I would like to measure the coverage of my Python code which gets executed in the production system.
I want an answer to this question:

Which lines get executed often (hot spots) and which lines are never used (dead code)?

Of course this must not slow down my production site.
I am not talking about measuring the coverage of tests.
Maybe make a text file and through your every program method just append some text referenced to it like "Method one executed". Run the web application like 10 times thoroughly  as a viewer would and after this make a python program that reads the file and counts a specific parts of it or maybe even a pattern and adds it to a variable and outputs the variables.
How can I measure the coverage (in production system)?