What does this error mean?

Discussion in 'Spigot Help' started by malon, May 15, 2016.

  1. So I keep getting "concurrentModificationExceptions" but I'm not sure why, so I've included 3 crash logs and the surrounding code around it, but it doesn't seem related to me. Is it likely a plugin issue? How can I figure out which plugin if so?

    Code (Text):

    [04:13:05] [Server thread/INFO]: Greek05 issued server command: //brush sphere quarts 4
    [04:13:08] [Server thread/INFO]: Greek05 issued server command: //brush sphere quarts 4
    [04:13:10] [Async Chat Thread - #32/INFO]: [0;37;22m{[0;37;1m[0;32;22m1.9[0;37;1m[0;37;22m} [m[0;37;22m([0;31;22mFl[0;33;1ma[0;31;22msh[0;37;22m) Shady1003[m[0;37;22m: [0;33;1mrecording for the trailer[m
    [04:13:16] [Async Chat Thread - #32/INFO]: [0;37;22m{[0;37;1m[0;33;22mF[0;37;1m[0;37;22m} [m[0;37;22m([0;36;1mD[0;36;22mo[0;36;1mct[0;36;22mo[0;36;1mr [0;36;1mM[0;36;22ma[0;36;1mnhatt[0;36;22ma[0;36;1mn[0;37;22m) ~[0;32;1mT[0;32;22me[0;32;1mk[0;32;22mt[0;32;1mr[0;32;22mo[0;32;1mn[0;32;22mi[0;32;1mc[m[0;37;22m: [0;36;1mokay[m
    [04:13:17] [Async Chat Thread - #32/INFO]: [0;37;22m{[0;37;1m[0;32;22m1.9[0;37;1m[0;37;22m} [m[0;37;22m([0;31;22mFl[0;33;1ma[0;31;22msh[0;37;22m) Shady1003[m[0;37;22m: [0;33;1mthats why i put the ...[m
    [04:13:43] [Server thread/ERROR]: Encountered an unexpected exception
    java.util.ConcurrentModificationException
        at java.util.HashMap$HashIterator.nextNode(HashMap.java:1429) ~[?:1.8.0_91]
        at java.util.HashMap$KeyIterator.next(HashMap.java:1453) ~[?:1.8.0_91]
        at net.minecraft.server.v1_9_R2.EntityTracker.updatePlayers(EntityTracker.java:193) ~[spigot.jar:git-Spigot-4af49dc-23da8b0]
        at net.minecraft.server.v1_9_R2.MinecraftServer.D(MinecraftServer.java:814) ~[spigot.jar:git-Spigot-4af49dc-23da8b0]
        at net.minecraft.server.v1_9_R2.DedicatedServer.D(DedicatedServer.java:399) ~[spigot.jar:git-Spigot-4af49dc-23da8b0]
        at net.minecraft.server.v1_9_R2.MinecraftServer.C(MinecraftServer.java:665) ~[spigot.jar:git-Spigot-4af49dc-23da8b0]
        at net.minecraft.server.v1_9_R2.MinecraftServer.run(MinecraftServer.java:564) [spigot.jar:git-Spigot-4af49dc-23da8b0]
        at java.lang.Thread.run(Thread.java:745) [?:1.8.0_91]
    [04:13:43] [Server thread/ERROR]: This crash report has been saved to: /home/minecraft/server/./crash-reports/crash-2016-05-15_04.13.43-server.txt
    [04:13:43] [Server thread/INFO]: Stopping server
     
    Code (Text):

