practice

Doi: 10.1145/1378704.1378716

Online games and virtual worlds have familiar scaling requirements, but don’t be fooled: Everything you know is wrong.

By Jim WaLDo
scaling
in Games
and Virtual
Worlds

I USED TO be like you.

I used to be a systems programmer, working on infrastructure used by banks, telecom companies, and other engineers. I worked on operating systems. I worked on distributed middleware. I worked on programming languages. I wrote tools. I did all of the things that hardcore systems programmers do.

And I knew the rules. I knew that throughput was the real test of scaling. I knew that data had to be kept consistent and durable, and that relational databases are the way to ensure atomicity, and that loss of information is never an option. I knew that clients were getting thinner as the layers of servers increased, and that the best client would be one that contained the least amount of state and allowed the important computations to go on inside the computing cloud. I knew that support for legacy code is vital to the

adoption of any new technology, and that most legacy code has yet to be written.

But two years ago my world changed. I was asked to take on the technical architect position on Project Darkstar, a distributed infrastructure targeted to the massive-multiplayer online game and virtual-world market. At first, it seemed like a familiar system. The goal was to scale flexibly by enabling the dynamic addition (or subtraction) of machines to match load. There was a persistence layer and a communication layer. We also wanted to make the programming model as simple as possible, while enabling the system to use all the power of the new generations of multicore chips that Sun (and others) were producing. These were all problems that I had encountered before, so how hard could these particular versions of the problems for this particular market be? I agreed to spend a couple of months on the project, cleaning up the architecture and making sure it was on the right track while I thought about new research topics that I might want to tackle.

The three months have turned into two years (and counting). I’ve found lots of new research challenges, but they all have to do with finding ways to make the environment for online games and virtual worlds scale. In the process, I have been introduced to a different world of computing, with different problems, different assumptions, and a different environment. At times I feel like an anthropologist who has discovered a new civilization. I’m still learning about the culture and practice of games, and it is a different world.

 

everything you Know is Wrong To understand this new world, the first thing to realize is that it is part of the entertainment industry. Because of this, the most important goal for a game or virtual world is that it be fun. Everything else is secondary to this prime directive. Being fun is not an objective measure, but the goal is to provide an immersive, all-consuming experience

ILLUSTRATION BY PETER GOLIBERSUCH