Hi, I've taken three 1.6.1 dev builds and all have given me very high CPU usage with relatively low player counts. I am maxxing out one core on a beefy Linux box. I get the message : [WARNING] Can't keep up! Did the system time change, or is the server overloaded? System info: 8-core processor (Intel(R) Xeon(R) CPU E3-1270 V2 @ 3.50GHz) (I know the server load will not exploit them all) 32 GB RAM, 25000 dedicated to my main server, which runs under mcmyadmin. Currently using 1.6.1 dev build 2805 Plugins (39): GroupManager, WorldEdit, BukkitCompat, Buycraft, CCLogger, Vault, PlotMe, Multiverse-Core, LogBlock, ChatGuard, WorldGuard, MineBackup, QuickSign, PuppyVet, iConomy, ReportRTS, Permissions, BanManager, ChunkSpawnerLimiter, Votifier, Skillz, ButtonWarp, Essentials, Residence, ServerSigns, EssentialsSpawn, Multiverse-Inventories, Multiverse-NetherPortals, EssentialsAntiBuild, ResidenceSigns, dynmap, DynmapPlotMe, OnTime, ChestShop, ResProtect, EssentialsChat, BattleArena, WorldBorder, AntiCheat Yes, that's a lot of plugins it could be a compatibility issue. I am seeing 100% processor use on one core (as measured with top/htop) with as few as 8 players logged on - and one of them is my own account, standing at spawn). Previously with 20 users we would use about 30% of one core.
>> Perhaps the computer is dusty or need some more fan power, most likely the cpu is over heating. Err, this is an almost brand-new machine (or so they told us) run by a professional hosting company in a data centre. I am pretty sure the fans are on 24/7 and pretty deafening, but why would running the fans make the CPU usage high, and why on only one of the eight cores? >> Q_Q Or, 1.6.1 is just bugged. It is still in development. Yes, I am hoping this is the answer and so things will get better in a week or so >> What happens when you remove all plugins? I can't do that on this server, as players will lose protection of their builds. I *can* try it on the test server, which runs on the same box with "only" 5G of RAM. I will try this today and invite a couple of players across, but I have a couple of things to do first (like get our new web site live).
bLanark Only one core, because Minecraft is mostly single threaded. Along with plugins. Also, ChunkSpawnerLimiter is horrible when you have the nearby chunk range too high. Try replace it with MobManager Also you could try run /timings That will find out whats using up all your CPU time.
>> Maybe people on your server are exploring new chunks in hope of finding horses? We use worldborder, the world has all been generated >> Also, ChunkSpawnerLimiter is horrible when you have the nearby chunk range too high. Try replace it with MobManager thanks for the hint, will look into it later. We have surroundingRadius set to 2 which is not too high, I hope >> Also you could try run /timings That will find out whats using up all your CPU time. Aha! Something I've never heard of! Will look into this immediately. Thanks. Looks like all my time is used by bukkit itself, even after running for an hour, only 3 plugins have a total time of more than one second, and all less than 10 seconds. (Worldguard (1s), Residence (2s) and AntiCheat (4s) ) EDIT by Moderator: merged posts, please use the edit button instead of double posting.
That's still 23 chunks that the plugin has to check. 23 calls to fetch 23 chunks, then it has to go through each chunk and count all the entities inside of it. To get those entities, it has to create 23 new list objects (Creating new objects in Java is pretty slow) And it does all that every time a mob spawns (If I remember correctly) That isn't what is important. You should look at the average times. You can use up to 50ms of CPU time per tick before you start getting TPS drops. If you paste your timings file to here http://paste.ubuntu.com/ you can get a much better view of your timings via http://aikar.co/timings.php
Ivan You should link some good ones. WarmRoast by sk89q, the creator of WorldEdit and WorldGuard, is a good one. http://forums.bukkit.org/threads/warmroast-a-jvm-cpu-sampling-tool-to-figure-out-why-a-mc-server-lags.153336/
Same issue here, 1 core pegged at 100%, mostly during nighttime. And most likely due to the new zombie spawning mechanic. As soon as night is over that core drops back down to manageable levels. This is on a windows server though.
Profile it to check, if you want to be certain. Though we don't support dev builds of any version, so it's not like it'll help if it's already been reported.
Sorry for not acknowledging the replies, I have been away. I will have a go with the profiler, glad (in a way) that it has been reported by other people too.