One online player lockes out server CPU for one core (forge)

Hey all, first post here. I have been looking around for like 2 days now and cant really find what im looking for.

I have a clean install of mineos (mineos-node_jessie-x64 downloaded from the site yesterday) and installed it into virtualbox on a freenas (freebsd) system. The mineos is running nicely and works fine. I created a Forge mod server and added a few mods. it loads up ok. after its loaded, CPU usage drops to a respectable idle if like 0.05 something. When just 1 client connects there are a few processes that start doing there thing but one process is always around 80-90%. that process does switch cores sometimes but is always around that 80-90% and sometimes more to 100% and then the server starts lagspikes and i get the message “server cant keep up…”. Also when other players start to join (total of 2 a 3 players online) that same process just locks at 100% and the lags get worse…

is there a way to force it to spread out over multiple cores? at the moment i have no additional arguments for java or the jar.

Picture of idle server:
Picture of 1 user online:

Thanks for the help :slight_smile:

Host system specs(hardware):
Board and CPU: asrock C2750D4I 8cores @2.4GHz
RAM: 32GB ddr3 1333
Disk: 16.5 TB

VM system specs:
same board and cpu (8 cores) patched
500GB disk space

Forge version: 1.9.4 build 1968
Pam’s HarvestCraft 1.9.4b.jar
StorageDrawers-1.9-3.1.7 (1).jar

This is a java-problem, and there is given a possible solution here:

However, I have not tried this in the MineOS envorinment. The solution given above is dependandt on using JDK in stead for JRE.

There is also a longer diskussion on this on the Spigot forum ( and the old Bukkit forums (

I think the answer to your question is that it is java and operating system dependant. So googling your java installation and how to tweak it to use several cores.

1 Like

Thanks for the information… at least i know in what way i need to look :slight_smile: ill give the links a try

Well i had a try, i added the arguments but it seems to do nothing. Can someone help me to tell mineos to use jdk instead?

I use at the console as ‘root’ with good effect:

sh -c ‘echo “deb precise main” >> /etc/apt/sources.list’

sh -c ‘echo “deb-src precice main” >> /etc/apt/sources.list’

apt-key adv --keyserver --recv-keys EEA14886

apt-get update

apt-get install oracle-java8-installer

Please take note of every stroke, space, cap ", ’ , >> and letter.

Good Luck!


By the way, it has been mentioned that minecraft was by default due to java created as a single core/thread program and is best used in a single core.

I do set my VM’s to use 2 of the servers 8 available cores with ok results and I try to avoid allocating ‘too much ram’ to such a ram glutton as java, lol.

You will not get rid of the “server cant keep up…” warnings but they should slow down some.


im installing now… i probably do need more cores and the ram… its going to be a big server, 70 to 100 people

Im going to test soon if it helps, i do need people online to test though

I installed it and now have like 6 people online and its still the same. That one core is being used most but apart from that process, other processes do use other cores… i dont know if its a mod that is using so much or that its the main process… thy are all called the same…

But it didnt matter much if one player was online or more… maybe i should just leave it and deal with lag when people are exploring…because thats when the lag happens most

You’re Gonna Need a Bigger Boat - Jaws

The server will have to generate terrain and spawn mobs (animals, villagers etc.) for each player as they move. All adding to load, plus if you use mods/ texture packs that also adds to that load for each player.

Good Luck!


I fiddled with it for a bit and got it working now, installing the jdk java and pointing to the right java version did the trick

do test out witch java jdk versions work, i had to install - remove some a few times before it did work.