On many occasions, Java applications may suffer from performance degradation. Exacerbating the issue is a lack of performance tests that can provide at least a minimal set of guarantees that performance requirements are met and, moreover, the performance of certain features will not degrade over time. Measuring the performance of Java applications is not trivial, especially due to the fact that there are a number of compiler and runtime optimizations that may affect performance statistics. For that reason, additional measures, such as warm-up phases and other tricks, must be used in order to provide more accurate performance measurements. The JMH is a framework that incorporates a number of techniques, along with a convenient API that can be used for this purpose. It is not a new tool but was included with the distribution of Java 9. If you have not added JMH to your toolbox yet, read Chapter 8, Microbenchmarking Applications with JMH, to learn about the use of JMH in the context of Java application development.