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uvloop may sleep less than n for asyncio.sleep(n) #739
Description
Bug Description
When calling asyncio.sleep, uvloop sometimes sleeps for fractionally less then the requested sleep time. E.g. await asyncio.sleep(0.1) -> Sleeps for 0.0991.
Expected behavior
Should always sleep for at least the specified time.
Environment
- Operating System:
Fedora 43 - Python Version:
Python 3.13.12 - uvloop Version:
0.22.1
Steps to Reproduce
Run the following script and observe output:
import asyncio
import statistics
import time
async def main():
sleep_times = []
for _ in range(100):
start_time = time.perf_counter()
await asyncio.sleep(0.1)
end_time = time.perf_counter()
sleep_times.append(end_time - start_time)
print(f"Min sleep time: {min(sleep_times):.4f} seconds")
print(f"Max sleep time: {max(sleep_times):.4f} seconds")
print(f"Average sleep time: {statistics.mean(sleep_times):.4f} seconds")
if __name__ == "__main__":
print("With default asyncio event loop:")
asyncio.run(main())
print("With uvloop event loop:")
import uvloop
asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())
asyncio.run(main())Output:
With default asyncio event loop:
Min sleep time: 0.1001 seconds
Max sleep time: 0.1008 seconds
Average sleep time: 0.1002 seconds
With uvloop event loop:
Min sleep time: 0.0991 seconds
Max sleep time: 0.1011 seconds
Average sleep time: 0.1001 seconds
Activity
Mark requeue test as xfail due to uvloop bug (#652)
Fix timers firing up to 1ms early