I have a RAM problem (6 gig's Is Not Enough?!) for 20 peoples ?!

Every time same error .... im mad ...

max 20 players play in the server, same error after 2-3 hours ....

i want to try Sceen but cannot run it ...
Can someone tell me a Script to run the server ?
how to run this Screen .... have sesion error ... how to create this sesion ?
Is there a video in youtube or something else ?

Code:

2011-10-07 20:30:41 [INFO] Connection reset
2011-10-07 20:30:59 [INFO] Read timed out
2011-10-07 20:30:59 [SEVERE] java.net.SocketException: Socket closed
2011-10-07 20:30:59 [SEVERE]     at java.net.SocketOutputStream.socketWrite(SocketOutputStream.java:116)
2011-10-07 20:30:59 [SEVERE]     at java.net.SocketOutputStream.write(SocketOutputStream.java:153)
2011-10-07 20:30:59 [SEVERE]     at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)
2011-10-07 20:30:59 [SEVERE]     at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:140)
2011-10-07 20:30:59 [SEVERE]     at java.io.DataOutputStream.flush(DataOutputStream.java:123)
2011-10-07 20:30:59 [SEVERE]     at net.minecraft.server.NetworkWriterThread.run(SourceFile:104)
2011-10-07 20:30:59 [INFO] Connection reset
2011-10-07 20:31:00 [INFO] Connection reset
2011-10-07 20:31:00 [INFO] Connection reset
2011-10-07 20:31:00 [INFO] gosheto lost connection: disconnect.endOfStream
2011-10-07 20:32:55 [INFO] Connection reset
2011-10-07 20:38:03 [SEVERE] java.lang.OutOfMemoryError: Java heap space
2011-10-07 20:38:03 [SEVERE]     at net.minecraft.server.World.getMultiChunkData(World.java:2355)
2011-10-07 20:38:03 [SEVERE]     at net.minecraft.server.Packet51MapChunk.<init>(Packet51MapChunk.java:28)
2011-10-07 20:38:03 [SEVERE]     at org.getspout.spout.MapChunkThread.sendPacketMapChunk(MapChunkThread.java:214)
2011-10-07 20:38:03 [SEVERE]     at org.getspout.spout.MapChunkThread.sendPacketMapChunk(MapChunkThread.java:205)
2011-10-07 20:38:22 [SEVERE]     at org.getspout.spout.SpoutNetServerHandler.manageChunkQueue(SpoutNetServerHandler.java:688)
2011-10-07 20:38:22 [SEVERE]     at org.getspout.spout.SpoutNetServerHandler.a(SpoutNetServerHandler.java:603)
2011-10-07 20:38:41 [SEVERE]     at net.minecraft.server.Packet10Flying.a(SourceFile:126)
2011-10-07 20:38:41 [SEVERE]     at net.minecraft.server.NetworkManager.b(NetworkManager.java:226)
2011-10-07 20:38:41 [SEVERE]     at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:92)
2011-10-07 20:39:42 [SEVERE]     at org.getspout.spout.SpoutNetServerHandler.a(SpoutNetServerHandler.java:500)
2011-10-07 20:39:42 [SEVERE]     at net.minecraft.server.NetworkListenThread.a(SourceFile:108)
2011-10-07 20:40:17 [SEVERE]     at net.minecraft.server.MinecraftServer.h(MinecraftServer.java:471)
2011-10-07 20:40:46 [SEVERE]     at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:374)
2011-10-07 20:42:43 [SEVERE]     at net.minecraft.server.ThreadServerApplication.run(SourceFile:417)
2011-10-07 20:45:16 [SEVERE] Exception in thread "Listen thread"
2011-10-07 20:46:24 [INFO] Stopping server

Starting script:
java -Xincgc -Xmx4096M -Xms512M -jar craftbukkit.jar nogui

i try this too, same thing ... :
#java -native -server -Xincgc -Xmx4096M -Xms512M -Xmn512M -XX:NewRatio=3 -Xrs -XX:+UseThreadPriorities -XX:CMSFullGCsBeforeCompaction=1 -XX:SoftRefLRUPolicyMSPerMB=1024 -XX:+CMSParallelRemarkEnabled -XX:+UseParNewGC -XX:+UseAdaptiveSizePolicy -XX:+DisableExplicitGC -Xnoclassgc -oss4M -ss4M -XX:+UseFastAccessorMethods -XX:+UseCMSInitiatingOccupancyOnly -XX:CMSInitiatingOccupancyFraction=75 -XX:+UseConcMarkSweepGC -XX:UseSSE=3 -XX:+UseCMSCompactAtFullCollection -XXarallelGCThreads=2 -Xcheck:jni -XX:+AggressiveOpts -cp "craftbukkit.jar" -jar "craftbukkit.jar" nogui

Info:
OS: Ubuntu 11.05 64bit
6GB ram
Athlon64 4800+ (2x2.5Ghz)

Crafbukkit 1.8.1
python/lampp/mysql ...

plugins:
AutoAnnouncer
BananaLogArchiver
bAntiCaps
ButtonWarp
ChestShop
Essentials
EssentialsGeoIP
FalseBook
FoundDiamonds
GroupManager
HawkEye
iConomy
InventorySave
LagMeter
Lockette
MinecraftViewer
MobBounty
MyWarp
NoCheat
OKSpamSecurity
Residence
ScizzrHome
Spout
Stargate
Vanilla
VanishNoPacket
WorldEdit
WorldGuard
xAuth
CFBanner

How to check what is my java 32 ot 64 bit ?

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

 

hrm, on linux it would be something like, java --help or java --version I would think.

 

cpu also matters too

 

As for that, your startup script looks like it's to blame, what's wrong with keeping it simple?

It could also be that you have an extremely leaky plugin set.

 

How to find who plugin is leaky ?

 

What would you suggest a simple startup script with proper garbage collecting would look like? Do tell, I am always looking to improve performance.