Add ZGC Option for MeowIce Flags

[jamstruth]

Enhancement Type

Improve an existing feature

Describe the enhancement

MeowIce provides 2 versions of the flags - one using the standard G1GC and the other using ZGC.

ZGC is a latency focused garbage collector which may have some benefits for higher end CPUs in reducing stutters due to garbage collection.

[itzg]

As a Java developer for almost 30 years I'm so confused why they even offer the G1GC flags. ZGC is default and ideal for any JVM on Java 25 or newer.

Are you thinking the selection should be based on heap allocation size (ie MEMORY env var)? Or just expose another env var to choose between them?

[jamstruth]

I think at least providing a force meowice ZGC flag would be a good idea to allow people to test it out.

Tbh the reviews that are around of ZGC for Minecraft servers aren't that great. I only raised this because Distant Horizons has a little warning recommending it but it seems the consensus is that it's more CPU overhead for small heaps. Apparently it causes memory spikes during chunk loading.

[itzg]

Thanks! That is very helpful information and makes me feel better having ZGC opt-in and/or have it switch to that when MEMORY/MAX_MEMORY is over 32GB

[itzg]

Note to self or contributors:

I really want to refactor the Aikers and Meowice handling from here

docker-minecraft-server/scripts/start-finalExec

Line 226 in a69017b

if isTrue "${USE_AIKAR_FLAGS}" || isTrue "${USE_MEOWICE_FLAGS}"; then

Into its own script file that is called from that location.

There's also a bit too much complexity now in the decision making between the the two flag types, max memory requested, graalvm, etc. Maybe that could be be simplified and separated when it is in its own file.