Load testing Facebook applications with random user databases

When we run load tests with FriendRunner, we’re doing it outside the realm of Facebook, so our users are not only virtual, they’re also fictional. They’re cooked up by a program we wrote to populate the user database we use when running tests.

We randomly threw together early versions of this database  since we were mostly concerned with sheer numbers of users. It wasn’t uncommon to have a 17 year old guy with 3 university degrees and a 58 year old wife. It was pretty random. But we found that some applications we’re testing query this kind of information, and they actually act on it enough to make a difference during a load test. This can cause problems, so we’ve had to go back and make the random generation process a little less random. And it’s made us feel, well, a little…

Omnipotent

That’s right – there’s a feeling of power associated with deciding the social rules of your little virtual and fictious world. For us, deciding on rules was easy – support what Facebook supports, and have fictional people reflect everyday society. Gay marriage? There’s no debate here, Facebook allows this and we do too. You won’t find many married same-sex couples in our database, but you’ll find some. Fourteen year old kids? In our world they can have girlfriends, but they can’t get married. Married people in the database live in the same city, are roughly the same age, and both partners have their Relationship status set to Married. In contrast to the real world, our fictional people don’t fight over things like this.

We do this so that any applications we test can query this information and act on it as realistically as possible. Which doesn’t mean there aren’t anomalies in the database. It’s possible to generate a user named Ahmed Goldstein who was born in Mississippi, and happens to be Catholic. But it’s hard to imagine how this would affect a load test.

Our improved algorithms for generating virtual users make it much easier for us to create custom user databases for you when necessary. If your app targets seniors, we’ll make all of your test users seniors. Writing an app for online dating? We can ensure that all of the users during the test are single.

Let us know how a custom user database could help you test your Facebook application.