Unexpected Behavior with TCP Socket Keep-Alive in Python 3.10
I'm reviewing some code and I'm implementing a TCP client-server application in Python 3.10, and I'm facing an issue with socket keep-alives. I expect that enabling keep-alives should help in maintaining a connection during periods of inactivity. However, it appears that the socket does not send keep-alive packets as expected. Here's how I'm setting up the server and client: **Server code:** ```python import socket server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM) server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) server_socket.bind(('localhost', 12345)) server_socket.listen(1) while True: conn, addr = server_socket.accept() print(f'Connected by {addr}') # Simulate some data processing conn.recv(1024) conn.close() ``` **Client code:** ```python import socket import time client_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM) client_socket.setsockopt(socket.IPPROTO_TCP, socket.TCP_KEEPALIVE, 1) client_socket.connect(('localhost', 12345)) # Simulate inactivity time.sleep(30) client_socket.sendall(b'Hello, Server!') client_socket.close() ``` I've added the keep-alive option on the client side using `socket.setsockopt()`, but I don't see any keep-alive packets when I monitor the connection with Wireshark. Instead, the connection times out after a defined inactivity period, which is not the behavior I expect. I’ve tried adjusting the TCP keep-alive interval by using `TCP_KEEPINTVL` and `TCP_KEEPIDLE`, but that also didn’t produce the desired effect. Could there be additional settings I need to configure on either the client or server side to ensure that keep-alives are functioning correctly? Is there something specific to Python's socket implementation or my OS (Linux) that may be causing this issue? Any feedback is welcome! I've been using Python for about a year now.