For some reason when I went to update some files on my server I got this error:

 

java.lang.OutOfMemoryError: Java heap space

at ge.<init>(World.java:188)

at gp.<init>(WorldServer.java:26)

at hy.<init>(SourceFile:10)

at net.minecraft.server.MinecraftServer.initDimension(MinecraftServer.java:690)

at net.minecraft.server.MinecraftServer.a(MinecraftServer.java:743)

at mod_EE.onTickInGame(mod_EE.java:120)

at BaseMod.doTickInGame(BaseMod.java:41)

at cpw.mods.fml.common.modloader.BaseModTicker.tickBaseMod(BaseModTicker.java:65)

at cpw.mods.fml.common.modloader.BaseModTicker.tickEnd(BaseModTicker.java:54)

at cpw.mods.fml.common.FMLCommonHandler.tickEnd(FMLCommonHandler.java:127)

at cpw.mods.fml.server.FMLServerHandler.onPostServerTick(FMLServerHandler.java:157)

at net.minecraft.server.MinecraftServer.w(MinecraftServer.java:604)

at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:450)

at dn.run(SourceFile:492)

 

However I have never had this error, I think this may be a possible error with mystcraft but I am unsure, I think this because it is the only mod I have added other than updating a few mods.  Also my terminal (cmd/ default server jar running) will not accept any commands that I type into it.  Does anybody have any advice? (Other than the obvious "DONT USE MYSTCRAFT", as I would very much enjoy adding it to my server.

One solution would be to use 64 bit java. 32 bit Programs are limited up to 2GB of memory. Other solution is to allocate more memory when run MC, but on 32bit application is not possible to go past 2GB limit.

MystCraft uses a crap-ton of memory to load all the worlds, you need to have a pretty beefy server as well as a well set up Minecraft server with enough memory allocated to it.