Jmh

External

• http://openjdk.java.net/projects/code-tools/jmh/

Overview

Introduced by Java 8 & 9 in Action.

Example

https://github.com/NovaOrdis/playground/tree/master/java/jmh

The Maven shade plugin configuration available here: Maven Shade Plugin.

Annotations

@Benchmark

@Benchmark annotates the benchmark method.

JMH will produce the generated benchmark code for this method during compilation, register this method as the benchmark in the benchmark list, read out the default values from the annotations, and generally prepare the environment for the benchmark to run.

Benchmarks may use annotations to control different things in their operations.

* See {@link org.openjdk.jmh.annotations} package for available annotations, read their
* Javadocs, and/or look through
* <a href="http://hg.openjdk.java.net/code-tools/jmh/file/tip/jmh-samples/src/main/java/org/openjdk/jmh/samples/">
* JMH samples</a> for their canonical uses. As the rule of thumb, most annotations
* may be placed either at the {@link Benchmark} method, or at the enclosing class,

* to be inherited by all {@link Benchmark} methods in the class.

*

*

{@link Benchmark} demarcates the benchmark payload, and JMH treats it specifically * as the wrapper which contains the benchmark code. In order to run the benchmark reliably, * JMH enforces a few stringent properties for these wrapper methods, including, but not * limited to:

*

*
• Method should be public
*
• Arguments may only include either {@link State} classes, which JMH will inject * while calling the method (see {@link State} for more details), or JMH infrastructure * classes, like {@link org.openjdk.jmh.infra.Control}, or {@link org.openjdk.jmh.infra.Blackhole}
*
• Method can only be synchronized if a relevant {@link State} is placed * on the enclosing class.
*

*

*

If you want to benchmark methods that break these properties, you have to write them * out as distinct methods and call them from {@link Benchmark} method.

*

*

Benchmark method may declare Exceptions and Throwables to throw. Any exception actually * raised and thrown will be treated as benchmark failure.