Why are you starting 4 process when you only need one running?

Eh, it's my fault. I didn't make the problem clear enough. I suppose there are 4 process working, apscheduler and flask work in the same process(the specific one of four process) and the other three are pure flask process.
the question is the same as question on StackOverFlow

Now my partner and i try to solve this problem by using 4 process running flask application and 1 process running flask and apscheduler to manage the period task of flask application.

Sorry for my poor English T^T , if you have good solution please tell me. Thank you honestly！

The only reason I see to spawn more process is because your Flask app is growing, so I do recommend to split up your project, one only for scheduling and another one for the Flask app.

Another solution would be running one process for the Flask APScheduler using one port (e.g 5001) and running 4 process for the Flask App using another port (e.g 5000), it seems you are trying to do it.

Ok👌. Thank you for your advice sincerely, that's helpful, also thanks for the flask-apscheduler, that's great.