High CPU Usage

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

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    I used the bmobs plugin, and i also have butcher.. doesn't provide instant gratification but, it seems a few hours after wiping out the mobs a few times using both commands.. my CPU usage settled into a reasonable and acceptable range of 30%-40% which I'll take.. not as good as it once was but, it's operable.. I may be giving this bkill command to my moderators so they can use it as necessary. Once every few hours or so at this time. Is there any plugins that can search for your map for problems also?? I'm wondering if some of this issues could be related to any map or chunk correction, or recalculations. The map I'm using right now is actually restored from a backup... I'm wondering if there may be corruption involved, and if anyone else with high CPU is also using a map derived from a backup.. if we can find some commonality to our issue - we may be able to derive a solution.
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    Pre-531 I was able to run a server with 8 people, no problem. Currently:

    Bukkit Version: 556

    AMD x64 Dual core - 2.4 Ghz.
    2GB DDR2

    OS: Fedora 12 Linux.
    Java: Sun Java 1.6.0_24

    Interesting Places
    Magic Carpet
    Login Message
    Stats & Achievements
    Heroic Death

    Even without plugins installed once I get up to 6 players on line at once, the CPU is banging up on 100% and spewing "Can't keep up!" messages. Adding plugins accounts for a mere 10% utilization increase. Seems that the CPU load increases dramatically with each player that joins. Watching my utilization with a mere two players results in an average of 60% utilization :(

    Oddly enough, I don't have any RAM issues whatsoever. Slowly creeps up until about 1.7 Gigs and then stops. Doesn't even touch swap.
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    i havent found ram usage to be a problem at all with the server, running 20-30 people garbage collections happen nicely. unnoticeable.
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    i guess we've all kind of hit the wall on this issue for now. i just keep hoping that the next bukkit recommended build will magically fix this.
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    I may have found some ways to help. Mobs are certainly part of the problem. I use World Edit /butcher command, kills 1000 mobs.. they disappear.. then more mobs take their place. The spawn rate is very high, and a way to limit a total mob count would be nice.. something light weight.. the existing mob control plugins are not as efficient or as effective as I would like to see regarding this one issue.

    Another thing I have found.. in the Essentials Plugin, there is an option to reclaim memory on user logout.. that seems to be having a positive effect for my server. I've also been forced to cap down player total.. not the greatest option in the world but, prefer a stable server over one with players that crashes alot.
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    Same issue with 556 recommended build. 100% with 3 players mobs on. Was around 75% with 6 players prior to CraftBukkit and mobs were on.

    Oddly though, when I first installed CraftBukkit with Essentials, rTriggers, and MinecartMania (all but autocart) CPU usage was under 25%.. 2 players in the same area.. we went exploring together, and it went up and stayed at around 60% we came back and stood still for a few minutes and it still stays at that rate.. now, even on an empty server, it idles at around 25%. Not experiencing lag, because I believe TOP combines the load of both cores.. so one core maxed would show 100% add 25% to the second core, it will show 125% or 2 cores at 50% would show 100%.. not sure on this.

    Either way, seems like CraftBukkit is being overly demanding.. this is my first install of CraftBukkit since hMod died at v1 of beta MC.
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    I had the same thing with the squids and seem to of fixed it by

    1. Stop server
    2. set spawns to false
    3. start server without bukkit and the affected chunks should be running smooth.
    4. Save & close world.
    5. Turn spawns back then start with bukkit.

    I didnt read whole thread for a fix so If this was posted already sorry.
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    so you are saying the squids are spawning rampantly, and it's best to disable them, restart, save, enable and it should relax for a bit?
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    Like some of the others in this thread I had the issue where in a few chunks there were hundreds of squid causing anyone getting close to or warping to that chunk would completely lag out. I tried to just disable the animals but with bukkit the squid would still load and cause problems until I loaded my map without bukkit and saved it with out animals. Now I turned on animals with bukkit and server is running perfectly.
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    Totally worth a try. Thanks for responding. To sum it up:

    Stop server.
    Disable Mobs.
    Start WITHOUT Bukkit and mobs.
    Force save.
    Stop Server.
    Turn on animals.
    Start server with Bukkit.

    Trying right now.
    Tried it, CPU at idle dropped to single digits, though with 2 players on, CPU usage goes up to AT LEAST 60%.. 3.0GHz dualcore.
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    Yeah, it seems that my problem is the same. The CPU ramps up dramatically with each player connected. I've seen some squid spawn here and there, but nothing like what I've seen you folks reporting. Using the /butcher command only kills off maybe a couple hundred mobs and effectively does nothing for the CPU usage.
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    Today and yesterday have been quite a lot new builds. Have anyone tested them?
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    no, i might. i'm worried cause it looks like lots of handlings are changed. afraid a lot of plugins will break. i might experiment though.

    yea anything past 560 will break world guard and world edit because of the major changes in event handling involving items and block damage. will try 560 though.

    EDIT by Moderator: merged posts, please use the edit button instead of double posting.
    Last edited by a moderator: May 12, 2016
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    That shouldn't be a problem, as you should always be testing without plugins, right?
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    Heh. Just a warning for anyone wanting to start up bukkit without mods. Remember worldguard can stop firespread. If you disable worldguard and load up without mods, alot of things may burn to the ground.

