Nine-tenths of Windows development now done on GIT, reveals Microsoft

Closed-source software developed on open-source

Microsoft has moved the development of the Windows operating system almost entirely to the open-source GIT environment.

The decision by Microsoft, which was announced in February, is now almost fully complete as the centrepiece of the company's OneCore project. This is intended to unify different strands of Windows development in a single path.

Nintey per cent of Windows engineers have made the switch, with the other 10 per cent expected to join by summer.

This will, theoretically, lead to the mythical beast that is Continuum finally working properly, although it doesn't signal a solution to the Android developer integration that was abandoned because it was proving uneconomically problematic.

After outgrowing SourceDepot, which previously housed its development needs, Microsoft has had to overcome the challenge of combining the 65 different repositories that have been housing Windows of late.

Even GIT has had to be customised to handle the 300GB and 3.5 million files that need to be stored, via a combination of algorithm improvements and a level of elasticity to stop the whole thing grinding to a halt under the weight of demands being placed on it.

The result is the Git Virtual File System (GVFS), which differentiates between what files are available locally and what aren't, and ignores the ones that aren't, bringing a git status command down to nine seconds from potentially hours.

At the moment, there are 8,500 commits and 1,760 builds every day, with that figure only set to rise as the system gets even more bedded in.

Some eyebrows may raise at the ideas of open source washing closed source, but it's worth remembering that Microsoft will have been obliged to donate its customisation to the community, and having Microsoft as a contributor is a pretty big deal.

Additionally, there's proxy servers constantly cloning roughly every 25 seconds, thanks to some big fat Azure bandwidth, so location of the engineer doesn't mess things up too much.

We may even see other tech giants start to collaborate on this type of project, as they all have their own issues.

The final switch-over for Windows engineers in the summer isn't the end of the story. Once that's all in hand the next stage is to move the rest of Microsoft over to Git.