High ms MinecraftEdu Local Server

[Gibwan]

On one of our old servers, we run MinecraftEdu for the students. There is only maximum 30 students playing at one time and the ms seems to correlate with how many people join the server.

We consistently get the error "Can't keep up! Did the system time change, or is the server overloaded? Running 22563ms behind, skipping 451 tick(s)" but RAM will be at 3% usage, CPU at 30-40% and the server goes straight into the core switch (10Gb) which is connected by fibre (10Gb) to the IT suite switch and then clients are connected to this switch (1Gb).

 

We have around 10 mods installed.

 

For the life of us we can't figure out why we get these high latencies. Our server specs below:

 

Intel Xeon CPU E5640 @ 2.67 Ghz (2 Processors)

32Gb RAM

4X 500Gb HDD in RAID 10

 

It's incredibly frustrating for the students, as sometimes it can take over a minute to mine one block.

If anyone can point us in the right direction. That would be fantastic!

[DGardiner]

Isnt the server largely single threaded, if you check the cpu its probably maxed out on a core - you can try setting the affinity of the process may be to shift it off the first couple of cores to gain a little performance.

 

 

other than that its probably just a case of fine tuning the server settings , if you can get mods running using something to make a hard server wall and then pre generating the world to that border would stop that having to be done on the fly and reduce that overhead but i havent done anything with minecraft in a long while! so no idea where to start

[bald_pig]

On top of what JGardiner said, the JVM will only use as much RAM as you tell it to use in the server config, so make sure that it hasn't hit that limit.

[Gibwan]

@DGardiner This is very useful and something i didn't realise. I'll monitor this when they use the server today. I'm assuming it's not possibly then to force the server to use all cores?

 

@bald_pig Unfortunately this is something we have already made sure of.

[Gibwan]

@bald_pig Looking through our config file. These are our launch parameters:

 

launch-parameters=%JAVAEXEC% %PERFORMANCEPARAMS% -Xmx%RAM%M -Xms%RAM%M -jar %SERVERTYPE%_server.jar

 

is there anything that could be changed to improve performance?

[Gibwan]

UPDATE: Monitored over the hour session and none of the cores maxed out. No overheating. Still ms spikes...

[bald_pig]

Are you able to post the entire config?

[DGardiner]

UPDATE: Monitored over the hour session and none of the cores maxed out. No overheating. Still ms spikes...

 

odd, Whats the disk read/write like - it may be choaking pulling chunk data to memory/clients