Today I learned

LiveView Already Knows When Your Server Crashed

This week, I reviewed a pull request that added error flash handling to a Phoenix app. The JavaScript implementation seemed straightforward: listening for phx:page-loading-start, checking the socket connection, showing a popover for server crashes, and hiding it during navigation. It included two helper functions, an event listener, and a

Jujutsu

The Magic of `jj absorb`: Rewriting History Without the Pain

I was fixing a typo that spanned six commits With git, that meant an interactive rebase, editing each commit, resolving conflicts. With jj, it was one command: jj absorb.

elixir

Who Watches the Watcher? Debugging a Silent Langfuse Integration in Production

I deployed Langfuse for observability, but the dashboard stayed empty. Instead of redeploying with more logs, I used BEAM's :dbg to trace live function calls and hot-loaded fixes into a running Elixir system. This is the story of debugging the watcher itself.

elixir

Flaky Playwright Tests and Phoenix: A Distributed Systems Problem

The DBConnection.OwnershipError isn't a bug. It's the BEAM telling you you're building a distributed system wrong

ai

Speed Racer Gone Wrong: When CUDA Graph Optimization Killed My Inference Server

Why did my stable vLLM server keep crashing with CUDA OOM errors? The culprit: CUDA Graphs. For diverse workloads like structured JSON, graph capture + PyTorch's cache = a slow memory leak. I fixed it with one flag: --enforce-eager. Here's why I traded performance for stability.

llm

Ghostbusters: Who You Gonna Call When KV Cache Eats Your GPU?

My model was 60GB, and my GPU had 141GB. I should have had 81GB free, but I kept hitting OOM errors. The culprit? KV cache - an unseen memory hog that consumed 68GB without showing up in any config file. This article will explore how the context window and batch size are a zero-sum game.

ai

Fast & Furious Tensor Parallelism: GPU Heist Gone Wrong

Splitting a model across 4 H200 GPUs was expected to 4x throughput, but instead resulted in 2.8x worse latency and 35% lower throughput. Without NVLink, tensor parallelism causes more communication overhead than speedup, so sometimes 1 GPU outperforms 4

ai

Honey, I Shrunk the Model: When Quantizing 70B Parameters Broke Everything

I tried to shrink a 70B model from FP16 to FP8 to fit in my 141GB of VRAM. Spoiler: it broke everything. After testing 6 models and 3 quantization formats, I discovered that a 30B model in full precision outperformed every quantized 70B. Turns out precision matters more than parameter count.

neovim

Beyond IO.inspect: The Holy Trinity of Elixir & Phoenix Debugging with Neovim and Nix

A guide on how to set up the Elixir debugger in Neovim. This post explores the complete configuration using elixir-ls and nvim-dap, with a special focus on making it work seamlessly inside a Nix development environment.

nix

Remapping Keys on macOS with Nix-Darwin: My Battle with the EU Keyboard Layout

If you’ve ever used an EU keyboard on macOS, you know the struggle. The tilde (~) is bizarrely placed next to the Z key, and getting to a backtick (`) feels like solving a puzzle involving Shift and frustration. This post is about how I swapped the tilde and backtick keys

elixir

Advent of Code 2024: Day 6 - Guard Gallivant

Today I dove into path finding and state machines. The problem seemed simple at first - just simulate a guard's patrol route - but it turned into a fascinating puzzle about cycle detection. I tackled it with my usual four languages - Rust, Elixir, Go, and Haskell -

elixir

Advent of Code 2024: Day 5 - Dependencies and Ordering

I found myself in the North Pole's printing department today, helping an elf with their safety manual updates. The printer had strict rules about page ordering - certain pages had to be printed before others. As I stared at the long list of rules like "47|53&

elixir

Advent of Code 2024: Day 4 - Pattern Matching in Multiple Dimensions

The elves handed me what looked like a simple word search puzzle today. Find "XMAS", they said. Easy enough - until I discovered I needed to find it in every possible direction, including diagonals and backwards. Then part 2 hit me with X-shaped patterns, and suddenly I was

elixir

Advent of Code 2024: Day 3 - A Tale of State and Style

Its day three of Advent of Code. Today's challenge evolved from a straightforward exercise in multiplication into an elegant dance of state management and instruction parsing. Here I am again, with Rust, Elixir, Haskell, and Go to solve it. The Challenge: A State Machine in Disguise What started

elixir

Advent of Code 2024: Day 2 - When Languages Shape Our Thinking

aoc

Advent of Code Day 1: A Deep Dive into Language Characteristics

Solving Advent Of Code 2024 Day 1, using Elixir, Rust, Go and Haskell to how each language's philosophy and features guide us toward different solutions, even for the same simple problem.

nextjs

My First Adventure with Astro: A Journey from Next.js

Switching from Next.js to Astro for a static site? Here's my journey exploring Astro's 'zero JavaScript by default' approach, island architecture, and how it plays nicely with Cloudflare pages/workers.

rust

Writing Rust NIF code to convert encryption code from Elixir to Rust

In this article, we will go through what a NIF is, how to write safe NIF code using Rust and Rustler

elixir

Add latency tracking to phoenix live view apps.

Add latency tracking to phoenix live view apps

rust

Running scheduled cron jobs in Rust using tokio

Running periodic/scheduled tasks in Rust using tokio and async/await

rust

Making periodic http requests in Rust

Making http requests in Rust using reqwest, tokio, async/await and http proxies and cookies

nix

Configure max_connections for PostgreSQL using nix

How to configure max_connections value for PostgreSQL using nix

elixir

using elixir master branch using nix and nix-shell

There were some noteable changes that landed on the master branch in elixir today, related to improving the compilation, and I wanted to try out the latest version of elixir that was on the master branch. Since I use nix for setting up my projects, the latest version of elixir

elixir

Using variables inside binary pattern matching

I was refactoring a piece of code that I inherited in a codebase, which was parsing date from an external source in various formats into Date in elixir. The initial version of parse/1 function look something like the following: defmodule DateParser do def parse( <<_day_value::binary-size(

elixir

Tracing in Elixir/Erlang using :erlang.trace and GenServer

Recently, I wanted to trace a running Elixir system and see the messages that a function received. I was looking to inspect the params that it received and even manipulate the params to fiddle with some edge cases in the system. I knew that I could use dbg to start