Help - python filter script exited with status: 120

[fudoka]

I have a python3 script running in a filter.
If I run it using zmfilter.pl (as the web user) from the CLI it works perfectly Ok
If I Execute it within the Zoneminder filter editing screen it works perfectly Ok
When it runs as a background process it works but exits with status 120

The script uses ffmpeg to convert the event to a video file on a mounted partition and writes to a local log file. Checking the log file shows that the script has run without errors and exited with a return code zero.

Can anyone enlighten me as to just why I'm getting the exit status of 120 from zmfilter?

[fudoka]

Ok, after a fair amount of digging (i.e removing bits of the script bit by bit) I've found the culprit (I think)

The script uses the logging module
Removing the logging.StreamHandler handler seems to have done the trick
When running the script in a Zoneminder filter I now only have a logging.handlers.RotatingFileHandler handler and that seems to Ok