    [04:13:43] [Server thread/ERROR]: Encountered an unexpected exception
    java.util.ConcurrentModificationException
        at java.util.HashMap$HashIterator.nextNode(HashMap.java:1429) ~[?:1.8.0_91]
        at java.util.HashMap$KeyIterator.next(HashMap.java:1453) ~[?:1.8.0_91]
        at net.minecraft.server.v1_9_R2.EntityTracker.updatePlayers(EntityTracker.java:193) ~[spigot.jar:git-Spigot-4af49dc-23da8b0]
        at net.minecraft.server.v1_9_R2.MinecraftServer.D(MinecraftServer.java:814) ~[spigot.jar:git-Spigot-4af49dc-23da8b0]
        at net.minecraft.server.v1_9_R2.DedicatedServer.D(DedicatedServer.java:399) ~[spigot.jar:git-Spigot-4af49dc-23da8b0]
        at net.minecraft.server.v1_9_R2.MinecraftServer.C(MinecraftServer.java:665) ~[spigot.jar:git-Spigot-4af49dc-23da8b0]
        at net.minecraft.server.v1_9_R2.MinecraftServer.run(MinecraftServer.java:564) [spigot.jar:git-Spigot-4af49dc-23da8b0]
        at java.lang.Thread.run(Thread.java:745) [?:1.8.0_91]
    [04:13:43] [Server thread/ERROR]: This crash report has been saved to: /home/minecraft/server/./crash-reports/crash-2016-05-15_04.13.43-server.txt
    [04:13:43] [Server thread/INFO]: Stopping server
     
    Code (Text):

    [22:52:17] [Server thread/INFO]: Tektronic lost connection: Disconnected
    [22:52:17] [Server thread/INFO]: Tektronic left the game.
    [22:52:19] [Server thread/INFO]: [email protected][id=<null>,name=Tektronic,properties={},legacy=false] (/173.21.210.12:50727) lost connection: Disconnected
    [22:52:21] [Server thread/INFO]: Christheking2004 issued server command: /disguise player TheGamingLakeYT
    [22:52:25] [Server thread/ERROR]: Encountered an unexpected exception
    java.util.ConcurrentModificationException
        at java.util.HashMap$HashIterator.nextNode(HashMap.java:1429) ~[?:1.8.0_91]
        at java.util.HashMap$KeyIterator.next(HashMap.java:1453) ~[?:1.8.0_91]
        at net.minecraft.server.v1_9_R2.EntityTracker.updatePlayers(EntityTracker.java:193) ~[spigot.jar:git-Spigot-4af49dc-23da8b0]
        at net.minecraft.server.v1_9_R2.MinecraftServer.D(MinecraftServer.java:814) ~[spigot.jar:git-Spigot-4af49dc-23da8b0]
        at net.minecraft.server.v1_9_R2.DedicatedServer.D(DedicatedServer.java:399) ~[spigot.jar:git-Spigot-4af49dc-23da8b0]
        at net.minecraft.server.v1_9_R2.MinecraftServer.C(MinecraftServer.java:665) ~[spigot.jar:git-Spigot-4af49dc-23da8b0]
        at net.minecraft.server.v1_9_R2.MinecraftServer.run(MinecraftServer.java:564) [spigot.jar:git-Spigot-4af49dc-23da8b0]
        at java.lang.Thread.run(Thread.java:745) [?:1.8.0_91]
    [22:52:25] [Server thread/ERROR]: This crash report has been saved to: /home/minecraft/server/./crash-reports/crash-2016-05-13_22.52.25-server.txt
    [22:52:25] [Server thread/INFO]: Stopping server
     
     
  2. I'd guess it's a corrupt chunk. First thing to do is make a backup. You could then try programs like Minecraft Region Fixer or Void Chunk and see if they find any errors. You could also try finding out where a player entered when the crash occurred, then go there and see if it happens to you.
     
  3. I've scanned all my worlds using Minecraft Region Fixer. It's definitely not chunk related because it only seems to happen with at least 4 people are online. We've all been in spawn and it just seems to randomly happen. Spawn is a world by itself that is 100% empty apart from a 200x200 area. Since there are only a few chucks with blocks in them inside of spawn, that means 100% of all non-air blocks in the entire world are loaded when any player is in spawn, unless chunks composed entirely of air can be corrupt? Even so, I scanned that world too, no errors.

    Every plugin, everything on my server is guaranteed 100% the latest dev versions available. Same with 1.8 Java builds and Ubuntu updates.

    How can I debug what's causing this?

    Code (Text):

    ---- Minecraft Crash Report ----
    // Ooh. Shiny.

