Microsoft isn't just using open source, it's reportedly now using the Git version control system to build Windows. The original developer of proprietary software is now relying on open source to build the Windows operating system! Who would have thought?
You may not have noticed, but in 2013, Microsoft announced the roadmap for adding Git support to its Visual Studio suite of development tools and Team Foundation application management technologies.
Later that year, Microsoft technical partner and Team Foundation lead Brian Harry announced that Microsoft would now support Git as a source-code-control platform.
The idea didn't appeal to everyone at Microsoft, but as Brian Harry on his blog at the time, "the more we looked at it, the more it seemed to make sense."
Over the years, Microsoft has made its own significant open source contributions to Git. In 2017, the open source, MIT-licensed Microsoft Git Virtual File System (GVFS) was released. GVFS allowed Microsoft product teams to upgrade their Git client to access vast open source repos.
Since then, Microsoft has begun moving all of its Windows code to Git and GVFS. The project appears to be largely complete, and Microsoft is reportedly reaping the rewards of open source by creating the largest Git repo on the planet.
Brian Harry says: “Over the past 3 months, we have largely completed the development of Git/GVFS on the Microsoft Windows team. It was no small feat.
The Windows code base is about 3.5M files and, when connected to a Git repo, results in a repo that is about 300GB.”
These were just the files.
“The Windows team is about 4,000 engineers and the engineering system produces 1,760 daily “lab builds” across 440 branches in addition to thousands of validation builds pull requests.”
Harry admitted that this was a terrifying experience:
“The first and biggest jump happened on March 22nd when we were launching the Windows OneCore team of 2,000 engineers. Those 2,000 engineers worked on Source Depot on Friday, went home for the weekend, and came back Monday morning to work on Git. The team members held their breath all weekend, praying that there wouldn’t be a problem on Monday.”
“To my great surprise, it went very well and the engineers were productive from day one.”
Today, almost all Windows developers work in Git. In the coming months, the last 500 developers will move to the Git platform.
Let's look at some numbers:
There are over 250,000 Git commits in the repo history, over the last 4 months.
8,421 pushes per day (on average)
2,500 pull requests, with 6,600 reviewers per workday (on average)
4,352 active issues
1,760 official builds per day
Microsoft continues to tune GVFS for remote use.
Impressed? Microsoft certainly is, and that's why it uses GVFS. GVFS is an open source project and you can try it out. All you need to do is download and install it. Then you can create a Visual Studio Team Services account with a Git repo and you're good to go. Other Git programs include Atlassian SourceTree and Git Tower.
Ironically, there is currently no Linux Git client that supports GVFS. Saeed Noursalehi, a Microsoft program manager, wrote on the GVFS bug list: “Yes, we definitely want to support Mac and Linux, and we are looking for people with experience in file systems for those platforms.”
The creator of Linux and Git, Linus Torvalds, once stated:
“If Microsoft ever makes apps for Linux, that means I won.”
I think since Microsoft uses Git for Windows development, this can be considered a win.
