by Sébastien Allemand
Ben @benjdd.com · 14/11/2025
Biggest takeaway from KubeCon: People want Neki badly. We're building the solution for scaling and managing huge Postgres databases. More to come, but in the meantime: neki.dev
neki.dev
Neki - Sign Up
Join Neki and stay updated with our latest news and updates.
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Reposted by Sébastien Allemand
rmoff 🏃‍♂️🫖🥓 @rmoff.net · 14/11/2025
A step-by-step guide to building a key-value database from scratch: www.nan.fyi/database - love the explainer/interactive animation in this
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Sébastien Allemand @allemas.bsky.social · 14/11/2025
Je rêve d’une industrie avec des incréments (mensonges / hypothèse) d’un seul jour mis en prod
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Reposted by Sébastien Allemand
Proton @proton.me · 31/10/2025
Last chance to turn it off. On Monday, November 3rd, Microsoft will start using your LinkedIn data for AI training. And remember, you're opted in by default. To toggle it off 👉 Account - Settings & Privacy > Data privacy > Data for Generative AI Improvement.
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Sébastien Allemand @allemas.bsky.social · 31/10/2025
Magic
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Sébastien Allemand @allemas.bsky.social · 30/10/2025
TIL When you create a URI that contains a path, for example: /api, this path is overwritten and not concatenated when you use .withPath on it
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Sébastien Allemand @allemas.bsky.social · 30/10/2025
memn0ps.github.io/hypervisors-...
memn0ps.github.io
Hypervisors for Memory Introspection and Reverse Engineering
Rusty Hypervisors - Windows UEFI Blue Pill Type-1 Hypervisor in Rust (Codename: Illusion) and Windows Kernel Blue Pill Type-2 Hypervisor in Rust (Codename: Matrix)
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Sébastien Allemand @allemas.bsky.social · 29/10/2025
I have to admit that I really enjoyed playing around with it for the headless FrankenJVM projects, but it's a good thing :D openjdk.org/jeps/451
openjdk.org
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Sébastien Allemand @allemas.bsky.social · 29/10/2025
This should be great and modernize Java integration with other low-level ecosystems/communities "Align the use of JNI and the FFM API so that library maintainers can migrate from one to the other without requiring application developers to change any command-line options" openjdk.org/jeps/472
openjdk.org
JEP 472: Prepare to Restrict the Use of JNI
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Sébastien Allemand @allemas.bsky.social · 29/10/2025
To reduce the safepoint bias problem, JFR now samples cooperatively: the recorder thread quickly saves the program and stack positions, queues a request, and lets the target thread capture its own stack at the next safe pause openjdk.org/jeps/518
openjdk.org
JEP 518: JFR Cooperative Sampling
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Reposted by Sébastien Allemand
Géopolitique @geopolitique.bsky.social · 29/10/2025
Autres exemples récents d’objets connectés / Un développeur a découvert que son aspirateur robot envoyait en continu des fichiers de logs, des mots de passe Wi-Fi non chiffrés, et cartographiait l’intérieur de son domicile à l’aide d’un logiciel de cartographie. codetiger.github.io/blog/the-day...
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Sébastien Allemand @allemas.bsky.social · 29/10/2025
Java will remove the Applet API, which was deprecated for removal in JDK 17 (2021) openjdk.org/jeps/504
openjdk.org
JEP 504: Remove the Applet API
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Hazel Weakly @hazelweakly.me · 27/10/2025
Don’t worry! This is good software! It serves its purpose. It serves that purpose damn well! Over a long period of time, too. (Which is why I really dislike the “utilitarianism-like value” based notions of what makes software good. It ends up equating empty vacuous drivel with impact)
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Dirk Eddelbuettel @eddelbuettel.com · 26/10/2025
duckdb-mlpack 0.0.2: mlpack is now a duckdb community extension Bringing mlpack machine learning to duckdb SQL dirk.eddelbuettel.com/blog/2025/10...
Screenshot of blog post at https://dirk.eddelbuettel.com/blog/2025/10/26#duckdb-mlpack_0.0.2 announcing that mlpack is now a duckdb community extension
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Sébastien Allemand @allemas.bsky.social · 26/10/2025
Avec cette JEP : jcmd pourrait désormais faire du diagnosticsur une JVM down à partir de son core dump J'ai très envie de jouer avec ! openjdk.org/jeps/528
openjdk.org
JEP 528: Post-Mortem Crash Analysis with jcmd
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Sébastien Allemand @allemas.bsky.social · 25/10/2025
Tout compte fait, les proces qu’on juge utiles sont en réalités les tâches qu’on effectue sous la contrainte (violence symbolique, économique whatever)
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Sébastien Allemand @allemas.bsky.social · 23/10/2025
A Software Engineer's Guide to Reading Research Papers blog.codingconfessions.com/p/a-software...
blog.codingconfessions.com
A Software Engineer's Guide to Reading Research Papers
My personal framework for reading research papers.
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Sébastien Allemand @allemas.bsky.social · 10/10/2025
L’avenir c’est construire des outils grâce a l’IA, qui sont imprécis et dont les résultats seront corrigé par l’humain. Jusqu’à ce qu’on progresse et rafine nos méthodes pour ensuite être de plus en plus précis dans les résultats. Nous retournons à notre réel status : techniciens.
