Meta's Sapling source-code management system

Meta has announcedthe open-source release of part of its internal source-code managementsystem, called Sapling.

Sapling began 10 years ago as an initiative to make our monoreposcale in the face of tremendous growth. Public source controlsystems were not, and still are not, capable of handlingrepositories of this size. Breaking up the repository was also outof the question, as it would mean losing monorepo's benefits, suchas simplified dependency management and the ability to make broadchanges quickly. Instead, we decided to go all in and make oursource control system scale.

Starting as an extension to the Mercurial open source project, itrapidly grew into a system of its own with new storage formats,wire protocols, algorithms, and behaviors. Our ambitions grew alongwith it, and we began thinking about how we could improve not onlythe scale but also the actual experience of using source control.

At this point, only the client side of the system has been released; thecompany "hopes to" release the rest later.