Python · Senior · Theory

You have a FastAPI service, and under load the p99 latency climbs to seconds even though the CPU isn't busy. You suspect the event loop is being blocked. How would you find the cause and fix it?

~4 min by voice

How to approach it

The interviewer wants to see whether you understand the asyncio concurrency model: one synchronous call in an async def stalls the whole worker. It also matters that you can diagnose it with tools rather than guesswork, and pick the right fix for I/O versus CPU work.

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Topics

asyncio fastapi

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Answer by voice

The interviewer will ask this question and listen. Think out loud and ask for a hint if you need one. When you're done, pause or tap “That's my answer”. In about a minute, your score and the points you covered show up here.

Best with headphones · ~4 min