Python Backend interview practice

Python service engineering: async correctness, typing, packaging, and performance — beyond syntax, into production judgment.

Topics this interview probes

Async/await correctness Type hints & mypy Packaging & deps GIL & parallelism FastAPI/Flask patterns Profiling

Your FastAPI endpoint mixes async database calls with CPU-bound work. Explain the failure mode and fixes.
When does the GIL actually matter, and how do you decide between threads, processes, and queues?
How would you bring an untyped legacy Python service to strict typing incrementally?

The live interviewer generates fresh, role-tailored questions — and drills down when your answers are vague.