Java Microbenchmarking Harness demo

The repository contains a simple example benchmark configured with annotations (BasicBenchmark) plus three examples of pitfalls to avoid when writing your own benchmarks:

• LoopOptimization (in Java, so that the compiler actually optimizes the loop) - notice how the throughput is independent of the number of iterations
• DeadCode - notice how the method with unused result outperforms those where the result is actually used
• ConstantFolding - notice how using constants inside the tested methods can produce misleading results (the computation may actually never happen)

Running

sbt "jmh:run <ClassName>"

e.g.

sbt "jmh:run LoopOptimization"

Disclaimer

Never forget about the following when looking at the benchmark results:

[info] REMEMBER: The numbers below are just data. To gain reusable insights, you need to follow up on
[info] why the numbers are the way they are. Use profilers (see -prof, -lprof), design factorial
[info] experiments, perform baseline and negative tests that provide experimental control, make sure
[info] the benchmarking environment is safe on JVM/OS/HW level, ask for reviews from the domain experts.
[info] Do not assume the numbers tell you what you want them to tell.