A preliminary phone interview, followed by a large task about creating a large scale data processing pipeline that they want you to complete in a 2--3 hour pipeline. (Map-Reduce of a CSV row counter) They revealed AFTERWARDS that they wanted this data pipeline to work at scale, not just to throw a draft and then explain how you could scale it. After spending many hours doing a task, they don't even ask you about the architecture, just asking irrelevant question, like, "do you know what the GIL is in python" and focusing dead on on this topic, that I am pretty sure they misunderstood themselves how it works (I think due to a misunderstanding on how async/await task work in python, I think the interviewers are unaware that C extension code can span threads that don't lock the GIL, especially if these threads are just waiting in I/O the GIL doesn't cause any issues)