Closed
Description
I know this behavior has been reported before, but I am still seeing it. Tracking a strange condition in our software, where cancelling a task soon after creating it did not work, we found the issue in wait_for and some other reported issues, the last one being #7386
I also found this reported in Python, and a test program mentioned there causes also the issue on micropython : https://bugs.python.org/issue42130
Basically, this code :
import uasyncio as asyncio
async def inner():
return
async def with_for_coro():
await asyncio.wait_for(inner(), timeout=100)
await asyncio.sleep(1)
print('End of with_for_coro. Should not be reached!')
async def main():
task = asyncio.create_task(with_for_coro())
await asyncio.sleep(0)
assert not task.done()
task.cancel()
print('Called task.cancel()')
await task # -> You would expect a CancelledError to be raised.
asyncio.run(main())Running this, no CancelledError is raised when awaiting task in main() and we get this output:
$ micropython cancel.py
Called task.cancel()
End of with_for_coro. Should not be reached!
Now, if we add a small delay before cancelling, changing for instance to 0.1s:
async def main():
task = asyncio.create_task(with_for_coro())
await asyncio.sleep(0.1)Then we get the expect result :
$ micropython cancel.py
Called task.cancel()
Traceback (most recent call last):
File "cancel.py", line 21, in <module>
File "/usr/lib/micropython/uasyncio/core.py", line 222, in run
File "/usr/lib/micropython/uasyncio/core.py", line 191, in run_until_complete
File "/usr/lib/micropython/uasyncio/core.py", line 176, in run_until_complete
File "cancel.py", line 18, in main
File "/usr/lib/micropython/uasyncio/task.py", line 145, in __next__
File "/usr/lib/micropython/uasyncio/core.py", line 183, in run_until_complete
File "cancel.py", line 9, in with_for_coro
CancelledError:
This was tested using micropython 1.18