Well-Grounded Java Developer: JMH

[German Gonzalez-Morris]

Hello,

Is there a chapter that discusses JMH?

It may be useful in this context, but I didn't find anything in the TOC.

Regards,

Germán

[Ben Evans]

The performance chapter doesn't cover JMH.

There is some material about it in my book "Optimizing Java" (O'Reilly) - but I do advise caution.

In practice, very few Java developers really need to use JMH. It is *not* a general-purpose benchmarking tool but instead is useful in a couple of special cases.

When doing general application performance analysis, you need to start with a "top-down" approach, rather than a "bottom-up" one.

[Martijn Verburg]

Adding to this.  It's very much a tool that is used by VM Engineers (folks who work on the JVM/HotSpot itself) or who write really small functions/libraries that need optimizing (low latency trading systems comes to mind).  Often high level application developers will be misled by this tool when a micro-optimization may not realise into a gain in their app.

[Stephan van Hulst]

Even though for general application development, the use of micro-benchmarking frameworks is limited when compared to profiling tools, I will say that JMH is very useful for verifying any assumption you might make about basic data structures that are provided by the standard library.

For example, I find it very satisfying to see for myself how an ArrayDeque compares to a LinkedList performance-wise, when used as a simple stack.