Windows .exe DW20 Strange Java Error every 30'ish seconds

[inctor]

Hey all,

I am running a Direwolf20 server for me and my friends, it has 6gb RAM allocated for 3 players, which should be more than enough as far as i can tell.

However, i'm getting a strange JavaError, that doesn't crash the server, just fills up my error logs and i cant seem to find the issue at hand.

This is the error that occurs once in a while;
2013-07-11 08:01:32 [INFO] [STDERR] java.util.ConcurrentModificationException
2013-07-11 08:01:32 [INFO] [STDERR] at java.util.HashMap$HashIterator.nextEntry(Unknown Source)
2013-07-11 08:01:32 [INFO] [STDERR] at java.util.HashMap$ValueIterator.next(Unknown Source)
2013-07-11 08:01:32 [INFO] [STDERR] at bq.a(SourceFile:24)
2013-07-11 08:01:32 [INFO] [STDERR] at cd.a(SourceFile:114)
2013-07-11 08:01:32 [INFO] [STDERR] at ca.a(CompressedStreamTools.java:140)
2013-07-11 08:01:32 [INFO] [STDERR] at aam.a(AnvilChunkLoader.java:198)
2013-07-11 08:01:32 [INFO] [STDERR] at aam.c(AnvilChunkLoader.java:184)
2013-07-11 08:01:32 [INFO] [STDERR] at aiw.b(SourceFile:29)
2013-07-11 08:01:32 [INFO] [STDERR] at aiw.run(SourceFile:22)
2013-07-11 08:01:32 [INFO] [STDERR] at java.lang.Thread.run(Unknown Source)

I've tried to google it, without much luck.

All i can see, that it is prolly Chunk Loader related.

Although we have very few chunk loaders in the game, 1 in Nether and 2 in over world keeping a maximum of 50 chunks loaded total.

Does any of you know a solution to this, or is it a common bug?