Detailed explanation

JMH (Java Microbenchmark Harness) is a tool for Java Micro -based testing for Java Microchasis.It can help developers evaluate and optimize the performance of their Java code.In JMH, Generators is a annotation processor for generating test data.This article will introduce the technical principles of the JMH Generators annotation processor. The JMH Generators annotation processor generates test data through the Java annotation mechanism.It can dynamically generate test data that meets the requirements according to the annotation information provided by developers.In JMH, there are three main annotation processors responsible for generating data:@state,@Param and @Setup.The principles of these three annotated processors are introduced below. @State is an annotation processor for marking the data state.It can be used to generate instances of test data and save it in the state object when JMH runtime.Developers can specify the number and type of test data that need to be generated in the @State annotation.For example, the following is an example of using @State annotation to generate test data: @State(Scope.Benchmark) public class MyBenchmark { @Param({"10", "100", "1000"}) private int size; private List<Integer> dataList; @Setup(Level.Iteration) public void setup() { dataList = new ArrayList<>(); // Generate test data according to size for (int i = 0; i < size; i++) { dataList.add(i); } } // Test code ... } In this example, the number of test data can be specified through the @Param annotation, and the test data can be generated through the @Setup annotation. @Param annotation processor is used to generate multiple sets of test data.Developers can specify the range of multiple sets of test data in the @Param annotation, and JMH will automatically pass these test data into the marked test method.For example: @Benchmark @Param({"1", "10", "100"}) public void myBenchmarkMethod(int size) { // Test code ... } In this example, the MybenchmarkMethod method will be executed three times, and the parameters 1, 10, and 100 will be passed as test data. @Setup annotation processor is used to generate the initialization method of test code.For example, you can specify a method in the @Setup annotation, and initialize the operation before each test.For example: @Benchmark @Setup(Level.Iteration) public void setup() { // Initialize operation } In this example, the Setup method is executed before each test iteration. In summary, the JMH Generators annotation processor generates test data through the Java annotation mechanism.It can dynamically generate test data that meets the requirements according to the annotation information provided by developers.These test data can be used to evaluate and optimize the performance of Java code.