Possible performance problem with UnmodifiableConfig

I was analysing my Minecraft setup with JFR to find mods that were misbehaving. One of the hottest methods from outside Vanilla came from LambDynamicLights. (In the JFR recording, I just stood still and looked around my base.)

The hot method is Arrays.copyOf(Object[], int) which is responsible for > 1% of all CPU cycles. The stack trace leading to this is:

java.util.Arrays.copyOf()
[JDK internal stuff]
java.util.ArrayList.add()
dev.lambdaurora.lambdynlights.shadow.nightconfig.core.utils.StringUtils.split()
dev.lambdaurora.lambdynlights.shadow.nightconfig.core.UnmodifiableConfig.getOrElse()

which is called from dev.lambdaurora.lambdynlights.DynamicLightsConfig.hasEntitiesLightSource() and dev.lambdaurora.lambdynlights.DynamicLightsConfig.hasBlockEntitiesLightSource(), respectively.

I have not dived into the the source code yet, but by the name of the class, it sounds like getting an “Unmodifiable Config” should not really have to do a string split (which ends up doing array copies) each time it is called. I imagine there is some easy room for improvement here.

Let me know if you want me to submit a PR with a fix. (I suspect a developer familiar with the code can make it quicker than I, but I’m willing to help if there is not enough resources on the project.)

[LambdAurora]

Let me know if you want me to submit a PR with a fix. (I suspect a developer familiar with the code can make it quicker than I, but I’m willing to help if there is not enough resources on the project.)

Very sorry but while reading I totally missed this part, feel free to PR, I’m not currently much available so any help is appreciated.

[magicus]

Fixed by commit 2678e56a2fc63531f2d9d9f59dfafdab7217f88e.