Concurrency is a topic that isn't often considered by Drupal module developers, because it doesn't affect "typical" Drupal applications such as blogs. But when it matters, it can't be ignored.

This talk will discuss the nature of concurrency in Drupal, including when, where and how it can cause problems and what can be done to avoid those problems. Specifically, I will focus on concurrency in e-commerce applications, where failure to ensure correctness in a multi-user environment has monetary and legal implications.

No prior knowledge of concurrent programming techniques will be assumed, but the material presented will be heavy on code samples to illustrate the problems and solutions.