Jacek Lewandowski
Committer at Apache Cassandra
Warsaw, Masovian Voivodeship, Poland
Summary
🤩
Rockstar🎓
Top SchoolJacek Lewandowski is a seasoned backend engineer and open-source committer based in Warsaw with over a decade of professional experience and more than two decades of hands-on development practice. He currently contributes to Apache Cassandra and is a Senior Software Engineer at DataStax, specializing in analytics platforms and distributed systems. His work on high-profile projects like Apache Spark includes fixing race conditions, null-pointer issues, and hardening TaskContext—demonstrating deep expertise in concurrency, fault recovery, and performance tuning. Academically rooted with a PhD in Information Technology and ongoing teaching at Warsaw University of Technology, he blends research-driven rigor with practical production delivery. Comfortable across JVM languages and data platforms (Scala, Java, Cassandra, Akka, Solr), he has a track record of improving robustness in mission-critical systems. Colleagues describe him as a meticulous problem solver who turns subtle concurrency bugs into long-term reliability gains.
11 years of coding experience
14 years of employment as a software developer
MSc, Data Communication and Telecommunications Management, MSc, Data Communication and Telecommunications Management at Warsaw University of Technology
Polish, English, Italian
Github Skills (12)
javas10
big-data10
spark10
concurrency10
java10
scala10
testing9
akka9
performance-optimization9
debug9
debugging9
sql8
Programming languages (13)
Github contributions (5)
apache/spark
Jan 2015 - May 2015
Apache Spark - A unified analytics engine for large-scale data processing
Role in this project:
Back-end Developer
Back-end DeveloperContributions:3 commits, 28 PRs, 109 comments in 3 months
Contributions summary:Jacek primarily contributed to the Apache Spark codebase by fixing bugs and addressing performance issues. Their work included resolving race conditions in Akka-related components, fixing null pointer exceptions in HiveClientImpl, and improving the system properties handling within SparkConf. They also addressed issues related to recovery mode factories and custom recovery modes. Furthermore, the user added functionality to TaskContext and improved the codebase's robustness and reliability.
analyticspythondata-processingsqlapache
jacek-lewandowski/cassandra-dtest
Jan 2021 - May 2024
Mirror of Distributed test suite for Apache Cassandra
Contributions:36 pushes, 19 branches in 3 years 4 months
testcasetest-datacassandraartemistesting
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