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asyncio.sleep(float('nan')) does not raise ValueError #105331
Description
Bug report
time.sleep(float('nan')) raises ValueError, but asyncio.sleep(float('nan')) is valid and sleeps for 0. This seems bad, and asyncio.sleep should probably also raise ValueError.
import asyncio
import time
try:
time.sleep(float('nan'))
except ValueError:
print("time.sleep raised ValueError")
async def foo() -> None:
await asyncio.sleep(float('nan'))
print("asyncio.sleep does not raise any error")
asyncio.run(foo())$ python foo.py
time.sleep raised ValueError
asyncio.sleep does not raise any errortime.sleep and asyncio.sleep do differ in behaviour when it comes to negative numbers and changing that behaviour was considered a breaking change without strong reason: #83879
nan feels like it should very rare to be passed intentionally, but the potential gain might also be small enough that this isn't worth fixing.
Related: python-trio/trio#2493
Your environment
- CPython versions tested on: 3.8 to 3.11
- Operating system and architecture:
Linux 6.3.4-arch1-1
Activity
sobolevn commentedon Jun 6, 2023
It is also different for negative values.
For example:
and
jakkdl commentedon Jun 6, 2023
Yes, I wrote
kumaraditya303 commentedon Jun 9, 2023
I don't think we should change it at this point, I can accept a docs improvement for this but I'm -1 on changing the behavior.
Zac-HD commentedon Jun 9, 2023
fwiw I'd expect it to follow whatever
time.sleep()does with weird arguments, and think that there's a pretty strong argument in favor of consistency.gvanrossum commentedon Jun 10, 2023
Hm, I expect at this point there is probably plenty of working code out there that passes a negative delay to
asyncio.sleep(perhaps the result of trying to sleep until some target time that's slightly in the past).I don't see how NaN could be the result of such a computation, so I agree NaN is a "weird" argument (and leads to undefined behavior).
So I think I can only approve of the NaN check.
pythongh-105331: Fix asyncio.sleep() bug
pythongh-105331: move import math to the toplevel
pythongh-105331: Improve the content description of the error message
pythongh-105331: Improve description to more detailed
pythongh-105331: Improve description to more detailed
pythongh-105331: Improve description to more detailed
pythongh-105331: Fix the indentation change
pythongh-105331: Add test for asyncio.sleep() delay is nan
pythongh-105331: Move check delay is nan section after delay <= 0 sec…
pythongh-105331: Add description for versionchanged
gh-105331: Change `asyncio.sleep` to raise ``ValueError` for nan (#10…
Merge branch 'main' into modulelocals