Lessons Learned from scaling Farmville

Lessons Learned from scaling Farmville

1.      Interactive games are write-heavy. Typical web apps read more than they write so many common architectures may not be sufficient. Read heavy apps can often get by with a caching layer in front of a single database. Write heavy apps will need to partition so writes are spread out and/or use an in-memory architecture.

2.    Design every component as a degradable service. Isolate components so increased latencies in one area won't ruin another. Throttle usage to help alleviate problems. Turn off features when necessary.

3.    Cache Facebook data. When you are deeply dependent on an external component consider caching that component's data to improve latency.

4.    Plan ahead for new release related usage spikes.

5.      Sample. When analyzing large streams of data, looking for problems for example, not every piece of data needs to be processed. Sampling data can yield the same results for much less work.

The key ideas are to isolate troubled and highly latent services from causing latency and performance issues elsewhere through use of error and timeout throttling, and if needed, disable functionality in the application using on/off switches and functionality based throttles.