Roy Van Rijn
Director OpenValue Rotterdam at RotterdamJUG (Java User Group)
Rotterdam and The Hague Netherlands
Summary
👤
Senior🎓
Top SchoolRoy Van Rijn is a seasoned software leader and co-founder who directs OpenValue Rotterdam and helps run GrepS, bringing 15+ years of hands-on experience in software architecture, high-performance Java engineering, and agile delivery. A Java Champion, JavaOne Rockstar and Oracle ACE, he combines public-speaking and community leadership—founding and running RotterdamJUG—with deep low-level performance work (notably optimizing the One Billion Row Challenge using memory-mapped files, branchless parsing and SWAR techniques). He has moved between hands-on backend performance engineering and strategic roles at large organizations like Port of Rotterdam and municipal IT, translating complex requirements into pragmatic, high-throughput systems. Known as an all-round nerd, hacker and hobby mathematician, he blends practical engineering with curiosity-driven experimentation and active open-source involvement. Based in Rotterdam/The Hague, he mentors teams and builds developer communities while keeping a sharp focus on faster, better software delivery.
15 years of coding experience
15 years of employment as a software developer
Bachelor of ICT, Bachelor of ICT at Haagse Hogeschool/TH Rijswijk
English, German, Spanish
Stackoverflow
21reputation
824reached
1answer
0questions
Github Skills (13)
javas10
performance-optimization10
java10
bitwise10
algorithms8
data-structures8
algorithm8
data-structure8
ch8
inversion-of-control6
model-view-controller6
spring6
dependency-injection6
Programming languages (6)
Github contributions (5)
gunnarmorling/1brc
Jan 2024 - Feb 2024
Role in this project:
Back-end Developer / Performance Engineer
Back-end Developer / Performance EngineerContributions:28 reviews, 32 PRs, 50 comments in 1 month
Contributions summary:Roy's contributions primarily focus on optimizing the performance of a Java program for the One Billion Row Challenge. Their initial implementation involved parallel processing and BufferedReader. Subsequent commits demonstrate significant performance improvements through techniques like memory-mapped files, branchless parsing, and bitwise operations (SWAR). Further enhancements include the use of unsafe memory access, and the user demonstrates strong ability in performance optimization.
royvanrijn/Quantastic
Jun 2018 - May 2024
Contributions:6 pushes, 1 branch in 5 years 11 months
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