JMH generator: commemorative processor in the Java class library
JMH generator: commemorative processor in the Java class library
introduction:
In Java development, performance testing is one of the key steps to optimize code and evaluate application performance.JMH (Java Microbenchmark Harness) is a powerful performance testing tool in the Java class library that helps developers to write, run, and analyze the highly accurate benchmark test.This article will focus on the JMH generator and instance demonstration of using the annotation processor in the Java class library.
background knowledge:
Before talking about JMH, let's understand the background knowledge of performance testing.Performance testing is the process of evaluating the process of running speed, throughput, and resource utilization of the application under specific conditions.Under normal circumstances, we will use the benchmark test to compare the performance differences of different algorithms, different implementation or different hardware configuration.
JMH profile:
JMH is the official Java micro -foundation testing tool provided by Oracle.It allows developers to write highly reliable and accurate performance benchmark tests, and provide rich analysis tools to evaluate the test results.The JMH generator provides a set of annotated APIs to make the writing performance test simple and maintainable.It can eliminate many errors that are easy to occur in manual writing benchmark tests and provide accurate measurement results.
JMH generator example demonstration:
Below is a simple example demonstration, showing how to use the JMH generator and annotation processor to write and run the benchmark test.
1. Import jmh library:
First, we need to add the JMH library dependencies to the project.You can add the following dependencies in the project construction file (such as built.gradle or pom.xml):
// maven dependence
<dependency>
<groupId>org.openjdk.jmh</groupId>
<artifactId>jmh-core</artifactId>
<version>1.21</version>
</dependency>
<dependency>
<groupId>org.openjdk.jmh</groupId>
<artifactId>jmh-generator-annprocess</artifactId>
<version>1.21</version>
<scope>provided</scope>
</dependency>
2. Write the benchmark test:
Next, we need to write a benchmark test class.Add @benchmarkmode and @outputtimeunit to this class to set the benchmark test mode and time unit.Add @benchmark annotations to the method to specify methods that need to be performed for performance testing.
import org.openjdk.jmh.annotations.*;
import java.util.concurrent.TimeUnit;
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
public class MyBenchmark {
@Benchmark
public void testMethod() {
// Here is a way to test performance testing
}
}
3. Run the benchmark test:
After writing the base test class, we can use the JMH generator to run the benchmark test.The parameters and options of the following command line parameters configure the benchmark test:
java -jar jmh.jar -f 1 -i 5 -wi 5 -t 1 com.example.MyBenchmark
Among them, -F indicates the number of forks for the fork, -i represents the number of iterations, -wi represents the number of pre-heating iterations, and -t represents the number of threads.The final parameter specifies the benchmark test class to run.
Summarize:
The JMH generator is a very useful performance testing tool in Java development, which can help developers write, run, and analyze highly accurate benchmark tests.This article demonstrates how to use the JMH generator and annotation processor for performance testing through a simple example.By using the JMH generator, developers can better evaluate and optimize the performance of the code to improve the implementation efficiency of the application.
