Chapter 42

Optimization is one of the most enjoyable parts of software design, but unfortunately it does not claim a high percentage of development time. Generally speaking, it is not a task to consider until the time spent is justified, which is often toward the end of the development cycle (but not always!) Still, it is an important step, especially with products like LiveWhale, which has to perform well under high traffic spikes. I’ve already talked about general page caching before, but fine-tuning a PHP application for speed when something is not cached is also important. Here are some thoughts on how to do just that.

At the code level, LiveWhale is a framework, which means the same codebase is hit for many different types of requests. The question is then: how to achieve high performance with a codebase that has to perform so many tasks and is therefore code heavy. It makes sense to divide code across a handful of files. The objective here is to only load libraries when you need them. A typical request will only use a tiny percentage of the entire codebase, so there’s no need to read a great deal of code from the filesystem and eat up RAM per PHP request. Also, with a modular system like LiveWhale, it is not explicitly known what modules exist that will need to be loaded. An important optimization is one where only the first request to the server has to perform logic to determine what to load. The results of this expensive operation are cached, and all subsequent LiveWhale requests enjoy dramatic savings in the module loader. Read more »