Mikael Pettersson
Lead Engineer at Klarna
Sweden
Summary
🤩
Rockstar🎓
Top SchoolMikael Pettersson is a Lead Engineer with 30+ years of deep systems and compiler expertise, currently shaping core transaction and storage architecture at Klarna. He combines academic rigor (PhD in Computer Science) with hands-on mastery of portable C, assembly across many ISAs, kernel internals, JITs, runtimes and dynamic binary instrumentation. His open-source contributions include fixes and performance-focused refactors in high-profile projects like GCC and Erlang/OTP, and improvements to an Apache Kafka client for Erlang/Elixir, reflecting both low-level optimization skills and real-world distributed systems experience. Known for formal language semantics and teaching compilers and OS courses, he brings a rare blend of research-driven thinking and pragmatic engineering that spans from register allocation to large-scale payment systems.
13 years of coding experience
21 years of employment as a software developer
Doctor of Philosophy (PhD), Computer Science, Doctor of Philosophy (PhD), Computer Science at The Institute of Technology at Linköping UniversityNatural Sciences, 5.0 average (A+), Natural Sciences, 5.0 average (A+) at Sannarpsgymnasiet, Halmstad
English, Swedish, German
Stackoverflow
1reputation
0reached
0answers
0questions
Github Skills (28)
client-library10
erlang10
elixir10
compiler-development10
testing10
kafka10
c1110
otp10
gcc10
c1710
performance-optimization10
6800010
bit-manipulation9
crossbuild9
concurrency9
Programming languages (8)
Github contributions (5)
kafka4beam/brod
Nov 2019 - Jun 2021
Apache Kafka client library for Erlang/Elixir
Role in this project:
Back-end Developer
Back-end DeveloperContributions:1 release, 30 reviews, 31 commits in 1 year 6 months
Contributions summary:Mikael primarily contributed to the `brod` library, an Apache Kafka client for Erlang/Elixir. Their work involved refactoring and optimizing producer buffer logic, ensuring correct handling of produce requests and acknowledgements. They also focused on code cleanup and consistency, renaming variables and functions for clarity, and de-closurizing functions for performance. Furthermore, the user addressed testing improvements.
apache-kafkaelixirerlangkafkaklarna-featured
erlang/otp
May 2014 - Nov 2022
Erlang/OTP
Role in this project:Back-end Developer
Back-end DeveloperContributions:47 reviews, 88 commits, 69 PRs in 8 years 7 months
Contributions summary:Mikael primarily focused on improving the Erlang/OTP codebase by cleaning up and optimizing the floating-point exception handling in `sys_float.c`. This involved inlining functions, removing redundant comments, and moving common code into subroutines. They also addressed integer truncation issues in `erl_unicode.c`, enhanced the base64 decoding algorithms, and fixed formatting issues within HiPE debug BIFs. Additionally, the user contributed to preventing memory leaks and improving code quality, demonstrating a strong understanding of the Erlang/OTP ecosystem.
erlang
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