jmh VS picocli

JMH for benchmarks

I would recommend using JMH instead.

Reflection is probably very roughly between 10 and 1000 times slower. Why don't you measure it yourself using JMH?

Aleksey Shipilev is another such leader, whom is especially knowledgeable about the internals of the JVM. His writings are invaluable. He is (was) the lead of the Java microbenchmark framework (JMH} which is how one would write small performance experiments in Java, and learn what really makes a difference or now.

In the last episode we implemented a parallelMap operation using streams, raw threads, a threadpool with futures, and coroutines. At first glance the raw threads was quickest, followed by futures, coroutines and then streams. In this, part 56 of an exploration of where a Test Driven Development implementation of the Gilded Rose stock control system might take us in Kotlin, we investigate the performance of the different functions further, in particular digging down into why coroutines seem to be slow and finding a way to speed them up. We also find a way to use a particular ForkJoinPool to run the streams code, making it as fast as the others (bar the raw threads). Frankly we only use very rough benchmarks here, with no statistical testing except 'it looks like'. That's OK for gross differences, but is highly suspect when deciding which of two similarly performant approaches is faster. For that check out JMH and you could watch my video from KotlinConf 2017

A few months ago, we started to use JMH in our project to test and find performance issues. The tool provides multiple modes and profilers, and we found this useful for our purposes.

Picocli allows using a compiler annotation processor to generate classes at compile time instead [0].

[0]: https://github.com/remkop/picocli/blob/main/picocli-codegen/...

Picocli is a pretty good one for writing CLI apps

"and there are simply no good command line input parsing libraries for Java."

Looks like author missed the most obvious and popular OSS one: https://picocli.info/

The command line example gave me the "ick". It is usually preferrable to parse the command line arguments into one instance of a custom "command class", rather than into a list of things. Like jcommander, picocli or jbock do.

Complex argument parsing needs to be auto-generated by libraries like picocli. Even if you need something custom, it'd be quicker to write an Annotation processor from scratch than editing that file.

https://github.com/remkop/picocli

"Picocli-based applications can be ahead-of-time compiled to a GraalVM native image, with extremely fast startup time and lower memory requirements, which can be distributed as a single executable file."

https://picocli.info/quick-guide.html

Using picocli to handle your command line options gives you the best chance to automatically generate an ArgumentCompleter script in the future, but won't help you today (other than possibly making your command line handling more standardized & easier).

Picocli

Then we released a JBang! and picocli based cli that would be, on any OS running a jvm runtime :

picocli : "a mighty tiny command line interface"