The point is that it's still shared state, so it's possible in practice to take down your server if you manage to corrupt your database or a file on your filesy

The point is that it's still shared state, so it's possible in practice to take down your server if you manage to corrupt your database or a file on your filesystem. About the only thing you're protected against is memory leaks, and that seems to be because you have to, otherwise PHP would fall over in a big heap: https://www.google.com/search?q=php+memory+leak https://www.google.com/search?q=php+memory+leak I haven't had any problems with memory leaks running things like Django or Bottle.