Java TCP Sockets, best practice to reduce lag

Question

I'm currently creating a very simple Pong game in Java that is supposed to work over a network. I based the network design off a previous chat client-task I made earlier which consists of a server and a client. The clients connected to the server have separate threads waiting for them to send information to the server (clients are limited to 2 in the pong game obviously)

The way I designed the pong game is that all game logics are calculated on the server since it's such simple calculations and the data is saved in a PongData object that consists of 4 ints and one point (2 ints for players y-positions, 2 for the score and 1 point for the balls positions), this is then broadcasted to the 2 clients through a ObjectOutputStream and all the clients do is display it on the screen. Whenever they press a button on the client that is broadcasted through a DataOutputStream to the server.

When I run the game locally with a server and 2 clients it works perfectly but as soon as I run one of the clients on a separate computer it laggs very badly basically making the game unplayable. I'm unsure what the best practice to design games like these are, I've looked around stackoverflow and the internet and sending objects through UDP seems fairly complicated and most of all very unsafe but I'm not sure how to do it better through TCP without getting such a heavy lag.

Some additional information I can give is that the game loop thread carries out all the calculations, broadcasts the information and then sleeps for 10 ms before repeating it again which gives the game a good speed (locally at least).

Answer 1

Flush your streams, and call Socket.setTcpNoDelay(true) when creating the socket.