Detected I/O inside the event loop

Hi What about this warning in the log? It’s my fault?

WARNING (MainThread) [homeassistant.util.async_] Detected I/O inside the event loop. This is causing stability issues. Please report issue to the custom component author for pyscript doing I/O at custom_components/pyscript/eval.py, line 1143: return func(*args, **kwargs) Thank you

[craigbarratt]

One more comment before I close this issue. If you need to do I/O from pyscript, the best solution is to find a package that is native async-based and use that. For example, instead of requests or urllib.request.urlopen, consider using aiohttp instead.

Looking at the client examples in aiohttp, you can fetch a URL with (there’s no need to include the await keyword; it is optional in pyscript):

import aiohttp

async with aiohttp.ClientSession() as session:
    async with session.get('https://raw.githubusercontent.com/custom-components/pyscript/master/README.md') as resp:
        print(resp.status)
        print(resp.text())

This is supported in the master code, but not the current release 0.21. So if you want to use async with you’ll need to run the master version instead of 0.21.

[craigbarratt]

I pushed a change 5908b4b that adds a new function, task.executor(). You can use that to call functions in packages that do I/O. task.executor() calls the function using run_in_executor(), which runs the function in a thread instead of the event loop.

Its arguments are the function to call, and the arguments that should be passed to that function. So instead of doing something like:

import requests

resp = requests.get('https://raw.githubusercontent.com/custom-components/pyscript/master/README.md')

you should do this instead:

import requests

resp = task.executor(requests.get, 'https://raw.githubusercontent.com/custom-components/pyscript/master/README.md')

There is no need to use task.executor() when the following code uses resp.text or resp.status_code since those don’t do I/O.

This is an experimental feature at this point. Please tell me if it fixes the warning you saw.