    Time: 5/28/16 4:03 PM
    Description: Exception in server tick loop

    java.util.ConcurrentModificationException
            at java.util.HashMap$HashIterator.nextNode(HashMap.java:1429)
            at java.util.HashMap$KeyIterator.next(HashMap.java:1453)
            at net.minecraft.server.v1_9_R2.EntityTracker.updatePlayers(EntityTracker.java:176)
            at net.minecraft.server.v1_9_R2.MinecraftServer.D(MinecraftServer.java:814)
            at net.minecraft.server.v1_9_R2.DedicatedServer.D(DedicatedServer.java:399)
            at net.minecraft.server.v1_9_R2.MinecraftServer.C(MinecraftServer.java:665)
            at net.minecraft.server.v1_9_R2.MinecraftServer.run(MinecraftServer.java:564)
            at java.lang.Thread.run(Thread.java:745)


    A detailed walkthrough of the error, its code path and all known details is as follows:
    ---------------------------------------------------------------------------------------

    -- System Details --
    Details:
            Minecraft Version: 1.9.4
            Operating System: Linux (amd64) version 4.5.3-x86_64-linode67
            Java Version: 1.8.0_91, Oracle Corporation
            Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
            Memory: 275116704 bytes (262 MB) / 1032847360 bytes (985 MB) up to 3817865216 bytes (3641 MB)
            JVM Flags: 2 total; -Xms512M -Xmx4096M
            IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
            CraftBukkit Information:
       Running: CraftBukkit version git-Spigot-8a048fe-106ced0 (MC: 1.9.4) (Implementing API version 1.9.4-R0.1-SNAPSHOT) true
       Plugins: { CleanroomGenerator v1.0.0 io.nv.bukkit.CleanroomGenerator.CleanroomGenerator [NVX (Neo_Vortex)], CoreProtect v2.12.0 net.coreprotect.CoreProtect [Intelli], AsyncWorldEditInjector v3.3.5 org.primesoft.asyncworldedit.injector.InjectorBukkit [SBPrime], LastLog v1.1.1 edu.self.startux.lastLog.LastLogPlugin [StarTux], OpenInv v2.3.8 com.lishid.openinv.OpenInv [lishid, ShadowRanger], CommandHelper v3.3.2-SNAPSHOT.3121- com.laytonsmith.commandhelper.CommandHelperPlugin [], CrackShot v0.98.5 com.shampaggon.crackshot.CSDirector [Shampaggon], PowerNBT v0.8.6.1 me.dpohvar.powernbt.PowerNBT [DPOH-VAR], Multiverse-Core v2.5.0-SNAPSHOT-b722 com.onarandombox.MultiverseCore.MultiverseCore [Rigby, fernferret, lithium3141, main--], ProtocolLib v4.0.1 com.comphenix.protocol.ProtocolLib [dmulloy2, comphenix], AutoSaveWorld v4.15.dev autosaveworld.core.AutoSaveWorld [_Shevchik_], LibsDisguises v9.0.6-SNAPSHOT me.libraryaddict.disguise.LibsDisguises [libraryaddict, Byteflux, Navid K.], BCC v0.5.5 info.trentech.BCC.BCC [], CrackShotPlus v0.22 me.DeeCaaD.CrackShotPlus.Commands [DeeCaaD], AsyncWorldEdit v3.3.9 