The origin of this was from Uber ATC self driving division. We wrote the original submit queue inside of Phabricator and then it was eventually pulled out and made its own product.
It was fun to work on and find all the edge cases along the way.
Huh - are you sure? I was pretty sure that the original implementation came from the Android & iOS repos.
For those wondering “why is this needed”, IIRC the build took ~6 hours, so batching builds and testing were necessary to keep up