Daniel Szoboszlay

Lead Engineer at Klarna

Dániel fell in love with Erlang a decade ago, working for Ericsson in Budapest. After his project got outsourced to India he tried himself as a consultant. Unfortunately, it turned out that kicking off many projects but hardly ever seeing them finish is not everyone’s dream job, and working for short periods of time in far away places is not everyone’s wife’s dream scenario either. So he moved to Stockholm to join Klarna, and ever since he’s happily tweaking a big and old system for scalability and stability.

Upcoming conferences:

Daniel Szoboszlay
Code BEAM Lite Budapest

Testing for race conditions in real world software

Race conditions are a programmer’s worst enemy: hard to catch in tests, almost impossible to reproduce. But there came a new tool, and changed everything! This talk is about Klarna's experience with testing for race conditions using Concuerror. They were among the first industrial users of it, and it has been quite a journey! They ironed out some rough edges, learnt a whole new mindset about testing, discovered best practices, and even wrote a tool for testing distributed systems under Concuerror.


Give developers a head start on using Concuerror for testing their systems. To learn what’s possible and what’s not, and how to avoid common pitfalls.


Developers of concurrent systems.

Past conferences

Daniel Szoboszlay
Code BEAM STO 2019
17 May 2019
16.15 - 17.00

Useless performance optimisations on the BEAM for fun and... fun?

The race between Man and Machine for writing The Fastest Code is on since the first compiler has been invented. Now, I'm afraid when it comes to targeting x64, our chances of beating the Machine are negligible. But maybe with the BEAM we still hold a chance? Let's dig into BEAM assembly and find out whether we can show erlc a lesson or two!


Teach about how the BEAM VM works under the hoods and show some examples on what the compiler can and cannot optimise for you.


Anyone interested in low-level BEAM stuff. Or maybe compilers.