Crash while playing 14w31a

Big One. Killing my server repeatedly. I did not have this issue while running under the same settings/environment in 14w30c.

---- Minecraft Crash Report ----
// Would you like a cupcake?

Time: 7/31/14 3:25 PM
Description: Exception in server tick loop

java.util.ConcurrentModificationException
	at java.util.HashMap$HashIterator.nextEntry(Unknown Source)
	at java.util.HashMap$KeyIterator.next(Unknown Source)
	at qi.a(SourceFile:163)
	at net.minecraft.server.MinecraftServer.y(SourceFile:614)
	at pk.y(SourceFile:303)
	at net.minecraft.server.MinecraftServer.x(SourceFile:530)
	at net.minecraft.server.MinecraftServer.run(SourceFile:446)
	at java.lang.Thread.run(Unknown Source)


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

-- System Details --
Details:
	Minecraft Version: 14w31a
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.7.0_60, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 2116927472 bytes (2018 MB) / 4275044352 bytes (4077 MB) up to 7635730432 bytes (7282 MB)
	JVM Flags: 2 total; -Xms4G -Xmx8G
	IntCache: cache: 1, tcache: 1, allocated: 12, tallocated: 98
	Profiler Position: N/A (disabled)
	Player Count: 1 / 25; [qr['loststory08'/1239425, l='New_Elderwood', x=201.32, y=65.00, z=-90.93]]
	Is Modded: Unknown (can't tell)
	Type: Dedicated Server (map_server.txt)

This bug must be only in the 14w31a snapshot, didn't have the problem anymore after downgrading to 14w30c.

---- Minecraft Crash Report ----
// I blame Dinnerbone.

Time: 7/31/14 8:25 PM
Description: Exception in server tick loop

java.util.ConcurrentModificationException
	at java.util.HashMap$HashIterator.nextEntry(Unknown Source)
	at java.util.HashMap$KeyIterator.next(Unknown Source)
	at qi.a(SourceFile:163)
	at net.minecraft.server.MinecraftServer.y(SourceFile:614)
	at pk.y(SourceFile:303)
	at net.minecraft.server.MinecraftServer.x(SourceFile:530)
	at net.minecraft.server.MinecraftServer.run(SourceFile:446)
	at java.lang.Thread.run(Unknown Source)


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

-- System Details --
Details:
	Minecraft Version: 14w31a
	Operating System: Linux (amd64) version 3.13.11-nitradoV3-MC-300-nH-nP-BF-a
	Java Version: 1.7.0_65, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 127532464 bytes (121 MB) / 288882688 bytes (275 MB) up to 1908932608 bytes (1820 MB)
	JVM Flags: 2 total; -Xmx2048M -Xms256M
	IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94

This crash happens to me too. worked fine yesterday, played for hours without any problems. tried playing again today with the same version and settings, and it crashes ever 45 seconds regardless of what im doing

From what has happened to me it seems to have to do with Zombies in some way, correct me if im wrong

Same happens for me, but the reason seem to be chickens. I attached my crash log.

Awaiting Response, if you experience this issue, please make a comment, otherwise, this will soon be marked as "Fixed".

Please don't close it just yet, in 14w31a, it sometimes took a long time before the issue started appearing.

i think you can mark this as fixed i was just running around in my world for a while and encountered no crashes. I think this might have been fixed

It's not fixed: MC-65556

MC-65556 has nothing to do with this.