WhatsApp Server Serves Over One Million TCP Connections

The developers of the popular WhatsApp Messenger program reported on the blog that they had optimized the server backend to improve performance, uptime and scalability. As a result, they managed to achieve that one server serves more than a million tcp sessions. WhatsApp backend runs on FreeBSD + Erlang. They are not the first to achieve a million simultaneous tcp sessions on a single server.

$ netstat -an | grep -c EST
1016313