Based on Java Microbenchmark Harness (JMH), this feature adds a basic suite of microbenchmarks to the JDK source code, with the following proposed directory structure:

jdk/jdk
    .../make/test
    .../test
       .../micro/org/openjdk/bench
           .../java
                .../vm

Since the microbenchmark suite will be located with the JDK source code, it will make it simpler for developers to locate and run existing microbenchmarks, and create new ones. As existing features are updated or removed from a JDK version, it will be simple to update a microbenchmark. Also, when developers run a microbenchmark they can use JMH's powerful filtering to run selected benchmarks.

Although the microbenchmark suite and its building will be integrated with JDK and its build system, it will have a separate target. Developers will need to specify additional parameters to execute it to keep the build time for normal JDK low.

As the name suggests, with benchmarking you can compare builds or releases. Hence, the microbenchmarks support JDK (N) for the new JDK and JDK (N-1) for the previous release. The benchmarks depend on JMH in the same way that unit tests depend on TestNG or jtreg. JMH is used during the build process and is packaged as part of the resulting JAR file.