Corey Kosak
Senior Developer at Deephaven Data Labs
Hoboken, New Jersey, United States
Summary
🤩
Rockstar🎓
Top SchoolCorey Kosak is a Senior Developer based in Hoboken, NJ, with 12 years of professional software experience and a background that spans finance, research, and large-scale engineering. He has held senior roles at Deephaven Data Labs and Google and brings a rare blend of production-grade systems work and deep technical rigor from years as a PhD candidate in computer science. His open-source contributions include performance-focused improvements and expanded test coverage to the croaring RoaringBitmap library—code used by analytics engines like ClickHouse and Apache Doris—highlighting a practical focus on efficiency and correctness. Earlier roles in quantitative finance and entrepreneurship underscore his ability to bridge algorithmic thinking with product and business needs. Known for optimizing low-level data structures and shipping pragmatic tooling, he pairs academic depth with hands-on delivery.
12 years of coding experience
16 years of employment as a software developer
Bachelor of Arts (B.A.), Computer Science, Bachelor of Arts (B.A.), Computer Science at Harvard UniversitySan Marin High SchoolPhD candidate, Computer Science, PhD candidate, Computer Science at Carnegie Mellon University
Stackoverflow
2,625reputation
393kreached
63answers
1question
datetime
top-5%
Github Skills (22)
bitmap10
c-language10
testing10
c1110
bitset10
c1710
bitmask10
bit10
bitmaps10
cprogramming-language10
data-structure9
algorithm9
datetime9
algorithms9
data-structures9
Programming languages (9)
Github contributions (5)
RoaringBitmap/CRoaring
Nov 2022 - Nov 2022
Roaring bitmaps in C (and C++), with SIMD (AVX2, AVX-512 and NEON) optimizations: used by Apache Doris, ClickHouse, and StarRocks
Role in this project:
Backend & Test Engineer
Backend & Test EngineerContributions:33 reviews, 10 commits, 10 PRs in 16 days
Contributions summary:Corey primarily focused on improving the `croaring` library's internal testing infrastructure. Their commits modified unit tests, changing assertions and improving test coverage. They also worked on optimizing the library's internal operations, particularly for 64-bit Roaring maps, and implemented new features such as initializer list constructors and assignment operators, enhancing the library's usability. In addition, the user addressed performance issues through the development of more aggressive fastunion implementations, demonstrating a focus on optimizing the library for efficiency.
cppclangroaring-bitmapsbitmapsbitset-library
kosak/deephaven-core
Jun 2021 - Apr 2025
Deephaven Community Core
Contributions:13 reviews, 55 PRs, 4070 pushes in 3 years 10 months
deephaven
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