Josh Karpel
Principal Machine Learning Engineer at Workday
Madison, Wisconsin, United States
Summary
👤
Senior🎓
Top SchoolJosh Karpel is a Principal Machine Learning Engineer with 11 years of experience translating physics research into production-grade software and scalable ML systems. He holds a PhD in Physics from UW–Madison and has a strong track record building high-throughput computing tools, simulation code, and orchestration for large-scale data movement. At Workday he has progressed from ML Engineer to Principal, focusing on robust, performant back-end systems and deployable ML infrastructure. An active open-source contributor, Josh has improved parallelization in pymoo, added test-framework features to the popular Python testing tool ward, and optimized Ray Serve internals—work that blends performance tuning with developer ergonomics. Colleagues value his ability to bridge domain science, system administration, and production engineering, and he often surfaces subtle edge-case fixes (like pickling and fixture-handling) that improve reliability at scale. Based in Madison, WI, he combines deep scientific modeling experience with pragmatic software craftsmanship to deliver reproducible, high-throughput ML solutions.
11 years of coding experience
10 years of employment as a software developer
Doctor of Philosophy - PhD Physics, Doctor of Philosophy - PhD Physics at University of Wisconsin-MadisonBachelor of Arts (B.A.) Physics and Mathematics, Bachelor of Arts (B.A.) Physics and Mathematics at University of Colorado Boulder
Stackoverflow
2,116reputation
146kreached
91answers
1question
python
top-5%
Github Skills (31)
pytest10
parallelization10
python10
apidoc10
sphinx10
testing10
test-framework10
api10
performance-optimization10
ray10
documentation10
optimization10
test-automation10
python-bindings9
multi-process9
Programming languages (13)
Github contributions (5)
darrenburns/ward
Apr 2020 - Jul 2021
Ward is a modern test framework for Python with a focus on productivity and readability.
Role in this project:
Back-end & Test Automation Engineer
Back-end & Test Automation EngineerContributions:21 reviews, 40 commits, 13 PRs in 1 year 2 months
Contributions summary:Josh primarily contributed to the development of the `ward` testing framework for Python. Their work focused on adding new features, specifically the `--fixtures` CLI option for displaying fixture information. They also refactored the code to improve fixture handling and information display, including a move towards using Rich for enhanced terminal output and incorporating progress tracking during test execution. Additionally, the user implemented improvements to the testing framework related to edge cases such as tests and fixtures exiting unexpectedly.
pythontesting-frameworkproductivitytestingtest-framework
htcondor/htcondor
Apr 2018 - Sep 2020
HTCondor source repository, formerly the Condor Project
Role in this project:Technical Writer
Technical WriterContributions:257 commits in 2 years 5 months
Contributions summary:Josh primarily contributed documentation improvements, including adding new documentation pages, correcting tutorial links, and improving docstrings for various modules. They focused on clarifying descriptions, fixing formatting issues, and restructuring documentation to improve overall clarity and organization. The contributions involved extensive changes to the documentation for both the python bindings and the core HTCondor features.
slurmdistributed-computingdistributed-systemshpchtcondor
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