Java Performance Tuning

Chapter 2. Profiling Tools

If you only have a hammer, you tend to see every problem as a nail.

—Abraham Maslow

Before you can tune your application, you need tools that will help you find the bottlenecks in the code. I have used many different tools for performance tuning, and so far I have found the commercially available profilers to be the most useful. You can easily find several of these, together with reviews of them, by searching the Web using java+optimi and java+profile, or checking the various computer magazines. These tools are usually available free for an evaluation period, and you can quickly tell which you prefer using. If your budget covers it, it is worth getting several profilers: they often have complementary features and provide different details about the running code. I have included a list of profilers in Chapter 15.

All profilers have some weaknesses, especially when you want to customize them to focus on particular aspects of the application. Another general problem with profilers is that they frequently fail to work in nonstandard environments. Nonstandard environments should be rare, considering Java’s emphasis on standardization, but most profiling tools work at the VM level, and the JVMPI ( Java Virtual Machine Profiler Interface) was only beginning to be standardized in JDK 1.2, so incompatibilities do occur. Even after the JVMPI standard is finalized, I expect there will be some nonstandard VMs you may have to use, possibly a specialized VM of some ...