[1.12.2] Cross Dim teleport crashing

[Rakruirn]

Good afternoon, 

 

I hope someone will be able to help me address this issue, its been driving me nuts. 

I've been working on a little cross world teleport command. Not knowing how it was done, I started off by looking around in the existing minecraft/forge code to see what was available. 

As a result I came across this method:
FMLCommonHandler.instance().getMinecraftServerInstance().getPlayerList().transferPlayerToDimension(EntityPlayer, DimID, Teleporter)

After creating my own extended version of Teleporter(copied into a spoiler below), I tried it out and it works... most of the time. When it works, it works great, no issues. However randomly it just kills the client/server with the following error: 

Spoiler

---- Minecraft Crash Report ----
// Quite honestly, I wouldn't worry myself about that.

Time: 11/12/17 1:34 PM
Description: Exception ticking world

java.util.ConcurrentModificationException
   at java.util.LinkedList$ListItr.checkForComodification(LinkedList.java:966)
   at java.util.LinkedList$ListItr.next(LinkedList.java:888)
   at net.minecraft.server.management.PlayerChunkMap.tick(PlayerChunkMap.java:210)
   at net.minecraft.world.WorldServer.tick(WorldServer.java:236)
   at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:829)
   at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:741)
   at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:192)
   at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:590)
   at java.lang.Thread.run(Thread.java:748)


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

-- Head --
Thread: Server thread
Stacktrace:
   at java.util.LinkedList$ListItr.checkForComodification(LinkedList.java:966)
   at java.util.LinkedList$ListItr.next(LinkedList.java:888)
   at net.minecraft.server.management.PlayerChunkMap.tick(PlayerChunkMap.java:210)
   at net.minecraft.world.WorldServer.tick(WorldServer.java:236)

-- Affected level --
Details:
   Level name: New World
   All players: 0 total; []
   Chunk stats: ServerChunkCache: 907 Drop: 625
   Level seed: 4041886264837728842
   Level generator: ID 00 - default, ver 1. Features enabled: true
   Level generator options: 
   Level spawn location: World: (96,64,248), Chunk: (at 0,4,8 in 6,15; contains blocks 96,0,240 to 111,255,255), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
   Level time: 7076 game time, 7076 day time
   Level dimension: -1
   Level storage version: 0x04ABD - Anvil
   Level weather: Rain time: 150310 (now: false), thunder time: 120985 (now: false)
   Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: true
Stacktrace:
   at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:829)
   at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:741)
   at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:192)
   at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:590)
   at java.lang.Thread.run(Thread.java:748)

 

Here is my reduced teleporter: 

Spoiler

public class CrossDimTeleporter extends Teleporter {
    private double x, y, z;

    public CrossDimTeleporter(WorldServer worldIn, double x, double y, double z) {
        super(worldIn);
        this.x = x;
        this.y = y;
        this.z = z;
    }

    @Override
    public void placeInPortal(Entity entityIn, float rotationYaw) {

        //((EntityPlayerMP)entityIn).connection.setPlayerLocation(x, y, z, rotationYaw, 0);
        //entityIn.setLocationAndAngles(this.x, this.y,this.z, 90F, 0.0F);
        entityIn.setPositionAndUpdate(x, y, z);
        entityIn.motionX = 0.0D;
        entityIn.motionY = 0.0D;
        entityIn.motionZ = 0.0D;

    }
}

As you can see I've tried different methods of the actual movement of the player. 

 

As I understand it, the error is due to a sudden change in a list that is being iterated over, however I don't have a clue on how to work around or resolve that. 

Any help would be appreciated. 

 

My target version of forge right now is: 1.12.2-14.23.0.2491

[Rakruirn]

Thinking about this more... could this be happening if the teleport command isn't on the main thread?

[tebreca]

are you adding this functionality to a block or an item?

or just for a command?

 

[Rakruirn]

More or less a command.

The reason I have it on a different thread is due to what I'm trying to do. My goal is to be able to run this teleport command from outside of minecraft.

I have a Netty listener receiving and parsing input. This is being run on another thread to not block the normal game flow. That part works as far as I know.

It listens for a specific trigger and executes the 

FMLCommonHandler.instance().getMinecraftServerInstance().getPlayerList().transferPlayerToDimension(EntityPlayer, DimID, Teleporter) command passing in the desired coordinates to the Teleporter class I listed in my first post. 

[cmchenry]

Was this ever resolved? I'm still having this issue.