It relinquishes control for exactly one event loop cycle.

You'll see that it takes two or three cycles and then gets cancelled correctly.

The reason being is that recovery from your `await asyncio.sleep(1)` takes two or three cycles. (Under the hood, a few `asyncio.call_soon()` are called in a chain and only 1 is executed each cycle).

This is not a bug, but rather intended behavior. You should probably use `asyncio.to_thread()` or preferably run cpu-intensive code on a different process.

@triage Please close as not-a-bug.