High CPU Usage

Discussion in 'Bukkit Help' started by ManBearWaffle, Mar 12, 2011.

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    I'm going to leave my post here aswell.
    I used to host my server at home for a month on a very good machine so i had no trouble with performance at all. My connection was bottlenecking me.
    So I have moved the server to a dedicated machine recently, which is hosted on hetzner.
    And here the fun part starts. Server CPU usage is reaching 95% with 8-10 players online and never drops below 50% even when they log out. This results are blocks reappearing and Can't keep up messages. One could easily blame plugins, but disabling ALL of them reduces load on CPU by 3-5% and doesn't solve the problem at all.
    Running vanilla server instead of craftbukkit on the same map reults with 55% CPU load with 15 players online and around 15% when idle. I'm running server from HDD, not from RAMdrive.

    Server details:

    1) Ubuntu 10.04
    2) x64
    java version "1.60_24"
    Java(TM) SE Runtime Environment (build 1.60_24-b07)
    Java HotSpot(TM) 64-bit Server VM (build 19.1-b02, mixed mode)
    4) Not running any wrappers.
    5) Tried both 531 and 556
    6) java -Xmx3072M -Xms3072M -Xincgc -jar minecraft_server.jar nogui
    7) Fair list of plugins, however removing all of them has little to no effect, so not gonna list them here.
    8) No errors apart from Can't Keep Up message
    9) Things i've tried:
    Removing plugins completely
    Using fresh map
    Changing from openjdk to sun java
    Changing java garbage collection options
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    Possibly an important note:

    I'm still running build 566 on Fedora 12 and aside from bukkit's CPU usage, I've had fantastic luck. Yes, 8-10 players causes insane lag, but when everyone logs out, the CPU usage goes right back down to maybe 10% with htop running - so I figure that puts Bukkit (with plugins) running at around 8%.

    Maybe try Fedora?
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    how big is your map? do you have all mobs on? i've been running with bmobs to eradicate squids and so far i've had better luck (of course i also moved to a new beefier VPS).
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    My map is currently about 350 megs with all mobs on. I am, however, running the Mobiile plugin. Squid still spawn at random - BUT - they do not spawn in greater numbers than they would normally in vanilla minecraft. The /butcher command in worldedit never kills off more than maybe 200 or so mobs.
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    Any changes with the latest recommended build?
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    Not on mine sadly, I still get 10% cpu with just me on the Survival map if I've got just animals enabled, same with monsters and animals.

    But soon as I shut them off? Other than the initial spike of load while it opens, it sits at 2-3%.

    It's definitely mob related, and I wouldn't worry if it weren't that I am having issues finding a stable up-to-date plugin that lets them spawn but in much more controlled numbers :(

    Edit: Forgot the normal: AMD Phenom II X4 2.8ghz quad, 4gb ram (1gb allocated to the server); the client is running on the same pc as the server in both tests, client performance did not change but the cpu usage did. Earlier today when another player logged in, the server was hitting 20% cpu; the last time we had 3, everyone disconnected when the server crashed.

    But not when mobs were off; with mobs off, it sits at about 10% if we get all 3 of us on there.
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    Same stuff in 617+ Cpu about 40-40% 20 online. Depending how complex the area is when someone logs off they can cause 100% temp cpu usage for chunk unloading.

    With about 30-35 online it hits about 100% this is of course the main thread on one of the cores. At this point chat and such instant. But things like terrain loading and blocks become laggy.

    i7 2.93ghz 16gigs of ram and I use ramdisk centos 64bit and java 1.7
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    With CB612 and animals turned on, this issue isn't showing up. At least not yet...
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    Nathan C

    Same problem. 10 people and I get lag and "can't keep up" messages.

    CraftBukkit 617. Removing all the plugins doesn't seem to help either.

    Lag seems to happen when people leave and join.

    Specs are:
    - Core 2 Duo E8400 3ghz -- one core just for Minecraft server app
    - 4 Gb DDR2 - World running in RAM
    -100 mbit/s uplink
    -2x 200 Gb 7200 RPM SATA in RAID.
    -Debian 6 (Squeeze)
    -Java 1.6 update 24
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    Same here, before 1.4 update I had 30ppl online and low CPU usage now at 1.4 I have 10ppl online and CPU usage at 85-95%

    Can someone help?
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    No, no cahnges at all.
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    Is this going to be fixed? Its pointless to have serwer for 10 players taking 100% of CPU as before I had 30 players with low CPU usage ;]

    Some of us are running Linux version not windows ;] Linux ftw!
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    with build 617, im getting cant keep up messages with ZERO people connected. Where as before it would be 10-15 before i saw those messages. Double checking to make sure ALL plugins are updated now.
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    WTF is going on with bukkit :(:(
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    I am running linux.. the java params carry over..
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    Since 1.4 I get 100% cpu with 10 players. With monsters turned off I am around 55% with 10 players. It is definitely a mob related issue. I have tested a brand new map and same thing. I also have "Ghost Slime" on this server and im wondering if it is a slime thing. I have area's 2x2x2 block that you cant build on and if you enter you get hurt and die, with the death mod saying you were killed by a slime. They are there with no mods and spawns all turned off. They are persistent as in always in the same place. Something in the chunk file thinks they are still there. There is no way to get rid of them. I would love any solution someone might have, to try and get rid of these ghost slime.
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    Try removing all entities in MCEdit. I'm absolutely sure this problem is mob related, our server caps at 100% CPU with around 10 people on; with mobs off, we hit 18 players at 30% CPU load.
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    And what we should do now? Please fix this issue and try to im prove the Performance. Mojang does nothing in this section :8

    God of Minecraft help us :)
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    I've got pretty much the exact same setup going, and i run fine with around 10 players. Same CPU, amount of RAM, OS and java version. I'm using a tmpfs ramdisk for my worlds though.

    I used to get trouble with my old startup command:
    java -Xmx2G -Xincgc -jar craftbukkit.jar nogui
    Over time the server would reach the 2G mark, and then start lagging when players walked or teleported. The CPU would max out a lot. I read this: http://developer.amd.com/documentation/articles/pages/4easywaystodojavagarbagecollectiontuning.aspx and applied the settings suggested for maximum throughput. CPU spikes when teleporting are now quite small, and performance doesn't decrease over time anymore. This is what im currently using:
    java -Xmn512M -Xms1G -Xmx2G -XX:+UseParallelOldGC -XX:ParallelGCThreads=4 -jar craftbukkit.jar nogui
    I don't have a lot of plugins, but i do have dynmap with all maptypes enabled and a 1 second renderinterval, which is pretty intensive.
  21. Does anyone have a fix for this?
    I'm using a 2GB VPS with quad core processor. and my VPS is using tons of ram. 4.0+ (SunJava 7) where as another server which i assist with uses 0.2-0.3+ (OpenJDK).

    Sunjava was supposed to reduce cpu right?
    My VPS used to work fine until a recent Kernal upgrade in CentOS which fixed lots of issues, but not with my minecraft ;(

    (Also sorry if this is classed as gravedigging, i saw it on google and need an answer :p)
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    Is Sun/Oracle Java 7 even final yet? I thought version 6 was the latest official for *NIX.
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    havent had much luck with g1gc but other then that it works pretty well 8^)
  25. Still no fix for this? i installed ubuntu and had my cpu down to 0.01-0.5 and now its escilated up to about 10!
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