Michael Haggerty
Staff Software Engineer at GitHub
Berlin, Germany
Summary
🤩
Rockstar🎓
Top School
Top expert inComprehensive Systems and Network Programming
Michael Haggerty is a Staff Software Engineer in Berlin with 20 years of experience building robust back-end systems and developer tools, currently at GitHub. He brings deep expertise in Git internals, build systems, and graphing infrastructure—evidenced by contributions to high-profile open-source projects like git-sizer, msysgit, and graphite-web where he improved performance, refactored core components, and clarified complex algorithms. Formerly Head of Software Development at JPK Instruments, he blends leadership with hands-on engineering across testing, release automation, and technical writing (notably modernizing git-imerge and its documentation). Trained in rigorous physics at Berkeley and MIT, he applies mathematical clarity to practical engineering problems and often surfaces subtle correctness and efficiency improvements others miss.
21 years of coding experience
12 years of employment as a software developer
Bachelor of Science - BS, Engineering Physics, Bachelor of Science - BS, Engineering Physics at University of California, BerkeleyDoctor of Philosophy - PhD, Theoretical and Mathematical Physics, Doctor of Philosophy - PhD, Theoretical and Mathematical Physics at Massachusetts Institute of Technology
Github Skills (34)
algorithm10
git10
algorithms10
gnu-make10
restructuredtext10
cirrus-ci10
continuous-integration10
python10
scripting10
django10
graphite10
time-series10
bash10
rs10
cli-framework10
Programming languages (10)
Github contributions (5)
mhagger/git-imerge
Oct 2012 - Aug 2022
Incremental merge for git
Role in this project:
Back-end Developer & Technical Writer
Back-end Developer & Technical WriterContributions:3 releases, 526 commits, 70 PRs in 9 years 11 months
Contributions summary:Michael primarily focused on improving the documentation and the overall structure of the git-imerge tool. They added detailed explanations of the tool's functionality, including its incremental merge process, simplifying results, and technical aspects like storage and interaction with `git rerere`. Their contributions also involved updating the tool's name and adapting it for Python 3, demonstrating both code and documentation skills. The user also added and improved the HTML diagram output.
pythonmerge-conflicts
github/git-sizer
Oct 2017 - Dec 2022
Compute various size metrics for a Git repository, flagging those that might cause problems
Role in this project:Back-end Developer
Back-end DeveloperContributions:5 releases, 22 reviews, 442 commits in 5 years 2 months
Contributions summary:Michael's contributions focused on enhancing the functionality of the `git-sizer` tool. Their work involved refactoring the codebase by wrapping OID's in pending objects. These changes also include making internal methods private, and fixing tree path and memory management within the code. The user also addressed various aspects related to the Git object types (commit, tree, and tags) while improving the tool's overall efficiency and stability.
golang
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