High CPU usage by CraftBukkit under FreeBSD 8.1

Discussion in 'Bukkit Help' started by Pricetx, Nov 17, 2011.

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  1. As the title suggests, I am having issue with high CPU utilisation using CraftBukkit under FreeBSD 8.1. Information is provided below.

    Below is the output of "uname -a && java -version":

    FreeBSD [DOMAIN ADDRESS REMOVED] 8.1-RELEASE FreeBSD 8.1-RELEASE #0: Mon Jul 19 02:36:49 UTC 2010

    [email protected]:/usr/obj/usr/src/sys/GENERIC amd64
    java version "1.6.0_03-p4"
    Java(TM) SE Runtime Environment (build 1.6.0_03-p4-root_12_oct_2010_03_13-b00)
    Java HotSpot(TM) 64-Bit Server VM (build 1.6.0_03-p4-root_12_oct_2010_03_13-b00, mixed mode)

    4. Are you running any wrappers? McMyAdmin, mcadmin, Hamachi, etc?


    5. What build of CraftBukkit are you running? (do NOT say latest. Say the build number.)

    I am running CraftBukkit build #1337, I will additionally paste the server.log entry for it below:

    Craftbukkit version git-Bukkit-0.0.0-1131-g86b7fa8-b1337jnks (MC: 1.8.1)

    6. What command are you using to run your CraftBukkit server?

    -Xincgc -Xmx2G -Xss32m -XX:+DisableExplicitGC -jar

    7. What plugins are you running?

    This issue occurs without any plugins installed.

    8. What error are you getting (post your server.log file)?

    I am not receiving any errors.

    9. What have you tried already?

    I have tried the following startup parameters, all to no avail:

    -Xmx1536M -Xms256M -Xss24m -XX:MaxHeapFreeRatio=90 -XX:+UseParallelGC -XX:parallelGCThreads=4 -XX:MaxGCPauseMillis=450 -jar

    -Xmx1024M -Xms256M -Xss32m -XX:MaxHeapFreeRatio=90 -XX:+UseParallelGC -XX:parallelGCThreads=4 -XX:MaxGCPauseMillis=450 -verbose:GC -Xloggc:gc.log -jar

    -Xmx2048M -Xms256M -Xss32m -XX:+UseConcMarkSweepGC -XX:+UseParNewGC -XX:parallelGCThreads=1 -XX:+CMSParallelRemarkEnabled -XX:+DisableExplicitGC -XX:MaxGCPauseMillis=500 -XX:SurvivorRatio=8 -XX:TargetSurvivorRatio=90 -verbose:GC -Xloggc:gc.log -jar"

    -Xincgc -Xmx2G -Xss32m -XX:+DisableExplicitGC -jar"

    I have tried the following CraftBukkit Builds:

    I have tried both with and without plugins, I have the same issue, therefore plugins aren't the issue.

    I have tried using two blank worlds, and my pre-existing world.

    10. Have you tried any of the things below?

    Run the vanilla Minecraft server (no Craftbukkit)

    I tried this, the CPU usage is far lower than with craftbukkit running. Two people flying on creative mode on vanilla uses less CPU than one person stood still on craftbukkit.

    Update your CraftBukkit Build:

    As stated above, I have tried with three seperate builds of CraftBukkit, included the latest RB.

    Remove all your plugins and try with just CraftBukkit. Does the error/problem still occur:

    Yes, I have tested both with and without plugins, and there is no noticable change in CPU usage.

    Update your plugins:

    Irrelevant considering the post above.

    Add in a single plugin:

    Also Irrelevant considering two posts above.

    Additional information:

    The server has the following CPU:
    Intel(R) Core(TM)2 Quad CPU Q9650 @ 3.00GHz

    When a single player logs on to the Minecraft server, the cpu usage is around 15-20%, and for every player who joins, an extra 5-10% is added to the CPU load. In constrast, with vanilla minecraft, it idles at around 11% CPU, and each player adds around 2% to the CPU. I will hopefully be able to add more useful figures to this section in the near future.
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    Your java seems to be quite old with Version 6, update 3. According to java.com, the latest Recommended Build is Verson 6, Update 29. I'm not at all versed in FreeBSD, so select whichever type of installation file you'd need (my guess would be either Linux or Apple, but I'm sure you'd know better than I would) and see how that treats resources. It's a long-shot, since the high CPU usage is not happening with the vanilla server. But who knows, there could be some feature of Bukkit that's relying on some java function that's better implemented in a later update.

    The only other thing I'd try would be to run it without any GC options, just java -jar CraftBukkit.jar, see if that affects CPU usage at all.
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    Actually, go ahead to java 1.7 if you can, when it came out, it was a major improvement ~10-20% difference. Try without -Xms and possibly without -Xincgc (it's supposed to be less efficient, but happen periodically rather than waiting to fill the ram)
  4. Hello and thanks for your replies.

    Unfortunately, the BSD port of Java is fairly out of date. The latest version available is 6 update 3. However, this version continues to remain supported and has been updated beyond the version I have on my server at the moment. Unfortunately I do not have root access to my server but I may enquire into getting it updated to the latest version to see if that makes a difference.

    Also, I have tried running the server with just "java -jar" and it didn't have any noticeable effect on CPU usage.

    If anybody has any other ideas or suggestions I would be grateful to hear them.
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