    I run a server with 50 people at peak time. I have done months and months of research to get the server to be able to handle that many people. Yes, there are periods where it lags, but for the most part, pickup lag and chat lag is pretty good (less than 1 second,) but the sun/moon lag is pretty bad with 50+ on. With 30 players, everything is ok.

    I have noticed the server completely locking up here and there. I never knew about the massive amount of squids spawning and this concerns me. I think i'm going to write a plugin that outputs all the Entities and their locations to a text file to see if this is the issue.

    Good to see this discussion on the board.
    LlmDl likes this.
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    Well, obviously have a backup of your world before testing. Its easily enough done - have one folder as your main CB folder, one folder as your test. When testing, shut down primary server, copy world over, start up test server - have users connect. Everything can be the same except the test server has no plugins or other mods/wrappers being used.
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    yea actually i did run into this problem once without worldGuard. oops. everything is a lesson.
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    Going on what was discussed here, I decided to make a quick plugin function that looped through all the worlds, and all the entities in the world and display them to a text file called mobs.txt:

    The output can be found here:

    http://thunderdome-mc.com/mobs.txt (158kb)

    This is 3 minutes after a reboot with about 30 players on.

    You will notice that there are quite a few squids and they are all grouped together. After 3 mins :p I couldn't imagine after 12 hours. I'll rerun in an hour as well.
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    Odd we have never had spawns and we still get CPU issues haha..
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    Good work. Looks like a squid REDUCING plugin is in order. Something that can actually limit their spawns.. or at the least, kill a few as they spawn based on the area they spawn at etc...
    LlmDl likes this.
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    You know what... take a look on your maps. My is 1Gb

    Server without any plugins and without any players and spawn mobs turned off on build 493...


    I think that map reduction will help a lot of you ;)
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    That's without any players?
    My map is like 2GB, and with no players, CPU is 0%.
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    I've tested on completely new maps... CPU is still high. This is a minecraft issue though I can confirm now, I am having serious troubles so I left bukkit altogether for now.. I started a fresh temp map on a plain jane vanilla installation... and I'm getting 40+% CPU usage on that with a 10 player limit after an hour of uptime on a brand new map.

    I can't afford to get a vps upgrade or go dedicated... so well, if the goal here was to thin out the server owners (which I know alot want to do) .. you're probably looking at one less here.

    - I did have some small success running my world in vanilla, saving, stopping and restarting in bukkit. The server sat idle, playerless at 5% CPU for a few minutes. Then, once player 1 logged in... 23%. Been waiting for player 2 to login for several hours now.. lol.. but when your server is offline for 2 days.. generally you lose everyone.
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    You can use htop to figure out the load of individual threads and cores, it also has a nice little interface. :)
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    An update to my post.. after about an hour and up to 5 players.. CPU has come up to 37%. What is not promising is that it doesn't scale back down when players log out.
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    thx, keep us updated.

    I just started running a xeon 2.0GHz Dell Precision 530 pos server(current bukkit, current plugins, etc). and I need each and every performance tweak available. I can't get ubuntu to recognize the video but thats not the issue(downloading ubuntu server now to try). So anyways its running on xp(tweaked for performance as much as xp can be).

    - First off should I put Windows2000p on it? I know it uses less RAM than XP but would java and Minecraft run as good on it?
    - 2nd, I've gone as far as removing mobs from the server to increase performance... (I'll add item dispensers for the leather/cotton/etc if I have to.... :/ ) Any good suggestions? I'm willing to sacrifice some things for performance. I was also thinking of just having cows and zombies....
    (I'm trying to find scsi drives for it so I can raid it. For some reason a simple ide-raid0 on this POS isn't easily possible. I have more options to configure my personal desktop lawl).

    So yeah, i need any old trick you might be able to tell me. I've seen somthing about TnT's performance guide but I can't find it and it might be old.... Links anything.

    THANK YOU!!!! :)
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    Check the links in my sig, they're up to date.
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    I've been on 3 separate servers testing this. All using Ubuntu 10.10, but with different hardware. It's been the same story every time.

    Currently we're on a 4GB VDS hosted by allgamer.net -running Ubuntu 10.10, Java 6 x64. We cap out at 20-24 players because of 100% CPU usage. (with lag and tons of "can't keep up!")

    WorldEdit, WorldGuard, CommandBook, GroupManager (With  FakePermissions), MyHome, MyWarp, TelePlus, LWC, HeroChat, SpawnControl,  GuestPrev, EpicZones, PreciousStones, iConomy, iConomyChestShop,  HeroBounty, DropBonus, Help 
    CB 566 with the same world, no plugins = 20-40%CPU usage at 4-6 players
    CB 566 with the same world, all plugins = 30-45%CPU usage at 4-6 players
    CB 566 with a new world, no plugins = 1-15%CPU usage at 4-6 players (usually stays low)
    CB 566 with a new world, all plugins = 5-20%CPU usage at 4-6 players (usually stays low)
    Vanilla server with the same world, = 10-40%CPU usage at 4-5 players (hovers around 15% but spikes often Now with 7 players its hovering around 35-50%CPU)

    Our old world is around 600MB. What if it is fire? I let people use flint&steel because WG stops fire, it's been like that for awhile now. I see fireplaces and other things almost everywhere.

    How intensive is fire on a server? I'm going to download the world and go to town in MCEdit and see if it reduces CPU load at all.
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    Really appreciate the info guys. I haven't had time to read through all of these yet but I will as soon as I can :)
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