org.primesoft.asyncworldedit.AsyncWorldEditMain [SBPrime], SuperTrails v9.5.1 me.kvq.plugin.trails.main [kvq], VoxelSniper v5.171.0-SNAPSHOT com.thevoxelbox.voxelsniper.VoxelSniper [przerwap, MikeMatrix, Gavjenks, giltwist, psanker, Deamon5550, DivineRage], EditableSign v2.2.0 com.vk2gpz.editablesign.EditableSign [vk2gpz], PermissionsEx v1.23.4 ru.tehkode.permissions.bukkit.PermissionsEx [[t3hk0d3, zml]], ParticleLIB v2.1.0 org.inventivetalent.particle.ParticlePlugin [inventivetalent], Timer v0.001 com.gmail.malonnnnn.timer.Timer [], Multiverse-NetherPortals v2.5.0-SNAPSHOT-b712 com.onarandombox.MultiverseNetherPortals.MultiverseNetherPortals [Rigby, fernferret], Vault v1.5.6-b49 net.milkbowl.vault.Vault [cereal, Sleaker, mung3r], WorldEdit v6.1.3-SNAPSHOT;3547-fd0e400 com.sk89q.worldedit.bukkit.WorldEditPlugin [], AntiXRay v1.8.5 me.ryanhamshire.AntiXRay.AntiXRay [blablubbabc, bigscary, blablubbabc], Essentials v2.0.1-b345 com.earth2me.essentials.Essentials [Zenexer, ementalo, Aelux, Brettflan, KimKandor, snowleo, ceulemans, Xeology, KHobbits, md_5, Iaccidentally, drtshock, vemacs], CrackLaser v1.4.8 me.Porama6400.CrackLaser.CrackLaser [], ObsidianAuctions v4.0.2 com.flobi.floauction.FloAuction [flobi, VirusTotal], PerWorldInventory v1.7.4 me.gnat008.perworldinventory.PerWorldInventory [Gnat008], HolographicDisplays v2.1.13 com.gmail.filoghost.holographicdisplays.HolographicDisplays [], SignShop v2.11.0Dev org.wargamer2010.signshop.SignShop [Wargamer2010 and Devinish], WorldGuard v6.1.2-SNAPSHOT;1664-5bd2125 com.sk89q.worldguard.bukkit.WorldGuardPlugin [], PreventShare v1.0.1 com.ninjaguild.preventshare.PreventShare [NinjaStix], Citizens v2.0.18-SNAPSHOT (build 1369) net.citizensnpcs.Citizens [aPunch, fullwall], OnTime v4.1.4 me.edge209.OnTime.OnTime [Edge209], VanishNoPacket v3.20 org.kitteh.vanish.VanishPlugin [mbaxter], EssentialsProtect v2.0.1-b345 com.earth2me.essentials.protect.EssentialsProtect [Zenexer, ementalo, Aelux, Brettflan, KimKandor, snowleo, ceulemans, Xeology, KHobbits], EssentialsChat v2.0.1-b345 com.earth2me.essentials.chat.EssentialsChat [Zenexer, ementalo, Aelux, Brettflan, KimKandor, snowleo, ceulemans, Xeology, KHobbits, md_5, Okamosy, Iaccidentally], EssentialsAntiBuild v2.0.1-b345 com.earth2me.essentials.antibuild.EssentialsAntiBuild [Zenexer, ementalo, Aelux, Brettflan, KimKandor, snowleo, ceulemans, Xeology, KHobbits, Iaccidentally], EssentialsSpawn v2.0.1-b345 com.earth2me.essentials.spawn.EssentialsSpawn [Zenexer, ementalo, Aelux, Brettflan, KimKandor, snowleo, ceulemans, Xeology, KHobbits], GriefPrevention v14.6 me.ryanhamshire.GriefPrevention.GriefPrevention [],}
       Warnings: DEFAULT
       Reload Count: 0
     
     
    #3 malon, May 28, 2016
    Last edited: May 28, 2016
  4. Code (Text):

