Python [Errno 98] Address already in use

Yes, it is intended. Here you can read detailed explanation. It is possible to override this behavior by setting SO_REUSEADDR option on a socket. For example:

sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

$ ps -fA | grep python
501 81211 12368   0  10:11PM ttys000    0:03.12  
python -m SimpleHTTPServer

$ kill 81211

This happens because you trying to run service at the same port and there is an already running application. it can happen because your service is not stopped in the process stack. you just have to kill those processes.

There is no need to install anything here is the one line command to kill all running python processes.

for Linux based OS:

Bash:

kill -9 $(ps -A | grep python | awk '{print $1}')

Fish:

kill -9 (ps -A | grep python | awk '{print $1}')

If you use a TCPServer, UDPServer or their subclasses in the socketserver module, you can set this class variable (before instantiating a server):

socketserver.TCPServer.allow_reuse_address = True

(via SocketServer.ThreadingTCPServer - Cannot bind to address after program restart )

This causes the init (constructor) to:

 if self.allow_reuse_address:
     self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)