Python doesnt really scale to large code bases, and refactoring is very hard.
Of course you need to have a structure within this codebase or you'll bump into the typical problems of large codebases. Some languages force you to work this way, we do it by enforcing certain rules in the lower level framework code of the project.
Also you need to keep pace, we are on the latest Python version and code is heavily typed. This project was started in the 2.7 days.
Well, otherwise, how would it have gotten to 2 million lines of code?
Adding lines of code and refactoring are different activities and discussions.
But I admit that there are challenges. For example startup time is ~30 seconds because that's the time it takes to import everything. This automatically means that running even a single test will take at least 30 seconds, to not bang your head against the wall we mostly write new code in a REPL so everything is already loaded.
If you have a pure ruby project and use it from day one, it probably works. But if you are starting a brand new project, just save yourself the pain and use TS.
> Of course you need to have a structure within this codebase or you'll bump into the typical problems of large codebases.
> Also you need to keep pace
I don't have the wherewithal to really dig into this now but to both those points I respond with a loving and resounding: "Duh!" (not directed at you)
What sort of project is it?
Typing definitely makes it a lot easier to navigate the codebase. But in the end maintaining any large codebase is a question of discipline which starts with simple things like code layout, class and function names, isolation of functionality.
Also it's hard to beat Django in terms of productivity. You can use type defs too.