It’s big. Really big. Just looking at the timetable is daunting, let alone choosing which talks to attend.

People come to FOSDEM from everywhere. I don’t think I’ve ever heard such a wide selection of languages at the same place. It really brings home just how massive FOSS is, and how many people care about it.


I’ve never been to Brussels before. If there’s one regret about my FOSDEM trip, it’s that I didn’t have more time to spend in this beautiful city which appears to be full of fun, friendly people. I would definitely recommend visiting with some time to spare; I certainly will be again.

Also, the beer. Oh my, the beer.

FOSDEM itself is hosted by Université Libre de Bruxelles (ULB). The event takes up a fair chunk of the campus. This was again quite daunting, but the organisers took a lot of effort to make it easy to navigate from place to place with a lot of clear signage and timetable information.


There were stands run by all the FOSS projects we know and love. The stands were an odd experience compared to a “normal” conference.

Generally at conferences you have a few big corporations and a bunch of smaller companies. Everyone wants to sell you something you’ve never heard of and get your details so they can send you spammarketing information.

Not at FOSDEM. Most of the time I found myself going up to these fantastic projects like Debian, GitLab or Apache and the conversation was mostly limited to “you guys are amazing, thanks for doing what you do”. It was a good chance to find out what teams were working on in the FOSS world. In some cases, like with Matrix for me, it was useful to be able to go and chat to them after seeing a talk about their project to get some more detail. The stands also provided the opportunity to donate to projects by buying a wide array of merchandise.

I learned about a few projects I hadn’t heard of too, like PostGraphile, a tool to create a GraphQL API pointing at your existing PostgreSQL database; IsardVDI, a really neat tool to manage KVM virtual desktops targeted at classroom-type environments; and Bazel, a build tool to help you only run the tests you need to.


I managed to select a good few talks in the end. Sadly, some of them (looking at you, HTTP/3) were so popular they weren’t possible to get in to. Luckily, all of them are recorded and available to view on the FOSDEM site.

Here’s a sample of those I attended. I recommend you follow the links and check out the videos yourself if you find them interesting.

What’s new in PostgreSQL 11 — Magnus Hagander

My colleague Magnus presented what’s new and magical in PostgreSQL 11. Some of the ones that interested me were:

  • RANGE BETWEEN, allowing you to operate on windows in your data in ranges based on any sortable data type

  • Stored procedures, making it much easier to migrate from… other database systems which one might encounter when you need to embed transactions inside your code

  • Logical replication of TRUNCATE, which was confusing by its absence

And of course general improvements in performance, with better use of parallelism.

If you’re a PostgreSQL user I’d suggest checking the talk out yourself to get all the details.

Java 4..12, Kotlin, Code Coverage and their best friend — bytecode: scandals, intrigues, investigations — Evgeny Mandrikov

A talk I really enjoyed that I selected largely at random. Evgeny Mandrikov works on JaCoCo. They build code coverage information by looking inside Java class files which allows them to work with multiple JVM languages. Unfortunately, it turns out that javac outputs code that… isn’t quite what you’d expect. It can also be extremely different for the same code depending on the target JVM version. The talk had a series of interesting examples of compiler output bytecode demonstrating these issues and proving that when you’re reverse engineering, sometimes you just have to make a guess.

Netflix and FreeBSD — Jonathan Looney

This was a slightly disappointing talk. I was hoping for some information about the advantages of FreeBSD for this sort of work, but the talk focussed a lot on the advantages of working closely with upstream FreeBSD and of publishing Netflix’s improvements. That’s very true, but it’s an odd pitch to a room full of people at an open source conference.

There were some interesting details about the hardware Netflix use in their CDN caches and the areas they have to focus on for performance.

Matrix in the French State — Matthew Hodgson

The French government were looking for a new communication tool and landed on Matrix. This talk covered some of the design and deployment of this solution, and the challenges involved. He also talked about the feedback into the open source project and the improvements we can expect or access now.

I found this talk enthralling, because I had reviewed Matrix for use as a corporate communications tool a couple of years ago when it was much more basic, and it was delightful to see how far they have come. Developments like easily verifiable end-to-end encryption in this sort of tool just sound marvellous. The improvements they have made in the development version of Riot bring it up to par with (dare I say better than?) the major players in this field. Definitely a project to keep an eye on.

Introduction to the BASIC Engine — Ulrich Hecht

Given that a Retrocomputing track existed, it would be rude not to attend. This talk about building a sub-€10 computer to run BASIC sounded like fun. And indeed it was! Ulrich Hecht talked about his motivations for building such a computer, the hardware he selected and what’s involved in building the machine. He was specifically focussed on a machine that had good graphics and sound capabilities, which he demonstrated. It reminded me a lot of programming for the C64 or Amiga (the BASIC Engine has a blitter).

2019 - Fifty years of Unix and Linux advances — Jon ‘maddog’ Hall

It was fantastic to have an opportunity to see Jon ‘maddog’ Hall talk in person. He was engaging and enthusiastic as he talked about his experiences living through the entire history of Unix and Linux. He ran out of time in the end, but luckily a riot was prevented when he was allowed to finish.

There were various events and people marked with asterisks in the presentation to denote that given time in the pub, more stories would be available. I would dearly have enjoyed to hear those stories!

I really can’t capture his particular charm and humour here, so I strongly suggest you check out the talk yourself.


I’d like to thank the fantastic people who take the time and effort to organise this event. Having been marginally involved in running conventions, I’ve seen how hard it can be to wrangle these things. And this event is ridiculously huge — the statistics in the closing talk had us eating 200kg of waffles alone! The effort involved must be herculean. So, yeah, thanks!