Optimizing Java

Chapter 1. Optimization and Performance Defined

Optimizing the performance of Java (or any other sort of code) is often seen as a Dark Art. There’s a mystique about performance analysis—it’s commonly viewed as a craft practiced by the “lone hacker, who is tortured and deep thinking” (one of Hollywood’s favorite tropes about computers and the people who operate them). The image is one of a single individual who can see deeply into a system and come up with a magic solution that makes the system work faster.

This image is often coupled with the unfortunate (but all-too-common) situation where performance is a second-class concern of the software teams. This sets up a scenario where analysis is only done once the system is already in trouble, and so needs a performance “hero” to save it. The reality, however, is a little different.

The truth is that performance analysis is a weird blend of hard empiricism and squishy human psychology. What matters is, at one and the same time, the absolute numbers of observable metrics and how the end users and stakeholders feel about them. The resolution of this apparent paradox is the subject of the rest of this book.

Java Performance—The Wrong Way

For many years, one of the top three hits on Google for “Java performance tuning” was an article from 1997–8, which had been ingested into the index very early in Google’s history. The page had presumably stayed close to the top because its initial ranking served to actively drive traffic to it, creating ...