Guest post @ AppSignal – Debugging in Elixir with Observer

Folks at AppSignal have given me the opportunity to write a guest post on their Elixir blog, about the Erlang Observer.

Observer is one of the things I love to show as an introduction to Elixir to newcomers, along with two videos : https://www.youtube.com/watch?v=JvBT4XBdoUE (you know which one it is, in case you don’t, watch it, it’s Sasa Juric’s “The Soul of Erlang and Elixir”) and Bryan Hunter’s Waterpark presentation here : https://www.youtube.com/watch?v=pQ0CvjAJXz4.

Without reproducing the full post here, it’s a brief guide showing that Erlang’s Observer is more deep than that “cool GUI thing” usually only briefly mentioned.

We walk through launching Observer and use it to debug a “real” problem, a memory leak caused by a process that keeps creating references to large binaries. We run the leaky app on one node, and Observer on a separate hidden node and distribute both nodes so the monitoring doesn’t interfere with the measurements.

We then see how to use Observer’s tracing features : select a process, set up tracing, and watch things happening in real-time. The garbage collection traces show how the bin_vheap_size keeps growing and growing.

Here’s the post : https://blog.appsignal.com/2025/11/04/debugging-in-elixir-with-observer.html

Writing as a guest author, as opposed to on my own blog, was an interesting experience, even if I selected a topic that mandated a lot of pictures, which even if they aren’t worth a thousand words each, helped materialize the step by step process. It was my first time doing guest writing and overcoming a “personal style” for something more neutral took a fair bit of time. The editor team was super helpful and the overall experience has been great.

My time is now split between my SaaS Alzo one one side, another new tooling project for the construction industry on the other, a new contract on API designs for derived data graphs (in Elixir !) which I enjoyed a lot, long-ish distance running which I finally managed to pick up 2 years ago, and mention because I had already failed to pick up running 9 or 10 times before… 11 was the charm, so my blog is now a bit on the backburner. Still, it helped me on a lot of various facets and I’m glad I persevered writing on it those last three years. It has allowed me to meet new people, find work, and have a personal programming expressive space when I was in “crunch mode” on Alzo.

So, blog all you can, and happy hacking with Elixir :-) .