Filters & Triggers => "Activate Preview" feature not working

[Dodutils]

Describe the bug
Activate Preview feature do not work and generate Pyhton error (copy added at the end of this message) it seems that some socket is used for a second usage with same network parameters which is not allowed.

=> "OSError: [WinError 10048] Une seule utilisation de chaque adresse de socket (protocole/adresse réseau/port) est habituellement autorisée" once translated in english it is "Only one instance of each socket address (protocol/network address/port) is usually authorized".

Then changedetection do not work anymore and you must kill and restart restart changedetection.py

Version
0.48.01

How did you install?
PIP3 Windows / Python 3.13 used

To Reproduce

Steps to reproduce the behavior:

1. Go to 'Filters & Triggers' for any web site you have
2. Click on 'Activate Preview'
3. 'Loading...' will appear but that's it
4. Error appear in the Pyhton console

! ALWAYS INCLUDE AN EXAMPLE URL WHERE IT IS POSSIBLE TO RE-CREATE THE ISSUE - USE THE 'SHARE WATCH' FEATURE AND PASTE IN THE SHARE-LINK!

Expected behavior
Should show the preview isn't it ?

Screenshots
No really needed

Desktop (please complete the following information):

• OS: Windows 10
• Browser Chrome
• Version 131

Additional context
Python traceback error output :

Traceback (most recent call last):
File "", line 1, in
from multiprocessing.spawn import spawn_main; spawn_main(parent_pid=5608, pipe_handle=1352)
~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\xxx\AppData\Local\Programs\Python\Python313\Lib\multiprocessing\spawn.py", line 122, in spawn_main
exitcode = _main(fd, parent_sentinel)
File "", line 1, in
from multiprocessing.spawn import spawn_main; spawn_main(parent_pid=5608, pipe_handle=1344)
~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\xxx\AppData\Local\Programs\Python\Python313\Lib\multiprocessing\spawn.py", line 131, in _main
prepare(preparation_data)
~~~~~~~^^^^^^^^^^^^^^^^^^
File "C:\Users\xxx\AppData\Local\Programs\Python\Python313\Lib\multiprocessing\spawn.py", line 122, in spawn_main
exitcode = _main(fd, parent_sentinel)
File "C:\Users\xxx\AppData\Local\Programs\Python\Python313\Lib\multiprocessing\spawn.py", line 131, in _main
prepare(preparation_data)
~~~~~~~^^^^^^^^^^^^^^^^^^
File "C:\Users\xxx\AppData\Local\Programs\Python\Python313\Lib\multiprocessing\spawn.py", line 246, in prepare
_fixup_main_from_path(data['init_main_from_path'])
~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\xxx\AppData\Local\Programs\Python\Python313\Lib\multiprocessing\spawn.py", line 246, in prepare
_fixup_main_from_path(data['init_main_from_path'])
~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\xxx\AppData\Local\Programs\Python\Python313\Lib\multiprocessing\spawn.py", line 297, in _fixup_main_from_path
main_content = runpy.run_path(main_path,
run_name="mp_main")
File "", line 287, in run_path
File "", line 98, in _run_module_code
File "C:\Users\xxx\AppData\Local\Programs\Python\Python313\Lib\multiprocessing\spawn.py", line 297, in _fixup_main_from_path
main_content = runpy.run_path(main_path,
run_name="mp_main")
File "", line 88, in _run_code
File "", line 287, in run_path
File "C:\Perso\Internet\changedetection.io\changedetection.py", line 6, in
changedetectionio.main()
~~~~~~~~~~~~~~~~~~~~~~^^
File "", line 98, in run_module_code
File "", line 88, in run_code
File "C:\Perso\Internet\changedetection.io\changedetectionio_init.py", line 193, in main
eventlet.wsgi.server(eventlet.listen((host, int(port)), s_type), app)
~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Perso\Internet\changedetection.io\changedetection.py", line 6, in
changedetectionio.main()
~~~~~~~~~~~~~~~~~~~~~~^^
File "C:\Perso\Internet\changedetection.io\changedetectionio_init.py", line 193, in main
eventlet.wsgi.server(eventlet.listen((host, int(port)), s_type), app)
~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\xxx\AppData\Local\Programs\Python\Python313\Lib\site-packages\eventlet\convenience.py", line 78, in listen
sock.bind(addr)
~~~~~~~~~^^^^^^
OSError: [WinError 10048] Une seule utilisation de chaque adresse de socket (protocole/adresse réseau/port) est habituellement autorisée
File "C:\Users\xxx\AppData\Local\Programs\Python\Python313\Lib\site-packages\eventlet\convenience.py", line 78, in listen
sock.bind(addr)
~~~~~~~~~^^^^^^
OSError: [WinError 10048] Une seule utilisation de chaque adresse de socket (protocole/adresse réseau/port) est habituellement autorisée

[nicoell]

#!/usr/bin/env python3

# Only exists for direct CLI usage

if __name__ == "__main__":
    import changedetectionio
    changedetectionio.main()

Adding if __name__ == "__main__": to changedetection.py seems to solve the issue. I'm not too proficient with python, so not sure if that is intended way of fixing it.

[dgtlmoon]

@nicoell none of this should be necessary, it is afterall just another flask query route in the application..

does the app start and run properly anyway?

[nicoell]

I only experienced this when running or debugging changedetection.io via changedetection.py within the IDE (PyCharm).
Without the name code above the app runs and works until some multiprocess thingy starts (e.g. when activating preview) at which point the above errors occur (plus some others, like json file being written to already).
With the name code, this error does not happen.

When running from command line, I couldn't reproduce. Not sure what's different when run from PyCharm IDE.

[dgtlmoon]

changedetectionio_init.py ... you are writing some weird custom code, this is not a file in our codebase...