For many legacy Java applications (e.g. using Java 8), upgrading the application to higher version of JDK often requires costly and time-consuming project migration.
CompoundVM (CVM) is a project that aims to bring higher version JVM performance to lower version JDK. Now you can run your application with advanced JVM features with almost zero cost to upgrade your project.
The current release is 8.0.0, which enables JVM 17 on JDK 8. We aim to keep up with the latest JVM. CVM has been used by a number of services in production environment. The current release supports linux/x86_64 platform only.
CVM is developed under the same licence as the upstream OpenJDK project.
Higher version of JVM brings enhancements in garbage colleciton, JIT, etc.
- Enhanced ParallelGC and G1GC, next generation ZGC, with higher throughput, lower latency, and less memory footprints
- Enhanced JIT compiler, support more intrinsics with faster implementation
- Drop-in replacement for existing JDK, easy to upgrade and rollback
CVM has been throughly tested on various application scenarios, including Java Microbenchmark Harness (JMH), SPECjbb2015, Flink nexmark, etc. Compared to jdk8u372, some of the performance results are as follows:
| Application | Performance Improvement |
|---|---|
| JMH java.util all cases average | 30% |
| JMH java.util.stream all cases average | 45% |
| SPECjbb2015 critical-jOPS | 90% |
| SPECjbb2015 max-jOPS | 5% |
| Flink nexmark all queries average | 10% |
You may download a pre-built CVM from its release page, and uncompress the package to your destination directory.
You can build CVM from source, by running the following command:
make -f cvm.mk cvm8default17
For more options run make -f cvm.mk help
After CVM is installed, command ${CVM_DIR}/bin/java -version will show the following output:
openjdk version "1.8.0_382"
OpenJDK Runtime Environment (build 1.8.0_382-cvm-b00)
OpenJDK 64-Bit Server VM (CompoundVM 8.0.0) (build 17.0.8+0, mixed mode)
Notice the VM version, JVM 17 has been enabled in a JDK 8!
See CONTRIBUTING.md