A Quick look at Quarkus

Microservice Framework

Quarkus depends a lot on SmallRye "a set of implementations of the MicroProfile specifications. We said that Quarkus is also a MicroProfile implementation, so this begs for a bit of explanation. Each SmallRye project implements one of the MicroProfile specifications" [1].

The MicroProfile specification is a set of standards for building microservice containers - for instance, handling Kubernetes health checks etc.

Native code

GraalVM has two main features: 

• it allows polyglot development
• it allows Ahead-of-Time (AOT) compilation.

This latter features is what Quarkus is interested in, although "Mandrel is a downstream (forked) distribution of the Oracle GraalVM CE with the main goal of providing a way to build a native executable specifically designed to support Quarkus... Mandrel focuses mainly on the native-image build tool. It doesn’t provide a full GraalVM toolset." [1]

Generate the binary with:

mvn package -Pnative

This defers to GRAALVM_HOME/bin/native-image and gcc. 

If we delegate to Graal, why use Quarkus at all? Well, Graal struggles with reflection. Quarkus provides shims that mean popular frameworks don't use reflection and can therefore be turned to native code.

Note that just because it produces an executable binary, the artifact still needs a garbage collector. In the output, you'll see:

Garbage collector: Serial GC (max heap size: 80% of RAM)

You don't need to use Quarkus to build native executables, though. For instance, if you tried to convert the Java port of Llama.cpp, you can build it with just make native - although note that I had to use version 24 of GraalVM as earlier versions didn't like the use of AVX (vector extensions).

Thread management

Much like Scala's Cats and ZIO, Quarkus facilitates execution engines. For instance it has a notion of blocking threads. "The @Blocking annotation on both methods tells Quarkus that the method executes a blocking operation (persist or delete) on a database, so it needs to execute on worker thread, which allows blocking." [1]

PolarisPrincipalAuthenticatorFilter

[1] Quarkus in Action (Manning)