Well, there is the overhead of creating and removing namespaces each time a container is ran, or communicating with the Docker daemon. I think to most people i

Well, there is the overhead of creating and removing namespaces each time a container is ran, or communicating with the Docker daemon. I think to most people it would be negligible, but fb operates at a scale where these normally insignificant pieces matter. I would be interested to hear more about the _why_ of a system like this over containerization. edit: rwmj's comment has a good discussion over the benefits of this over containerization.