Logfiles are not rotated on Windows

[schooft]

This might not be easy to solve due to https://bugs.python.org/issue4749

Don't use RotatingFileHandler in any process which spawns a subprocess. In a multiprocess situation where you want to use rotating log files, have a dedicated subprocess (which does not spawn any children) which listens for logging events on a socket and writes them to the rotated log. Have every other process use SocketHandler to log events to the aforementioned dedicated process. There is an example in the Python documentation of listening for events on a socket.