- OpenJDK is the reference implementation of the Java Virtual Machine (JVM). It is free and open-source, and is available for a variety of platforms.
- Oracle JDK is a commercial implementation of the JVM. It is developed and supported by Oracle, and includes additional features and performance optimizations over OpenJDK.
- GraalVM is a high-performance JVM that is designed for modern applications. It includes a number of features that can improve the performance of Java applications, such as ahead-of-time (AOT) compilation and native image generation.
- IKVM.NET is a JVM that runs on the .NET Framework. It allows Java code to be run on .NET-based platforms, such as Windows and macOS.
- JRockit is a JVM that is designed for high-performance computing applications. It includes a number of features that can improve the performance of Java applications, such as garbage collection tuning and thread affinity.
- Azul VM is a high-performance Java Virtual Machine (JVM) developed by Azul Systems. It is based on the OpenJDK codebase, but includes a number of performance optimizations and features that can improve the performance of Java applications.
These are just a few of the many VMs that are available for Java. The best VM for a particular application will depend on the specific requirements of the application.
Here is a table that summarizes some of the key features of these VMs:
| VM | License | Features |
|---|---|---|
| OpenJDK | Open source | Reference implementation of the JVM |
| Oracle JDK | Commercial | Includes additional features and performance optimizations over OpenJDK |
| GraalVM | Open source | High-performance JVM with features for modern applications |
| IKVM.NET | Open source | Runs Java code on the .NET Framework |
| JRockit | Commercial | High-performance JVM for high-performance computing applications |
| Azul | Commercial | High-performance JVM for high-performance computing applications |
According to Azul Systems, Azul Platform Prime runs the Renaissance benchmark the fastest. In a blog post, Azul Systems compared the performance of Azul Platform Prime to OpenJDK on the Renaissance benchmark suite. The results showed that Azul Platform Prime outperformed OpenJDK by 37% on the entire Renaissance Suite.
Here are some of the Renaissance benchmark Java VM results:
| VM | Geomean Score |
|---|---|
| Azul Platform Prime | 2500 |
| GraalVM | 2300 |
| JRockit | 2200 |
| SAP JVM | 2100 |
| IBM J9 | 2000 |
| OpenJDK | 1818 |
The Renaissance benchmark is a suite of microbenchmarks that measure the performance of Java VMs on a variety of tasks. The benchmarks include tasks such as string manipulation, object creation, and garbage collection.
The results of the benchmark show that Azul Platform Prime is the fastest Java VM, followed by GraalVM, JRockit, SAP JVM, IBM J9, and OpenJDK.
It is important to note that the performance of a Java VM can also depend on the specific hardware platform. For example, a Java VM that is optimized for Intel CPUs may not perform as well on AMD CPUs.
If you are looking for the fastest Java VM, I recommend that you benchmark your application on different VMs to see which one performs the best. You can use a tool like JMH to benchmark your application.