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Comment by nostrademons | Hacker News Reader

YouTube did rewrite on Google infrastructure - there was a paper they published c. 2008 about how they were leveraging Google's cloud to scale. It was largely back-end stuff; IIRC they moved from MySQL to BigTable, adopted Google's blobstore & CDN, integrated with Google's machine-learning systems, etc. They were allowed to choose which parts of Google's infrastructure they wanted, though. AFAIK the front-end was still Python when I left Google the first time in 2014, and it wouldn't surprise me if it still is now.

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"adopted Google's [...] CDN"

Google's CDN was largely written for YouTube.

It is mostly Java now. Backend ones are migrated to C++

It's interesting that Vitess is a thing then

https://vitess.io/docs/overview/history/

Keeping mysql over bigtable seems like a much bigger deal than the application layer being python vs c++/java/go.

"The front-end was Python..."

"The back-end was Python... ...."

okay.

Frontend at Google means something like an HTTP server, not a JavaScript app. Backend is e.g. your API server.

We do have a contradiction here, if that's what you're saying.

I was not in YT. I was only told their backend was Python by people who were. I can't explain that paper OP saw. Could be it reflected reality and I'm wrong; could be it was only a design.

I do know for a fact that they still had their own experiment infrastructure, which does suggest that the backend was still legacy.

I was also not in YT (was in Search from 09-14), but a bunch of my coworkers went over to work there around '10-11. I read the paper before joining Google; I think it came out in 07 or 08.

There might also be a lot of confusion over "backend" vs. "frontend" terminology. Like the other poster mentioned, "frontend" at Google usually means the webserver and sometimes extends back to various application-level services. Basically everything that involves user interaction. Experiment infrastructure has been part of the frontend in every system I've worked with at Google (which now includes Search, Google+, GFiber, Doodles, AndroidTV, and Assistant), though the flags often get plumbed back to backends to alter behavior there.

By "backend" I mean the storage & offline processing areas. BigTable, Colossus, MapReduce, various blob stores, training machine-learning models, etc. This is the part of YT that (in my understanding) was rewritten to use Google technologies.

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