Server side python code runing continuosly per session
Celery is a great solution, but it can be overpowered for many setups. If you just need tasks to run periodically (once an hour, once a day, etc) then consider just using cron. 
There's a lot less setup and it can get you quite far.
I have searched the forums for my question but im either searching for a thing naming it wrongly or the question is hard which i really doubt.
I am developing a web-app which would have an web-interface written in one of the MVC frameworks like django or even flask and allow user to login, will identify users session and allow to make some settings and also my app needs to run some python process(script which basically is a separate file) on the server on a per-session per-settings made by user basis. This process is quite long - can take even days to perform and shouldn't affect the execution and performance of MVC part of an app. Another issue is that this process should be run per user so the basic usage model of such app would be:
1. the user enters the site.
2. the user makes some settings which are mirrored to database.
3. the user pushes the launch button which executes some python script just for this user with the settings he has made.
4. the user is able to monitor some parameters of the script running based on some messages that the script itself generates.
I do understand that my question is related to the architecture of the app itself and i'm quite new to python and haven't had any experience of developing such complex application but I'm also quite eager to learn about it. I do understand the bricks from which my app should be built (like django or flask and the server-side script itself) but i know very little about how this elements should be glued together to create seamless environment. Please direct me to some articles related to this topic or recommend some similar threads or just give a clear high level explanation how such separate python processes could be triggered,run and monitored further on a per-user basis from controller part of MVC.