Java 17 JMH Benchmarking: Inconsistent Results with Different JVM Flags
I'm collaborating on a project where I'm working on a project and hit a roadblock. I'm trying to benchmark a method using JMH (Java Microbenchmark Harness) in Java 17, but I'm getting inconsistent results depending on the JVM flags I use. For instance, when I run my benchmark with the default settings, I get an average execution time of around 5ms, but when I enable the `-XX:+UseG1GC` flag, the average spikes to about 15ms. Here is my benchmark code: ```java import org.openjdk.jmh.annotations.*; import java.util.concurrent.TimeUnit; @BenchmarkMode(Mode.AverageTime) @OutputTimeUnit(TimeUnit.MILLISECONDS) @State(Scope.Thread) public class MyBenchmark { @Benchmark public void testMethod() { int sum = 0; for (int i = 0; i < 1000; i++) { sum += i; } } } ``` I tried running it with and without the `-jvmArgs "-XX:+UseG1GC"` option, and I'm using JMH version 1.36. The results are confusing as I expected the G1 garbage collector to improve performance due to its pause-time goals. I've also looked at the JMH documentation for configuration tips, but it doesn't mention anything about JVM flags leading to such drastic changes in performance. Is there something specific about the G1GC that could be affecting the execution time in this context? Am I missing best practices for running JMH benchmarks? Any insights or recommendations would be appreciated! My development environment is Linux. Any ideas what could be causing this? This is my first time working with Java 3.11. Any suggestions would be helpful. I'm coming from a different tech stack and learning Java. My development environment is macOS. I'm open to any suggestions. This is my first time working with Java 3.10. Thanks for your help in advance!