DeprecationWarning: There is no current event loop

[wRAR]

/home/runner/work/scrapy/scrapy/scrapy/utils/reactor.py:70: DeprecationWarning: There is no current event loop
  event_loop = asyncio.get_event_loop()
tests/test_downloadermiddleware.py: 2 warnings
tests/test_utils_asyncgen.py: 2 warnings
tests/test_utils_defer.py: 4 warnings
tests/test_utils_python.py: 2 warnings
tests/test_utils_signal.py: 2 warnings
  /home/runner/work/scrapy/scrapy/scrapy/utils/defer.py:272: DeprecationWarning: There is no current event loop
    return Deferred.fromFuture(asyncio.ensure_future(o))
tests/test_utils_asyncio.py::AsyncioTest::test_install_asyncio_reactor
  /home/runner/work/scrapy/scrapy/scrapy/utils/reactor.py:70: DeprecationWarning: There is no current event loop
    event_loop = asyncio.get_event_loop()

Not sure yet what does this imply and when can this break (this is from tests on 3.10 and 3.11).

[wRAR]

asyncio.get_event_loop() now emits a deprecation warning if there is no running event loop. In the future it will be an alias of get_running_loop(). asyncio functions which implicitly create Future or Task objects now emit a deprecation warning if there is no running event loop and no explicit loop argument is passed

[shashwata27]

can I add an exception handling to this then? @wRAR

[wRAR]

@shashwata27 what kind of exception handling?

[Gallaecio]

Maybe we can just switch to get_running_loop(), it has been around since Python 3.7, which is our minimum Python version now.

I wonder, though, if there is any case where we can get a RuntimeError when using it. Looking at the deprecation warnings, they explicitly say that there is no running event loop, which would trigger a RuntimeError with get_running_loop().

[Gallaecio]

For:

scrapy/scrapy/utils/reactor.py

Line 70 in 82f25bc

event_loop = asyncio.get_event_loop()

A try-except like this may make sense:

try:
    event_loop = asyncio.get_running_loop()
except RuntimeError:
    event_loop = asyncio.new_event_loop()

[Gallaecio]

This seems problematic, though:

scrapy/scrapy/utils/defer.py

Line 323 in 52d9349

return d.asFuture(asyncio.get_event_loop())

[Gallaecio]

In the latter, maybe we could start by switching to get_running_loop(), and see what breaks. It should really only be called if there is a running loop, as far as I can tell. If not, maybe we are doing something wrong.