Flask global variables and sessions
Generally speaking, global variables are shared between requests.
Some WSGI servers can use a new separate process for each request, but that is not an efficient way to scale your requests. Most will use treading or several child processes to spread the load but even in the case of separate child processes each subprocess will have to handle multiple requests during its lifetime.
In other words: no, Flask will not protect your global variables from being shared between different users.
If I have global variables in flask and have multiple users accessing the site at once, can one persons session overwrite the global variables of another persons session, or does flask make a unique instance of my site and program code each time its requested from a users browser?