Today was a great day, we have been able to fix the bugs which didn't allow us to run a bigger number of clients. After that we have tested to run more and more clients. At the end of the day we were able to run ca. 3000 clients and they all played pong with each other, we had too one normal player who played against a bot.
We had a look at the load of the computer which run the server and it was not really stressed but only up at a load of ca. 0.31. The problem seemed to be the network we have been working on, it was a ad-hock WLAN network between all our laptops which isn't the fastest. And since we use TCP which resends all the data packages which got lost we got quite a big amount of traffic and therefore a high round trip time ("lag" in game speek).
For the future we want to try to get a GB-network-switch and attach our computers via cable. It's a pitty that we will not have the time to implement UDP to get it working with lower lag.
Another bottleneck was running all the bots, which are written in ruby (and each bot is a real process), on our limited amount of laptops (we had only 3). Jonatan was able to start ca. 2500 on his linux machine but I, on OS X, was only able to start ca. 200, after that it said I was not allowed to start more processes. Therefore, before we will be able to do some real statistic stuff, we will implement the bots in erlang, processes there are cheap.
But it was a great feeling to see 1500 games of pong, it is indeed a real time game, running on our GGS-prototype without having performance problems other then the network-bottleneck.