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Sébastien Allemand @allemas.bsky.social · 19/09/2025
kerkour.com/announcing-p...
kerkour.com
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Reposted by Sébastien Allemand
Vipul Vaibhaw @vaibhawvipul.bsky.social · 19/09/2025
Built a small automatic differentiation engine with dynamic computational graph support deep learning framework in Rust from scratch. Gets to 98% accuracy on MNIST dataset in just 1 sec of training! github.com/vaibhawvipul...
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Sébastien Allemand @allemas.bsky.social · 19/09/2025
mostlynerdless.de/blog/2025/09...
mostlynerdless.de
How to waste CPU like a Professional - Mostly nerdless
In this week's blog post, you'll learn seven different ways to waste a specific amount of CPU-time. Number seven will surprise you.
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Sébastien Allemand @allemas.bsky.social · 17/09/2025
www.infoq.com/news/2025/08...
infoq.com
Netflix Revamps Tudum’s CQRS Architecture with RAW Hollow In-Memory Object Store
Netflix replaced a CQRS implementation using Kafka and Cassandra with a new solution leveraging RAW Hollow, an in-memory object store developed internally. Revamped architecture of Tudum offers much f...
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Reposted by Sébastien Allemand
Zineb Bendhiba @zinebbendhiba.com · 05/09/2025
👇👇👇
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Sébastien Allemand @allemas.bsky.social · 04/09/2025
adriano.fyi/posts/2023-0...
adriano.fyi
Choose Postgres queue technology
Introduction Postgres queue tech is a thing of beauty, but far from mainstream. Its relative obscurity is partially attributable to the cargo cult of “scale”. The scalability cult has decreed that the...
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Sébastien Allemand @allemas.bsky.social · 01/09/2025
On est lundi un peu d'humour
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Sébastien Allemand @allemas.bsky.social · 27/08/2025
jack-vanlightly.com/blog/2025/7/...
jack-vanlightly.com
Responsibility Boundaries in the Coordinated Progress model — Jack Vanlightly
Building on my previous work on the Coordinated Progress model, this post examines how reliable triggers not only initiate work but also establish responsibility boundaries . Where a reliable tri...
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Sébastien Allemand @allemas.bsky.social · 27/08/2025
I had problems with the Scala compiler, I just noticed that I had configured -Xss2m for the IDE... LOL
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Reposted by Sébastien Allemand
Conrad Ludgate @conrad.cafe · 27/08/2025
When working with async, you often need to call a function that would block the runtime. Turns out not all blocking functions are the same Tokio defines two kinds of blocking functions: IO bound and CPU bound. A close read of the tokio docs tells you to avoid CPU bound tasks in spawn_blocking
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Sébastien Allemand @allemas.bsky.social · 27/08/2025
Am I the only one who has noticed that there are a lot of inactive X accounts here? In a way, it's good because it allows you to meet new people :D
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Devnexus @devnexus.bsky.social · 26/08/2025
🔥 JVM performance matters. Check out our article recapping this year's session “Keeping Your Java Hot by Solving the JVM Warmup Problem.” with @speakjava.bsky.social! 👉 devnexus.com/posts/keepin... Devnexus '26 will bring even more insights like this. 🎟 Get super early bird tickets until Sept 1!
devnexus.com
Keeping Your #Java Hot by Solving the #JVM Warmup Problem, with Simon Ritter
In his session, Simon Ritter, Deputy CTO at Azul, takes on the persistent challenge of the “JVM warmup problem”—the performance lag that happens while the Ju...
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Reposted by Sébastien Allemand
Swift Connection @swiftconnection.bsky.social · 26/08/2025
Concurrency is still a challenge for many, making Approachable Concurrency very welcome. To discover how and why it can improve your way to Swift 6, we’re honored to host one of the true authorities on the topic, @mattie.bsky.social ! 👉 swiftconnection.io
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Sébastien Allemand @allemas.bsky.social · 27/08/2025
blog.octo.com/choisir-une-...
blog.octo.com
Choisir une plateforme d’API Management en 2025 : mon guide pour s’y retrouver  - OCTO Talks !
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Sébastien Allemand @allemas.bsky.social · 27/08/2025
Linux developers plan to drop legacy initrd support Almost all systems already rely on initramfs, so the change should simplify the kernel code www.phoronix.com/news/Initrd-...
phoronix.com
Initrd Support Could Finally Be On Its Way To Being Removed From The Linux Kernel
Linux's classic initial RAM disk 'initrd' support might finally be on its way out of the Linux kernel depending upon feedback from stakeholders
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Sébastien Allemand @allemas.bsky.social · 27/08/2025
- Without knowledge of each company’s semantics, AI agents are useless - Successful “Agentic BI” requires data intelligence, when the systems understand the company’s data and its unique business concepts - Agentic AI require: infrastructure, data and semantics www.databricks.com/blog/deliver...
databricks.com
Delivering Agentic BI: How to Unify Infrastructure, Data and Semantics
Agentic BI requires data intelligence, when AI understands the company’s data and its unique business concepts to truly unlock self-sufficiency and turbocharge productivity.
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Sébastien Allemand @allemas.bsky.social · 26/08/2025
www.youtube.com/watch?v=wo84...
youtube.com
Casey Muratori – The Big OOPs: Anatomy of a Thirty-five-year Mistake – BSC 2025
YouTube video by Better Software Conference
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