Python · Mid-level · Theory

A FastAPI service started responding with delays of several seconds under load, even though the CPU is barely used. The endpoints are declared with async def. How would you find the cause?

~4 min by voice

How to approach it

This checks whether you understand the execution model of asyncio and FastAPI: low CPU with large delays is the classic sign of the event loop being blocked by a synchronous call inside async def, and it matters that you can confirm this with tools and fix it properly.

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asyncio debugging

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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.

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