Flask seems to launch 2 instances of python [duplicate]

Question

I have several Flask applications, but they all seem to launch 2 instances of Python. I have no idea why.

Edit: I have googled for Flask and multiple instances of Python, etc, but not one of my searches led me to the 'already answered question' here. I find my question much more to the point than: "Why does running the Flask dev server runs itself twice?" Huh? What is the Flask dev server? Does it have anything to do with Python running twice?

Answer 1

It happens because you run your Flask applications in debug mode:

app.run(host='0.0.0.0', debug=True)

Debug mode automatically reloads the source files when they change. This is implemented so that Flask (actually, Werkzeug, a library used by Flask) spawns another Python interpreter, which monitors the source files and restarts the other interpreter that is running your Flask app.

If you set debug=False, you should get only one instance of Python per Flask app.