    [02:24:01] [Async Chat Thread - #79/INFO]: [0;37;22m{[0;37;1m[0;32;22m1.9[0;37;1m[0;37;22m} [m[0;37;22m([0;32;22mMar[0;34;1mt[0;32;22mian [0;34;1mMan[0;32;22mhunter[0;37;22m) Converse_Boy[m[0;37;22m: [0;32;22mget your disguise into some fights and let it get hurt then go to the actual tek and youll see him[m
    [02:24:04] [Server thread/INFO]: [0;37;22m{[0;37;1m[0;32;22m1.9[0;37;1m[0;37;22m} [m[0;37;22m([0;32;22mMar[0;34;1mt[0;32;22mian [0;34;1mMan[0;32;22mhunter[0;37;22m) Converse_Boy[m[0;37;22m: [0;32;22myour just a sillow wet of a perfect man... u,take me higher[m
    [02:24:05] [Async Chat Thread - #79/INFO]: [0;37;22m{[0;37;1m[0;32;22m1.9[0;37;1m[0;37;22m} [m[0;37;22m([0;32;22mMar[0;34;1mt[0;32;22mian [0;34;1mMan[0;32;22mhunter[0;37;22m) Converse_Boy[m[0;37;22m: [0;32;22mwith the same injuries[m
    [02:24:18] [Server thread/ERROR]: Encountered an unexpected exception
    java.util.ConcurrentModificationException
        at java.util.HashMap$HashIterator.nextNode(HashMap.java:1429) ~[?:1.8.0_91]
        at java.util.HashMap$KeyIterator.next(HashMap.java:1453) ~[?:1.8.0_91]
        at net.minecraft.server.v1_9_R2.EntityTracker.updatePlayers(EntityTracker.java:193) ~[spigot.jar:git-Spigot-8a048fe-71e5248]
        at net.minecraft.server.v1_9_R2.MinecraftServer.D(MinecraftServer.java:814) ~[spigot.jar:git-Spigot-8a048fe-71e5248]
        at net.minecraft.server.v1_9_R2.DedicatedServer.D(DedicatedServer.java:399) ~[spigot.jar:git-Spigot-8a048fe-71e5248]
        at net.minecraft.server.v1_9_R2.MinecraftServer.C(MinecraftServer.java:665) ~[spigot.jar:git-Spigot-8a048fe-71e5248]
        at net.minecraft.server.v1_9_R2.MinecraftServer.run(MinecraftServer.java:564) [spigot.jar:git-Spigot-8a048fe-71e5248]
        at java.lang.Thread.run(Thread.java:745) [?:1.8.0_91]
    [02:24:18] [Server thread/ERROR]: This crash report has been saved to: /home/minecraft/server/./crash-reports/crash-2016-05-30_02.24.18-server.txt
    [02:24:18] [Server thread/INFO]: Stopping server
     
    Full Crash Report
    http://pastebin.com/Zfz2ka6S
     
  5. Waaaaay too many plugins.

    It looks like something involving an invalid player, or asynchronous access to player data. Probably a bad plugin.
     
  6. Saw comments online that this can be caused by a plugin doing things it's not allowed to in an async thread. Try removing as many plugins as you can, then add them back bit by bit to isolate the cause.
     
  7. The error "ConcurrentModificationException" is when an asynchronous thread is trying to modify something in the main thread at the same time as something else. Basically, as said above this is caused by a plugin using the Bukkit API on an async thread when it shouldn't be.

    You'd have to look through your plugins and probably remove any that could be causing this issue, looks like the plugin in question is trying to do something with players.
     
    • Agree Agree x 1
  8. Okay, I've started the debugging process of disabling as many plugins as possible and figuring out one-by-one what the deal is.

    In the meantime (cuz this could take weeks) is it possible that two plugins are interfering with each other? What I mean is...is it possible for the error to occur when PluginA && PluginB are installed at the same time, but wouldn't happen if PluginA || PluginB installed? Or is this likely only a situation between RandomPlugin and spigot?
     
  9. What does this plugin do?
    Timer v0.001 com.gmail.malonnnnn.timer.Timer
     
  10. A player steps on a pressure plate and it saves the current server timestamp in a hashmap. Then they step on a 2nd pressure plate and it subtracts the current time from 1st pressure plate step to give the elapsed time.

    Simply put, It's a mechanism that will tell you the elapsed time between stepping on two different pressure plates. I've since lost the source code to that plugin, but I will happily provide you with the jar so you can decompile it (I'm the author, obviously).

    I ran that plugin all throughout 1.8 but this issue has only cropped up since 1.9. I'm not a great plugin author, but it's a really simple plugin. You think it could be my shitty coding?

    Here's the jar
    https://drive.google.com/file/d/0BwzYOs4Ch_hGajR1OXVPd0Rqd0U/view?usp=sharing