Derrick Stolee

Principal Software Engineer, Azure DevOps

A former mathematician currently contributing to the Git community. Focused on performance.

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Introducing Scalar: Git at scale for everyone

February 12th, 2020
Git is a distributed version control system, so by default each Git repository has a copy of all files in the entire history. Even moderately-sized teams can create thousands of commits adding hundreds of megabytes to the repository every month. As your repository grows, Git may struggle to manage all that data. Time spent waiting for git ...

Updates to the Git Commit Graph Feature

November 11th, 2019
In a previous blog series, we announced that Git has a new commit-graph feature, and described some future directions. Since then, the commit-graph feature has grown and evolved. In the recently released Git version 2.24.0, the commit-graph is enabled by default! Today, we discuss what you should know about the feature, and what you can expect...

Exploring new frontiers for Git push performance

May 15th, 2019
In previous posts I've talked about performance improvements that our team contributed to the Git community. At Microsoft, we've been pushing Git to its limits with the largest and busiest Git repositories on the planet, improving core Git as we go and sending these improvements back upstream. With Git 2.21.0 and later you can take advantage ...

Supercharging the Git Commit Graph IV: Bloom Filters

July 16th, 2018
We've been discussing the commit-graph feature in Git 2.18 and how we can use generation numbers to accelerate commit walks. One area where we can get significant speedup is when presenting output in topological order. This allows us to walk a much smaller list of commits than before. One place where this breaks down is when we apply a filter ...

Supercharging the Git Commit Graph III: Generations and Graph Algorithms

July 9th, 2018
Earlier, we announced that Git 2.18 contains a new commit-graph feature, and we discussed the commit-graph file format. As shipped in Git 2.18, this file only speeds up commit walks by a constant multiple, due to parsing structured data from the commit-graph file. Today, we continue by talking about how we can use the idea of a generation ...

Supercharging the Git Commit Graph II: File Format

July 2nd, 2018
Earlier, we announced the commit-graph feature in Git 2.18 and talked about some of its performance benefits. Today, we'll discuss some if the technical details about how the commit-graph feature works, including some helpful properties of its file format. This file speeds up commit-graph walks so much that we were able to identify other ways ...

Supercharging the Git Commit Graph

June 25th, 2018
Have you ever run gitk and waited a few seconds before the window appears? Have you struggled to visualize your commit history into a sane order of contributions instead of a stream of parallel work? Have you ever run a force-push and waited seconds for Git to give any output? You may be having performance issues due to the number of commits ...

How to Contribute to Git (on Windows)

March 8th, 2018
Git was originally designed for Unix systems and still today, all the build tools for the Git codebase assume you have standard Unix tools available in your path. If you have an open-source mindset and want to start contributing to Git, but primarily use a Windows machine, then you may have trouble getting started. In fact, while responding ...

Microsoft’s Performance Contributions to Git in 2017

January 11th, 2018
Visual Studio Team Services (VSTS) hosts the largest Git repository in the world: the Windows source code. Keeping a primary copy of the code available in the cloud and having it be performant while being updated by over 4000 users at the same time is a monumental achievement, but it is only useful if engineers can use the core Git client on ...

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