DomainSponsor is Oversee’s domain parking division. When people have domain names that they’re not ready to use yet, we show ads on them. DomainSponsor gets around a billion visits per month.
To serve ads on millions of pages per day, we used to use a fairly traditional LAMP stack. We used Apache with mod_perl to run a fairly complicated tangle of Perl code which queried several back-end MySQL databases and other back-end servers, in order to choose what to put on each page. One of the biggest problems we had was that we wanted to be able to easily add new (possibly buggy) features for A/B testing, knowing that many of those features would fail and be discarded. The old way we did this was to have a separate cluster of servers running the test version of the code. The trouble was that the test cluster was never 100% identical to the main production cluster, and the redirect needed to send a sample of requests to the test cluster introduced a delay, so we had problems with test results not being reproducible when we later launched the same feature in the main production cluster. [Read more...]