afterburner/blackbird usage?

[sixcorners]

How are you supposed to use the afterburner and blackbird modules? Is it ok to just throw both into the project as runtime dependencies and then make sure that findAndRegisterModules() is called at runtime? Will the correct thing happen in jdk 8, 11, and 17? And graal too I guess. I don't know anything about graal. If I want to run on 8 and 17 do I need to make one use afterburner and another use blackbird or just decide to fully go with blackbird?

[cowtowncoder]

Wrt. registering the module, yes, you can traditionally either:

1. Explicitly register module on ObjectMapper (via builder.addModule() or mapper.registerModule(), OR
2. Use auto-discovery with ObjectMapper.findAndRegisterModules()

Personally I am a big fan of explicit set up (1) and prefer that to avoid accidentally registering other modules that may be on my classpath, but YMMV.

However! With frameworks like Quarkus and Micronaut that do lots of heavy-lifting during build phase, auto-discovery may not work without some help: I would verify its functioning.
And even more so with Native Images (Graal). In those cases explicit registration may be less work than configuring things to include necessary SPI metadata: information needed for auto-registration comes from META-INF/services/com.fasterxml.jackson.databind.Module entry in JAR.

As to JDK versions: Afterburner works well for older JDKs, but Blackbird should work better with later (and Afterburner probably won't work well at all with 17+). So for future usage, Blackbird should take over.

[sixcorners]

So with current usage is it fine to throw both into the project and let them fight it out? Will afterburner work when my project is running under java 8 and blackbird in java 17?

[cowtowncoder]

No, modules are fully isolated from each other and have no knowledge of each other.

In this case either neither or both would be activated. So ideally you use only one. But coordination is outside control of modules.

[magicprinc]

How safe to use them?

And what is the benefit in terms of speed?

My non-scientific tests (no JMH, with warm-up and black hole) show floating speedup factor between 0 and 10%.

[cowtowncoder]

Really depends: they help mostly when reading/writing POJOs: no speed up for JsonNode (for example).
Speed up for optimal cases that I have seen in benchmarks is between 20 and 40%.

As to safety, there is always possibility of behavior being slightly different from default processing, because Afterburner/Blackbird override (re-implement) serialization/deserialization of properties of some simple scalar types (int, long, boolean, String).
Not the part that JsonGenerator/JsonParser do but JsonSerializer/JsonDeserializer handling.