FOSDEM19 it's just over, and here are my main highlights!


After arriving to Brussels, and then to the venue, I wasn't on time for the first talk that interested me, and then I couldn't make it into the HTTP/3 talk because the room was full, so I decided to get an introduction to the conference by visiting the stands, and networking.

The first talk I attended was VNF development made easy with netmap, which was very good. Even though it's a topic different than what I usually work with, it was a really interesting talk with snippets of C code and low-level operations in the slides, deep technical insights into the details of networking, and quite enjoyable.

In the same development room followed a talk introducing ONOS, a software-defined networking platform (kind of like a "kernel" for networking in an architecture) written in Java, and with a large community, sponsored by big companies.

From the databases track, the talk Postgres goes to 11! was a really good introduction to the history of PostgreSQL, how the project started, its roots, what has been going on lately, how's the development process (the commit fests, and its tracking system are a wonderful idea, that I wish other projects adopt!); and why it's important to always update the engine (even minor releases contain important changes and bug-fixes!). It also briefly covered the last new features that have been added to the database, and what can be expected for the next release, 12.

After that it was time for a talk about how Netflix uses FreeBSD for its streaming platform. It started with a great introduction to their platform and architecture (impressive as you might expect, for instance their CDN handles 100Tb/s!), and what are the main drivers for their technical decisions (e.g. speed vs. costs, optimization of the workloads, etc.). After that introduction, it was time to move to the core of the presentation, and explain their software engineering approach. The main takeaway was their aggressive strategy to incorporate changes from FreeBSD as fast as possible, by keeping track of the "head" of the repository rather than one of the stable branches. Through development cycles of ~5 weeks, it's possible to integrate with the new features faster, pay the price of merging early, and achieve a faster velocity of delivery.

The next talk was PostgreSQL vs. fsync an amazing talk. It provided a deeply technical insight on the internals of the database, and how it does to implement the I/O stack by relying on the [fsync]{.title-ref} syscal, and why everybody assumed it worked in a way when in reality it was doing something different (here there are more information for the curious).

The last talk of the day, was Walking through walls PostgreSQL ♥ FreeBSD. Another superb talk. One of the ones I enjoyed the most, actually. Again, super technical, in this case it all started by an analysis of how does PostgreSQL perform on BSD systems (spoiler alert: no so well by around ~2014). After that, there were several changes being made, both in FreeBDS and in PostgreSQL in order to make it faster. It was a good technical review of operating systems internals (for instance, the component of PostgreSQL that sets the process name as the query that's currently running, was slow because in BSD, it relied on a function of the standard library that used two system calls, therefore a new function -- setproctitle_fast(3)-- was created to accomplish the same without system calls at all, achieving a 10% of performance gain). There were multiple other examples like this one that made the presentation very enlightening. Actually it was closely related to the previous one in the sense that the "fsyncgate" was mentioned, and the dilemma of relying on the operating systems capabilities vs. implementing direct I/O reappeared.

That was the first day, packed with technical talks, and a lot of knowledge. But it wasn't quite over yet: there was still a nice dinner organized by the Python development room ahead.


The morning was focused on the Python development room. The first talk I was able to attend was about GraphQL, which is a relatively new technology for web APIs development, that I have worked in the past with.

Then it followed a talk about how to write pylint plugins. It makes me happy to see there are people who realise that the quality, and standards, in the code are something that has to be enforced by tools, and not left out for people to the code review phase.

The next talk was about a library for managing configuration in services, which was quite interesting

After that one I presented my talk about coroutines and asynchronous programming:

Then, more talks, more networking, and the last talk was Breaking PostgreSQL at scale. Another solid talk (this track is actually one of the best). It explored several parameters, constraints, and considerations to take into account when dealing with databases of different scales, starting with small ones (<=10Gb), medium ones (~100Gb - 1TB), or large ones (>1TB). It's interesting to see how at the beginning you can get away with pretty much anything, but as the data grows, more fine tuning has to be done, and different strategies (e.g. sharding, or changing the backup policy), come into play.

And that was the end of the conference for me.

Final Remarks

There were lots of talks that I wished to, but couldn't attend, for a variety of reasons (transportation, logistics, some rooms were full and didn't allow more people to get in, overlaps in the schedule, etc.) I will try to watch the videos for these talks as they're being released, along with following up with the slides.

Besides this perfectly understandable mishap, I really enjoyed the conference, and learned a lot, about many different things (cloud computing, databases, infrastructure, programming languages, and operating systems).

It was great to attend a conference packed with highly technical talks (it's really lovely to spend a day leaning through solid presentations with slides full of code snippets, and configuration files), and I think that's a great differential compared to many other previous conferences I attended in the past (probably the exception being the Kafka summit in London last year): the content is highly technical, and focused on technology.

FOSDEM is great for expanding the technical portfolio because the conference offers multiple tracks in parallel and with different technologies.