Chat reaches 1 billion messages sent per day

This post details reaching 1 billion messages per day for Facebook Chat. It describes specific engineering improvements made to handle this scale, including increasing load balancer capacity, investigating backend/frontend robustness against failures, and optimizing channel servers. A key technical detail is the reduction of memory load by explicitly discarding unused HTTP request headers (cookies and other headers) after they are no longer needed for response construction, which frees up memory to serve more users per machine.