At Source, the Trib’s Travis Swicegood tells the tale:
Before the night was over we had over 15,000 concurrent users on texastribune.org and more than 183,000 people watching our YouTube live stream on various places around the net as the proceedings wound down shortly after midnight local time (we peaked at 12:03, as the final votes were cast too late).
We handled all of this traffic with no downtime and no additional servers.
The main credit goes to Varnish, a sort of super-charged version of the caching plugins WordPress users will be familiar with, which lets parts of the Trib’s site be served from memory rather than disk.
Protect your application servers. The bottom line is that you can’t handle massive volumes of scale and serve all of your content dynamically all of the time. You don’t have to strip your site down, either, just use what’s available to you. Use Varnish to protect your app servers and make sure that they don’t get slammed. Use external services for the really hard parts so you don’t have to worry about that.
— Joshua Benton