On 2023-01-26 7:16 PM, Dieter Maurer wrote:
Frank Millman wrote at 2023-1-26 12:12 +0200:
I have written a simple HTTP server using asyncio. It works, but I don't
always understand how it works, so I was pleased that Python 3.11
introduced some new high-level concepts that hide the gory details. I
want to refactor my code to use these concepts, but I am not finding it
easy.
In simple terms my main loop looked like this -
loop = asyncio.get_event_loop()
server = loop.run_until_complete(
asyncio.start_server(handle_client, host, port))
loop.run_until_complete(setup_companies())
session_check = asyncio.ensure_future(
check_sessions()) # start background task
print('Press Ctrl+C to stop')
try:
loop.run_forever()
except KeyboardInterrupt:
print()
finally:
session_check.cancel() # tell session_check to stop running
loop.run_until_complete(asyncio.wait([session_check]))
server.close()
loop.stop()
Why does your code uses several `loop.run*` calls?
In fact, I would define a single coroutine and run that
with `asyncio.run`.
This way, the coroutine can use all `asyncio` features,
including `loop.create_task`.
You are right, Dieter. The function that I showed above is a normal
function, not an async one. There was no particular reason for this - I
must have got it working like that at some point in the past, and 'if it
ain't broke ...'
I have changed it to async, which I call with 'asyncio.run'. It now
looks like this -
server = await asyncio.start_server(handle_client, host, port)
await setup_companies()
session_check = asyncio.create_task(
check_sessions()) # start background task
print('Press Ctrl+C to stop')
try:
await server.serve_forever()
except asyncio.CancelledError:
pass
finally:
session_check.cancel() # tell session_check to stop running
await asyncio.wait([session_check])
server.close()
It works exactly the same as before, and it is now much neater.
Thanks for the input.
Frank
--
https://mail.python.org/mailman/listinfo/python-list
