What are the best Java arguments to use?

[Interplay]

Well...

 

The title says everything. Everybody knows we need to use this one:

-Xmx4G

But these ones comes by defaut in the Minecraft Launcher:

-XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=16M

Are they good? I don't even know what they do... =P

If not, what elese should I add that will help in my gameplay...

[ichttt]

Cpw made a really good reddit post about this were he explains what he uses as JVM arguments.

I use them as well for large modpacks (and with lower memory like 2G for lightweight modpacks)

 

[Hankt]

Are these arguments valid for the minecraft server.jar as well?  I am trying to optimize a home based server setup for my daughter and her friends. It is running on an Intel core duo core 2.2ghz processor with 8gb ram.

 

There are never more than about 8 kids playing, but the stutter and rebreaking the same block lag are annoying.

The machine used as a server is connected to the internet using fiber and network traffic is small.

Current command line:
-Xmx4G -Xms4G -Xmn96M -XX:UseSSE=3 -XX:+UseG1GC -Dsun.rmi.dgc.server.gcInterval=2147483646 -XX:+UnlockExperimentalVMOptions -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M -XX:+AggressiveOpts -XX:SurvivorRatio=16 -Xnoclassgc -server -jar server.jar nogui

[Hankt]

1 minute ago, diesieben07 said:

Most likely you just have not enough processing power. Have you checked CPU usage? 

Throwing more options at Java will usually just make things worse unless you know what you are doing.

It sits at 14-18% at idle and up to 50% during game play. It could be CPU, but there is nothing else running on this machine.

 

[Hankt]

15 hours ago, diesieben07 said:

If it sits at 50% that means the one core that the Minecraft server will use is fully utilized.

Re-read that. During gameplay, it can get to 50%. I am running Java 64 and minecraft server has been multi-core capable since 1.14.

Before optimizing java settings, it would get as high as 80 odd %.

I ran this setup on Ubuntu on an older Acer Aspire laptop with the 1.67ghz Intel Duo with only 4gb of ram and it screamed. I never saw the "server is behind xx ticks" message. I didn't have all the config flags running that I do in Windows and memory settings were 512 and 2048

Either there is something missing or the overhead of Win 10 is a bottleneck to achieving better performance.

Next up, my original question, are these parameters valid for server.jar?

[dragontuar]

i just updated to java 17 been searching for some stuff like why minecraft uses the javaw exe over java exe or javac exe then a quick look for any useful jvm args and here is what i have (my minecraft runs with it) 

 

 

-XX:+UseG1GC -XX:ParallelGCThreads=12 -XX:+DisableExplicitGC -Dsun.rmi.dgc.server.gcInterval=2147483646 -XX:+UnlockExperimentalVMOptions -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M -XX:SurvivorRatio=16 -Xnoclassgc