Björn Antonsson
Staff Engineer at Datadog
Stockholm, Stockholm County, Sweden
Summary
🤩
Rockstar🎓
Top School
Top expert inScala Ecosystem and Reactive Programming
Björn Antonsson is a Staff Engineer based in Stockholm with over two decades of experience designing high-throughput, performance-critical systems for finance, betting and infrastructure. He combines deep systems expertise—from compilers, OS internals and concurrency primitives to distributed architectures like event sourcing, CQRS and gossip-based replication—with hands-on implementation in Java, Scala, Rust and C. A founder of the JRockit JVM and long-time contributor to Akka, he’s driven telemetry and tracing work at Lightbend and performance-sensitive APM improvements at Datadog. Comfortable leading remote teams and prioritizing product needs, he favors automation, clean code and high test coverage to deliver reliable production systems. Less obvious: his work often targets the low-level bottlenecks (threading, scheduling, ID serialization) that dramatically improve real-world throughput and observability.
14 years of coding experience
26 years of employment as a software developer
M.Sc. Computer Science, M.Sc. Computer Science at KTH Royal Institute of Technology
Swedish, English
Stackoverflow
1,019reputation
51kreached
30answers
0questions
akka
top-5%
Github Skills (22)
testing10
distributed-tracing10
distributed-systems10
akka10
java10
apm10
scala10
javas10
performance-optimization10
concurrency10
serialization9
data-serialization9
messagepack9
documentation8
actor6
Programming languages (15)
Github contributions (5)
DataDog/dd-trace-java
May 2020 - Jan 2023
Datadog APM client for Java
Role in this project:
Back-end Developer
Back-end DeveloperContributions:1 release, 2300 reviews, 807 commits in 2 years 9 months
Contributions summary:Björn's commits primarily involved modifying the Datadog APM client for Java, specifically focusing on migrating and improving span and trace ID handling. Their work included refactoring the representation of trace and span IDs to a custom DDId class, implementing caching, and improving performance of various components, with further focus on testing and performance. Their contributions also involved adding support for trace and span IDs serialization, optimizing performance by minimizing string creation.
apm-clientapmbytebuddydatadoghqtracing
akka/akka
Mar 2012 - Nov 2017
A platform to build and run apps that are elastic, agile, and resilient. SDK, libraries, and hosted environments.
Role in this project:Back-end Developer
Back-end DeveloperContributions:899 commits, 49 PRs, 15 pushes in 5 years 9 months
Contributions summary:Björn primarily contributed to improving the reliability and maintainability of the Akka-based system. Their work focused on implementing features related to state transitions and failure handling in the cluster, resolving issues regarding connections and actor termination. They also introduced documentation updates on various topics. The code changes focused on correcting and improving several features to ensure reliable operation and provide robust solutions to common problem domains.
resilientactor-modelreactiveconcurrentdistributed-actors
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