When a subclass of socketserver.BaseServer is running after calling serve_forever() and needs to be shutdown, it may be shut down by sending a [shutdown()](https://docs.python.org/3/library/socketserver.html#socketserver.BaseServer.shutdown). The thing is though that the shutdown() call must be run in a different thread than the one where the serve_forever() was called otherwise it will deadlock. This is documented in the [code](https://github.com/python/cpython/blob/3.8/Lib/socketserver.py#L244) but not in the documentation. It should be in the documentation as well as it is not obvious.