Jeff Hostetler
Staff Software Engineer At GitHub
Durham, North Carolina, United States
Summary
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Rockstar🎓
Top SchoolJeff Hostetler is a Staff Software Engineer at GitHub with 11 years of professional experience and a multi-decade track record building high-performance version control systems and developer tools. He has led core contributions to Git, Git for Windows, Scalar and libgit2—delivering algorithmic and multi-threaded performance improvements, telemetry for large-repo diagnostics, and targeted bug fixes that improve stability and scaling. Prior roles include principal engineering at Microsoft and founding engineering work at SourceGear, where he created widely used tools like DiffMerge and built a DVCS with integrated tracking and wiki features. Jeff blends deep systems-level expertise (file system caching, race conditions, refactorings for porcelain V2 output) with strong QA and test-automation practices, often enhancing observability in complex test harnesses. Based in Durham, NC, he pairs academic grounding in mathematics and computer science with a pragmatic focus on shipping robust, debuggable software for massive repositories. An understatement: many large-scale Git performance wins used in Windows and enterprise monorepos trace back to his instrumentation and optimization work.
11 years of coding experience
28 years of employment as a software developer
Master's Degree, Computer Science, Master's Degree, Computer Science at Purdue UniversityAssociate's Degree, Computer Science, w/ Distinction, Associate's Degree, Computer Science, w/ Distinction at Indiana University-Southeast
Stackoverflow
1reputation
0reached
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Github Skills (23)
git10
debug10
libgit210
testing10
nunit10
memory-management10
c1110
functional-testing10
c1710
libgit2sharp10
performance-optimization10
version-control10
error-handling10
test-automation10
winapi9
Programming languages (11)
Github contributions (5)
git-for-windows/git
Jun 2016 - Mar 2022
A fork of Git containing Windows-specific patches.
Role in this project:
Back-end Developer
Back-end DeveloperContributions:45 reviews, 331 commits, 35 PRs in 5 years 10 months
Contributions summary:Jeff was involved in enhancing performance optimization within the Git for Windows project, specifically within the fscache component. Their contributions included modifications to the FSCACHE implementation to remember "not found" directories, improvements to the "add" command, and fixes to address a regression related to handling ".gitignore" files. The user also introduced and applied a trace key for monitoring the performance of FSCACHE operations.
version-controlwindowsgit-hookslibgit2patches
git/git
Aug 2016 - Dec 2022
Git Source Code Mirror - This is a publish-only repository but pull requests can be turned into patches to the mailing list via GitGitGadget (https://gitgitgadget.github.io/). Please follow Documentation/SubmittingPatches procedure for any of your improvements.
Role in this project:Back-end Developer
Back-end DeveloperContributions:1 review, 212 commits, 2 comments in 6 years 5 months
Contributions summary:Jeff primarily contributed to the Git source code, specifically focusing on refactoring and extending functionality related to status reporting. They implemented enhancements for the porcelain V2 output format, including branch and tracking information. Furthermore, the user introduced a mechanism to control and reduce the time needed to show the branch information when running 'git status'. The user implemented changes to ensure file system events are handled and to optimize code performance and reduce potential bottlenecks.
hacklanggit-clientmercurialfollowlibgit2
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