You have no idea about their codebase, the implementation details of their features nor how they counted the lines (comments included?). So stating that it’s dumb is beyond ridiculous.
You are right in that it’s certainly a high LoC count for Python, but still...
And yes, knowing nothing else about their code base than A) It's in Python, and B) it's several million lines of code, I feel very confident that there is at least an order of magnitude too much of it. Instagram is just not doing anything that complicated.
(I should mention I specialize in maintaining and refactoring legacy Python code. I know what I'm talking about here.)
Features that are "not complicated" can actually very easily be "very complicated" at scale. Which Instagram does have. 500 million users, every single day.
If you need several millions of lines of Python to do what Instagram server does, the code is bloated.
My bet is that they let too many Java devs loose on the code base, without experienced Python devs reviewing the commits and managing the deluge of unnecessary classes. I've seen it happen before.
>If you need several millions of lines of Python to do what Instagram server does
I have this feeling that you're probably not all that aware of 95% of what their code actually does, and thus probably not in a position to make judgements as to whether their code base is truly bloated relative to what it does.
From a user's perspective, Instagram has:
a) a way to post pictures/videos/sound recordings to a public feed. The pictures can include overlays of links to other users, to other posts, to song lyrics that play in sync with the music, etc etc. Users viewing their posts get the ability to comment/like/link, with automatic language detection and translation on demand.
b) a way to see how other users interact with their posts, allowing comments, seeing views and other analytics, monetizing etc etc
c) Provides advertisers with the ability to place stories (stories are a stream of short-lived (24 hours) video/audio posts that users see) or posts (that can be static/video/audio), with links to external sites, purchasing direct links ("Shop now"/"Buy this") etc
Instagram is much more than a stream of user images.
That doesn't include all the "back office" stuff like spam/reporting/censorship/language translation etc etc.
You are right in that it’s certainly a high LoC count for Python, but still...