"Can't keep up" message spam for 35+ players - any tips?

Discussion in 'Bukkit Help' started by gnftoxic, May 11, 2011.

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    I'm looking for some tips on optimizing my Java installation and getting rid of these messages. I'm currently using OpenJDK, however I can easily install Java from their site if someone reports that it has better performance.

    Just information on my server, I'm running an AMD Phenom II x4 (quad core) 965 (3.4 GHz) server with 8GB DDR3 RAM, 500 GB SCSI hard drive on 100Mbit.
    I'm running Ubuntu 10.10 64-bit, running Java in 64-bit mode.
    # uname -a  && java -version
    Linux pwnage.me 2.6.35-22-server #35-Ubuntu SMP Sat Oct 16 22:02:33 UTC 2010 x86_64 GNU/Linux
    java version "1.6.0_20"
    OpenJDK Runtime Environment (IcedTea6 1.9.7) (6b20-1.9.7-0ubuntu1)
    OpenJDK 64-Bit Server VM (build 19.0-b09, mixed mode)
    I'm currently running build #740 (upgrading soon), running only WorldEdit, WorldGuard, Permissions, HomeX, iChat, NoCheat, VanishNoPickup, and Minequery.

    I currently start my server with the following shell file:
    screen -dmS Chaos java -server -d64 \
            -Xmx2G -Xms512M \
            -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:+CMSIncrementalPacing -XX:ParallelGCThreads=2 -XX:+AggressiveOpts \
            -jar craftbukkit.jar
    I've increased the amount of max RAM allocated, moved the world folder to a RAM disk, and tried upping the parallel threads. There is no effect with any of these, just raises the load average with the parallel threads.
    # uptime
     19:02:51 up 4 days, 51 min,  2 users,  load average: 4.18, 3.43, 3.18
    Typical load average is 1.50 - 3.00 (however at peak times [45+ players on a single server] we hit 4.5)

    Any tips would be appreciated, thanks :)
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    Haha, I ask for all this information when I'm helping others outside of minecraft, so it makes it easier to post I guess.

    I haven't tried that, but it looks good. I don't actually know what the "Can't keep up" messages mean - could you explain what it means? I understand the time ran backwards, because it is much more obvious than just "can't keep up." I'm assuming it has something to do with processing stuff as fast as Minecraft wishes for it to (because none of my servers have any lag at all)?

    Edit: Just attempted using that plugin - doesn't work. D:

    Edit 2: Sweet, player count goes to 55-62 as I try to figure out the messages. Not gonna reload plugins for a little bit haha.
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    if the users don't notice or complain of lag, it's safe to ignore.

    There is a plugin called Performance Tweaks that has a few options in it that reduce the amount of chunk writing. Give that a try and see if it makes a difference.
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    I have that running on my Survival server. Seems to work pretty well, but I don't remember why exactly I took it off of this server. I'll see if that fixes anything, thanks.
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    The cant keep up message comes up when the system tries to keep all time relative in game. If for an instance you were to teleport halfway across the map it keeps the same time, simple yes. What happens is if you use teleports, quick travel or anything else that affects time the system experiences a time lag and must re-config to appropraite world time. I hope what i just said actually makes sense.

    That plugin worked for me, hmmm. Whats it say or do when its installed? Have you looked at the thread to see if that can help.
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