JMH generator: Introduction to the annotation processor in the Java class library
JMH generator: Introduction to the annotation processor in the Java class library
Summary: The JMH generator is the abbreviation of Java Microbenchmark Harness. It is a powerful benchmark testing tool to measure the performance of the Java application.This article will introduce the basic concepts, usage methods and example code of the JMH generator.
Overview:
The JMH generator is an open source Java class library, which is widely used in the field of Java development.It provides a set of annotations and APIs for writing and running benchmark tests.By using the JMH generator, developers can easily create accurate, repeated and reliable performance tests in order to compare and evaluate the performance differences of different code implementation.
The JMH generator is based on the Annotion Processor in the Java language specification. It can scan and analyze the source code with a specific annotation during compilation to generate the performance testing program.This allows developers to use the powerful function of the JMH generator without manually writing a tedious test code.
How to use:
To use the JMH generator, first of all, you need to introduce the dependencies of this type of library in the construction configuration of the project.Generally speaking, in the Maven project, the following dependencies can be added to the pom.xml file:
<dependency>
<groupId>org.openjdk.jmh</groupId>
<artifactId>jmh-core</artifactId>
<version>1.27</version>
<scope>test</scope>
</dependency>
After introducing dependencies, you can start writing performance test code.First, add @benchmark annotations to the test to be tested, indicating that this method is a performance test case.You can then use the @Setup annotation to perform some initialization operations, such as creating a data structure or connecting to the database.Finally, use@FORK,@Warmup and @MeaSurement annotations to configure the test parameters, such as the number of tests, preheating times, etc.Code examples are as follows:
import org.openjdk.jmh.annotations.*;
@State(Scope.Thread)
public class MyBenchmark {
private MyData data;
@Setup
public void setup() {
// Initialize operation
data = new MyData();
}
@Benchmark
@Fork(1)
@Warmup(iterations = 5)
@Measurement(iterations = 10)
public void myBenchmark() {
// Method to be tested
data.process();
}
}
The above code uses the JMH generator to create a simple benchmark test.Among them, @State annotations indicate that the instances of this class will be shared during the test.@Setup annotations are used to perform initialization operations.@Benchmark annotation indicates the method to be tested.
Running performance test:
After completing the performance test code, you can use the corresponding tools provided by JMH for testing and data collection.You can run the benchmark test below:
import org.openjdk.jmh.runner.Runner;
import org.openjdk.jmh.runner.RunnerException;
import org.openjdk.jmh.runner.options.Options;
import org.openjdk.jmh.runner.options.OptionsBuilder;
public class TestRunner {
public static void main(String[] args) throws RunnerException {
Options options = new OptionsBuilder()
.include(MyBenchmark.class.getSimpleName())
.build();
new Runner(options).run();
}
}
The above code creates a Testrunner class that builds a test configuration parameter through OptionsBuilder, and passes the reference name name to be tested as the parameter to Options Include method.The main method of running Testrunner can start the performance test.
Summarize:
This article introduces the basic concepts, usage methods and example code of the JMH generator.The JMH generator is a powerful benchmark testing tool that can help developers accurately and reliably evaluate the performance of the Java application.By using the JMH generator, developers can easily test performance and optimize the application.
references:
-Epenjdk jmh official website: https://openjdk.java.net/projects/code-tools/jmh///
-Jmh github warehouse: https://github.com/openjdk/jmh
