OutOfBounds Causing Server Crash

My server continues to crash on the same exception every time in my WorldWarZ plugin I have created:

Code:

# ftServer.java:457) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2979jnks]
at net.minecraft.server.v1_7_R1.ThreadServerApplication.run(SourceFile:617) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2979jnks]
[19:27:40] [Server thread/INFO]: TPS: 13.0Free Memory: 1683MB
[19:27:40] [Server thread/WARN]: [WorldWarZ] Task #33606260 for WorldWarZ v2.4 generated an exception
java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
at java.util.ArrayList.rangeCheck(ArrayList.java:604) ~[?:1.7.0_17]
at java.util.ArrayList.get(ArrayList.java:382) ~[?:1.7.0_17]
at Memory.MemoryManagement$MemoryChecker.run(MemoryManagement.java:60) ~[?:?]
at org.bukkit.craftbukkit.v1_7_R1.scheduler.CraftTask.run(CraftTask.java:53) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2979jnks]
at org.bukkit.craftbukkit.v1_7_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:345) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2979jnks]
at net.minecraft.server.v1_7_R1.MinecraftServer.u(MinecraftServer.java:587) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2979jnks]
at net.minecraft.server.v1_7_R1.DedicatedServer.u(DedicatedServer.java:250) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2979jnks]
at net.minecraft.server.v1_7_R1.MinecraftServer.t(MinecraftServer.java:545) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2979jnks]
at net.minecraft.server.v1_7_R1.MinecraftServer.run(MinecraftServer.java:457) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2979jnks]
at net.minecraft.server.v1_7_R1.ThreadServerApplication.run(SourceFile:617) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2979jnks]
[19:27:40] [Server thread/INFO]: TPS: 13.0Free Memory: 1683MB
[19:27:40] [Server thread/WARN]: [WorldWarZ] Task #33606261 for WorldWarZ v2.4 generated an exception
java.lang.IndexOutOfBoundsException: Index: 0, Size: 0
at java.util.ArrayList.rangeCheck(ArrayList.java:604) ~[?:1.7.0_17]
at java.util.ArrayList.get(ArrayList.java:382) ~[?:1.7.0_17]
at Memory.MemoryManagement$MemoryChecker.run(MemoryManagement.java:60) ~[?:?]
at org.bukkit.craftbukkit.v1_7_R1.scheduler.CraftTask.run(CraftTask.java:53) ~[craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2979jnks]
at org.bukkit.craftbukkit.v1_7_R1.scheduler.CraftScheduler.mainThreadHeartbeat(CraftScheduler.java:345) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2979jnks]
at net.minecraft.server.v1_7_R1.MinecraftServer.u(MinecraftServer.java:587) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2979jnks]
at net.minecraft.server.v1_7_R1.DedicatedServer.u(DedicatedServer.java:250) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2979jnks]
at net.minecraft.server.v1_7_R1.MinecraftServer.t(MinecraftServer.java:545) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2979jnks]
at net.minecraft.server.v1_7_R1.MinecraftServer.run(MinecraftServer.java:457) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2979jnks]
at net.minecraft.server.v1_7_R1.ThreadServerApplication.run(SourceFile:617) [craftbukkit.jar:git-Bukkit-1.7.2-R0.2-3-g530fcb7-b2979jnks]

Why does an exception as simple as this crash the server? Thanks.

 

spy85 Its not the exception, its the number of tasks you have scheduled
Snippet of the stacktrace

Code:

 Task #33606260 for WorldWarZ v2.4 generated an exception

You have over 33million tasks scheduled.....

 

Not to mention the error is quite clear:

Due to the change, and lack, of package naming, I can only assume "Memory.MemoryManagement" is your plugin. Which, if it is, I suggest you look at package naming conventions as well.

 

Doesn't a task stop and go away once its finished? I mean I have tasks going every few mili seconds and repeating themselves within themselves so that makes sense. Thanks so much I'll fix it!

By the way is it possible to use wait(long) in a BukkitTask or Thread.sleep(long) ?

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

spy85
Nope. Unless you want to freeze your server.

 

What happens to a BukkitRunnable or BukkitTask that I do not cancel? Apparently I have over 3million bukkit tasks running so by canceling them when they're done would this stop the tasks being at 3million? Because I have tasks repeating over and over.

 

It depends. Without the source code, no one can say for certain.

 

The ID is not reused, but usually when you hit 33 million you are doing something weird/wrong.

^ Will indeed help in identifying the issue(s), such as the 33 million tasks.

 

turt2live @ Sagacious_Zed Gater12
Here is an example of one of the many tasks I have in use:

Code:java

    private final int voteCancelSecs = 28;
    private int passedSecs = 0;
    private void repeatVoteTimeLeft(){
        if(voteIsOn){
            new VoteTimeLeft().runTaskLater(plugin, 20*1);
        }
    }
    private class VoteTimeLeft extends BukkitRunnable {
        public void run(){
            passedSecs += 1;
            if(passedSecs >= voteCancelSecs && voteIsOn){
                plugin.getServer().broadcastMessage(chatPrefix + ChatColor.RED + ChatColor.BOLD + "Vote for next round has timed out!");
                endVote();
            }else if(voteIsOn){
                repeatVoteTimeLeft();
            }
        }
    }

What other source code do you need? This is the format in which I run BukkitRunnables usually and repeat them. What am I doing wrong that could be causing 33million? Some BukkitRunnables work the same way as this but repeat every few miliseconds.

 

You create a new task every 1 second so long as "voteIsOn" is true.

 

Right so when I'm done with a task how do I completely remove it so they don't keep adding up and eventually ending up as 33 mil? Will just cancling it at the end work?

 

Yes, if you cancel them you won't end up with that many.

 

It doesn't matter, as long as you create a new one, the counter will increment. For example, even if task #1 is destroyed, you have already created task #2.

 

Is it mandatory that you cancel a task when done with it? What does canceling actually do though?

Right but if I do not cancel the task #1 then task #1 and task #2 combined make 2 tasks but if I do cancel task #1 then there is just task #2 which makes 1 task is that how it will work? So Basically canceling tasks when done with them will do the trick?

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

Looking at it, it might not even be the cancelling. You're just creating so many tasks...is that the only code related to tasks?

 

It depends.
If you run #1 later, it will execute once later creating task #2, then finish.
In this particular case, #2 will run once, creating #3 then finishes.
so on and so forth.

If you run #1 later on a timer, it will execute once creating tasks #2, then put back onto the schedule.
In this particular case, #2 executes once,create task #3 then finishes.
and task #1 will make #4 when it executes as scheduled.
and #3 will created task #5
and so on and so forth.

there is currently not enough context.

 

spy85 You asked a question that I didn't see answered. Just to clarify, it is not necessary to cancel a BukkitRunnable if you are using runTaskLater (or runTask) AFTER it's execution. cancel will stop it before it's execution or is used to stop runTaskTimer. The Bukkit scheduler guide even shows an example of a non-self cancelling Anonymous BukkitRunnable. Since it's anonymous and doesn't cancel itself, there would be no way to get rid of it! Except it really does send itself to garbage collection.

I think the reason you have so many is just because of the sheer number of tasks your scheduling.

 

Oh thank you so much for your help and explanation that really helps! I do not start or even create all the threads at once and usually don't even save them in variables so how could there be 3 million all at once? I understand if 3 million have been created total but 3 million at once doesn't make any sense. Any idea how this happens?

I have tons of classes each with plenty of Tasks but definitely not enough for 33 million.

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

I would assume with a number like that it's something recursive that's multiplying the amount constantly.

 

This particular use case doesn't need so many threads though...