Java Performance, 2nd Edition

Preface

When O’Reilly first approached me about writing a book on Java performance tuning, I was unsure. Java performance, I thought—aren’t we done with that? Yes, I still work on improving the performance of Java (and other) applications on a daily basis, but I like to think that I spend most of my time dealing with algorithmic inefficiencies and external system bottlenecks rather than on anything directly related to Java tuning.

A moment’s reflection convinced me that I was (as usual) kidding myself. It is certainly true that end-to-end system performance takes up a lot of my time, and that I sometimes come across code that uses an $O\left(n^2\right)$ algorithm when it could use one with O(logN) performance. Still, it turns out that every day I think about garbage collection (GC) performance, or the performance of the JVM compiler, or how to get the best performance from Java APIs.

That is not to minimize the enormous progress that has been made in the performance of Java and JVMs over the past 20-plus years. When I was a Java evangelist at Sun during the late 1990s, the only real “benchmark” available was CaffeineMark 2.0 from Pendragon software. For a variety of reasons, the design of that benchmark quickly limited its value; yet in its day, we were fond of telling everyone that Java 1.1.8 performance was eight times faster than Java 1.0 performance based on that benchmark. And that was true—Java 1.1.8 had an actual just-in-time compiler, whereas Java 1.0 was pretty much completely ...