Server Lag

[Cosmology27]

So I'm running a monster server, but I've added a bunch more mods to it. I'm running 4-6 gigs of ram, and there's very few on the server, usually only one or two at a time, and most the day there's no one.
Here's the problem. I can shut down my computer for the whole night, turn on the server, with NOTHING else running on my computer, and it'll still say the "Can't keep up!" message about once or twice every minute. I mean, there's no one on the server, my computer just booted up, there's nothing else running... why is it not able to keep up? When I am on the server, I get a little bit of lag (block and mob lag), basically all the time, but only a minor problem. I have 6 gig allotted to this thing, which is way more than enough. Here's the java stuff I'm running it with.

#!/bin/bash
cd "$(dirname "$0")"
exec java -Xms4G -Xmx6G -XXermSize=256m -jar FTBServer-1.6.4-965.jar nogui


I'm sure this is because I have so many mods running, but even then you would think it would be fine. Does anyone know anything that could help me make this run smoother?
Thanks!

 

[TheAwesomater]

So I'm running a monster server, but I've added a bunch more mods to it. I'm running 4-6 gigs of ram, and there's very few on the server, usually only one or two at a time, and most the day there's no one.
Here's the problem. I can shut down my computer for the whole night, turn on the server, with NOTHING else running on my computer, and it'll still say the "Can't keep up!" message about once or twice every minute. I mean, there's no one on the server, my computer just booted up, there's nothing else running... why is it not able to keep up? When I am on the server, I get a little bit of lag (block and mob lag), basically all the time, but only a minor problem. I have 6 gig allotted to this thing, which is way more than enough. Here's the java stuff I'm running it with.

#!/bin/bash
cd "$(dirname "$0")"
exec java -Xms4G -Xmx6G -XXermSize=256m -jar FTBServer-1.6.4-965.jar nogui


I'm sure this is because I have so many mods running, but even then you would think it would be fine. Does anyone know anything that could help me make this run smoother?
Thanks!

You. Old remove mods from the server and client. Is your machine good enough on the server ie have you run other servers before, what pack, players etc.

Try opis to see bad tick rate.

 

[Harvest88]

Your are running out of memory some how according to that "can't keep up" message. Even though 6GB is plenty makes sure your computer actually have that (check your task manager to see much memory and CPU is being used up and at the ready). It may be the simple fact that because your using desktop grade memory sticks that cannot keep up with memory demands. Hosts running on modern CPUs are running on DDR3 RAM running at 1333Mhz (rarely clocked to 1600Mhz). So what I am saying in short even if you actually have memory to spare it may not be "fast" enough to keep up.

 

[RealSketch]

OPIS should help, it's especially made for servers and decreasing lag.

 

[Harvest88]

OPIS should help, it's especially made for servers and decreasing lag.

Not exactly, it does help but it doesn't directly lower lag. It will however help you find out what is taking the most load on your server and then you can take proper actions with those hogs.

 

[TheAwesomater]

Not exactly, it does help but it doesn't directly lower lag. It will however help you find out what is taking the most load on your server and then you can take proper actions with those hogs.

Which helps, since most lag is caused by bad builds etc that people make mistakes on.

 

[Harvest88]

Which helps, since most lag is caused by bad builds etc that people make mistakes on.

Exactly, I was just being clear about how it works and that it doesn't do anything about the lag directly (unlike TT used to in 1.5.2).

 

[Demosthenex]

Check the Opis report, that's an excellent starting point. Another is to see how many chunks are loaded, especially if there are many chunk loaders.

 

[Cosmology27]

So I've installed opis on my monster server, and I'm trying to open the interface by /opis, and it does nothing. Then I try it in the server console thing, and it says...

2014-06-14 17:55:39 [INFO] [Minecraft-Server] You are not a normal client and can't open the Swing interface.

Any ideas?

Also, my computer has 10 gig of ram, so it's definitely able to use 6 gig.
Also, I think I found the problem, in a part of the map Lycanites Mobs has literally hundreds of mobs spawning, because apparently there is no max mob amount for Lycanites... which is weird. If I get opis working properly, I can use the /killall thing, but right now the interface won't open.