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Seriously uncool Java?

A couple of podcasts I have listened to recently have flamed Java. It is a good "kusitolppa", a seriously uncool technology.  I'm pleased about not having to write Java anymore. Yet, I'll risk career suicide and take a stance to defend it against some of the low blows. After all, it was my bread and butter for quite many years.

I get it; writing Java is not in fashion. It is likely a wrong choice for a modern startup. The language is full of mysterious cargo-cultish traditions, is verbose, has annotations on top of annotations and you have to use an editor which eats half of your memory (the other half is used by the Java process you are working on). Traditional Java and JDKs are ill-fitted for short-running processes like lambdas; it needs time to warm to get up to speed and needs more than one core to work efficiently. It has horrible dependency management tools by today's standards. Running a JVM process requires all kinds of weird flags, its defaults are unlikely suitable for any given project.

An often pointed out defect in the old-school Java frameworks is their excessive use of threads. Granted, the traditional, solid but inefficient, thread-per-request model has been pervasive for too long. It's funny why, since the standard library has had the fork-join work-stealing type thread pool in for a decade. You are supposed to use that, preferably through a library or a framework, and never create threads yourself.

Speaking of frameworks, It's not trivial to figure out what is a good JVM framework. The de facto choice is Spring Boot or something expensive from RedHat. I would steer clear of those enterprisey frameworks and pick something like Micronaut or Quarkus. They have a fast startup speed,  don't need massive thread pools (non-blocking IO), and use code generation rather than runtime reflection. I won't even try to do or link any study on their performance compared to other frameworks from other languages since it is notoriously tricky, but I'm sure they are in the triple-A class.

GraalVM's ahead-of-time compilation can speed up startup and reduce the docker image sizes. The new CG's, ZGC and Shenandoah, have finally enabled massive heaps with low latency stop-the-world pauses. Since JDK 8, tiered JIT allows complex, heterogenous codebases to run fast after a warmup period. If a warmup time is not an option, Quarkus with Graal AOT compiled native image should do the trick.

I could go on about how slow and somehow uncomfortable Jest feels compared to plain old JUnit, and what a mess I see when I want to check the TypeScript definitions from the editor compared to the dull but very readable JavaDoc. I love writing TypeScript in VSCode, but I do spend a lot of time resolving all kinds of weird double import errors. IDEA was laggy and slow to start, but it did a lot of coding for me.

My conclusion here is that I would not personally start a new Java project and certainly would not build a startup with Java, but at the same time, I should not discard the JVM ecosystem so blatantly. If I were to choose the JVM, It's a no-brainer to use something like Kotlin or Clojure to get the best of both worlds, a solid runtime, and an expressive programming language.

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