[SEVERE] java.lang.OutOfMemoryError: GC overhead limit exceeded

Does anyone know why i am getting those messages?
Here's the pastebin:
http://pastebin.com/22FDwu4W

I guess is something about de Garbache Collector of Java, how can i fix that? Or why is it happenig?

Im using this to run the server: java -d64 -Xms2048M -Xmx2048M -jar craftbukkit.jar

Java: Sun Microsystems Inc. 1.6.0_22
OS: Linux 2.6.34.6-xxxx-grs-ipv6-64 (amd64)
Bukkit: git-Bukkit-0.0.0-945-g73697a4-b1000jnks (MC: 1.7.3)

-------
Plugins
-------

HeroSpawn : 0.2
SpyerAdminCommands : 1.4 stable
MobBounty : 4.05
Permissions : 3.1.6
GroupSpawn : 1.4
AutoMessage : 1.5
HeroChat : 4.10.3
SpyerAdmin : 1.4 stable
xAuth : 2.0b3
SimpleRestart : 1.1.0
WorldEdit : 4.6
Towny : 0.73.1
PermissionsPlus : 3.2
SignLift : 0.7
OpenInv : 1.3.1
MinecraftViewer : 1.0c
iConomyDeath : 0.7
iConomy : 5.01
MCDocs : 10
PermissionsSql : 1.3
Votifier : 1.4
AppleTree : 0.5.1
dynmap : 0.19.2
Landmarks : 0.2
WorldGuard : 5.2.2
Minecart Permanence: 1.0.0
Minequery : 1.5
Questioner : 0.4
WurkIt : 1.1.1
HeroicDeath : 1.8.1.156
p2Aliases : 1.3

 

Maybe not THAT powerful machine? Do you have 2 gig of ram free?

 

I can use 4 or 8GB, but i don't want to waste RAM, i want to know why is that error. For me, it seems (i have check with /memory command of Towny and SimpleRestart) that when you start server there is like 1.4GB free ram. 1 minute later like 600Mb free. 2 minutes later like 100Mb. And then just keeps about 100Mb free ram for days.
Would it be any difference using 3 or 4G?

Please, some help here? :S

EDIT by Moderator: merged posts, please use the edit button instead of double posting.