You're seriously serving a billion requests a day? And you're writing new software which is expected to go from zero to a billion requests, full stop? And you're not expecting anything to change between beginning development and production? And, once the software is in production, it's not going to change at all?

I seriously doubt that all of those things are true - in which case you'd probably be better off using a different language. In my experience, it's much, much cheaper to run 2000 servers ($10m capital cost? something like that?) than double the number of software engineers you've got ($Xm a year, continuously?), and doubling the number of software engineers isn't a linear scaling.