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Misleading usage of asyncio.run() in code examples #348
Description
I'm relatively new to asyncio sooo maybe I use it in a wrong way.
Therefore maybe I call the methods wrongly.
My first goal was to just turn off an on the light and waiting 1 seconds in between those actions.
It works for the first bulb.set_brightness(0) call.
When I call bulb.set_brightness(100) it will set the brightness of my LB130 light bulb indeed to 100.
However the responds of the device raises a SmartDeviceException.
This is my current code:
from kasa import SmartBulb
import asyncio
import time
IP = "192.168.179.54"
bulb = SmartBulb(IP)
asyncio.run(bulb.update())
for i in range(10):
asyncio.run(bulb.set_brightness(0))
time.sleep(1)
asyncio.run(bulb.set_brightness(100))
time.sleep(1)The entire console output:
Traceback (most recent call last):
File "/home/lightbulb/.local/lib/python3.9/site-packages/kasa/protocol.py", line 156, in _query
return await asyncio.wait_for(
File "/usr/lib/python3.9/asyncio/tasks.py", line 481, in wait_for
return fut.result()
File "/home/lightbulb/.local/lib/python3.9/site-packages/kasa/protocol.py", line 94, in _execute_query
packed_block_size = await self.reader.readexactly(self.BLOCK_SIZE)
File "/usr/lib/python3.9/asyncio/streams.py", line 723, in readexactly
await self._wait_for_data('readexactly')
File "/usr/lib/python3.9/asyncio/streams.py", line 517, in _wait_for_data
await self._waiter
RuntimeError: Task <Task pending name='Task-13' coro=<TPLinkSmartHomeProtocol._execute_query() running at /home/lightbulb/.local/lib/python3.9/site-packages/kasa/protocol.py:94> cb=[_release_waiter(<Future pendi...x74cebe50>()]>)() at /usr/lib/python3.9/asyncio/tasks.py:416]> got Future <Future pending> attached to a different loop
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/home/lightbulb/.local/lib/python3.9/site-packages/kasa/smartdevice.py", line 254, in _query_helper
response = await self.protocol.query(request=request)
File "/home/lightbulb/.local/lib/python3.9/site-packages/kasa/protocol.py", line 73, in query
return await self._query(request, retry_count, timeout)
File "/home/lightbulb/.local/lib/python3.9/site-packages/kasa/protocol.py", line 160, in _query
await self.close()
File "/home/lightbulb/.local/lib/python3.9/site-packages/kasa/protocol.py", line 110, in close
writer.close()
File "/usr/lib/python3.9/asyncio/streams.py", line 353, in close
return self._transport.close()
File "/usr/lib/python3.9/asyncio/selector_events.py", line 700, in close
self._loop.call_soon(self._call_connection_lost, None)
File "/usr/lib/python3.9/asyncio/base_events.py", line 746, in call_soon
self._check_closed()
File "/usr/lib/python3.9/asyncio/base_events.py", line 510, in _check_closed
raise RuntimeError('Event loop is closed')
RuntimeError: Event loop is closed
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "/home/lightbulb/Desktop/scripts/kasa/kasa_light_control.py", line 15, in <module>
asyncio.run(bulb.set_brightness(i))
File "/usr/lib/python3.9/asyncio/runners.py", line 44, in run
return loop.run_until_complete(main)
File "/usr/lib/python3.9/asyncio/base_events.py", line 642, in run_until_complete
return future.result()
File "/home/lightbulb/.local/lib/python3.9/site-packages/kasa/smartdevice.py", line 77, in wrapped
return await f(*args, **kwargs)
File "/home/lightbulb/.local/lib/python3.9/site-packages/kasa/smartbulb.py", line 357, in set_brightness
return await self.set_light_state(light_state, transition=transition)
File "/home/lightbulb/.local/lib/python3.9/site-packages/kasa/smartbulb.py", line 233, in set_light_state
light_state = await self._query_helper(
File "/home/lightbulb/.local/lib/python3.9/site-packages/kasa/smartdevice.py", line 257, in _query_helper
raise SmartDeviceException(f"Communication error on {target}:{cmd}") from ex
kasa.exceptions.SmartDeviceException: Communication error on smartlife.iot.smartbulb.lightingservice:transition_light_state
Therefore the error gets thrown in the _query_helper function from the smartdevice.py module:
As mentioned above during the call of the brightness method I receive a responds that is perfectly fine.
However the second responds does not come through and raises the exception.
async def _query_helper(
self, target: str, cmd: str, arg: Optional[Dict] = None, child_ids=None
) -> Any:
"""Query device, return results or raise an exception.
:param target: Target system {system, time, emeter, ..}
:param cmd: Command to execute
:param arg: payload dict to be send to the device
:param child_ids: ids of child devices
:return: Unwrapped result for the call.
"""
request = self._create_request(target, cmd, arg, child_ids)
try:
response = await self.protocol.query(request=request)
except Exception as ex:
#print("oh no")
raise SmartDeviceException(f"Communication error on {target}:{cmd}") from ex
Activity
rytilahti commented on Jun 19, 2022
So this is happening as every asyncio.run() call creates a new event loop which then tries to re-use an already opened socket of another event loop causing it to crash. The first note on documentation (https://python-kasa.readthedocs.io/en/latest/smartdevice.html) and the examples that follow it instruct how to use it properly, while examples in the API documentation (e.g., https://python-kasa.readthedocs.io/en/latest/smartbulb.html#kasa.SmartBulb) are misleading. I will leave this issue open until the documentation gets updated to fix that.
For your specific use case, the simplest way to fix your issue is to move all device handling to happen inside a coroutine that gets executed using asyncio.run(), something like this:
from kasa import SmartBulb import asyncio IP = "192.168.179.54" bulb = SmartBulb(IP) async def loop_brightness(bulb): for i in range(10): await bulb.set_brightness(0) await asyncio.sleep(1) await bulb.set_brightness(100) await asyncio.sleep(1) asyncio.run(loop_brightness(bulb))Note the usage of await instead of asyncio.run(), and asyncio.sleep() instead of time.sleep().
timovr-dev commented on Jun 20, 2022
Thank you and you were right I was actually just looking at the light bulb documentation.
The code did not work entirely but it gave me the right idea therefore thank you so much!
This is the code that worked flawlessly:
rytilahti commented on Jun 20, 2022
Glad it is working for you now, I'll reopen this issue so that updating the docs doesn't get forgotten :-)
rytilahti commented on Jul 2, 2024
This should now be fixed by #968 and other recent PRs.