Encountered an unexpected exception

[19:04:44] [Server thread/ERROR]: Encountered an unexpected exception
net.minecraft.util.ReportedException: Exception ticking world
	at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:631) ~[MinecraftServer.class:?]
	at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:334) ~[lt.class:?]
	at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:547) ~[MinecraftServer.class:?]
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:427) [MinecraftServer.class:?]
	at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:685) [li.class:?]
Caused by: java.lang.OutOfMemoryError: PermGen space
	at java.lang.Class.getDeclaredConstructors0(Native Method) ~[?:1.7.0_67]
	at java.lang.Class.privateGetDeclaredConstructors(Unknown Source) ~[?:1.7.0_67]
	at java.lang.Class.getConstructor0(Unknown Source) ~[?:1.7.0_67]
	at java.lang.Class.newInstance(Unknown Source) ~[?:1.7.0_67]
	at sun.reflect.MethodAccessorGenerator$1.run(Unknown Source) ~[?:1.7.0_67]
	at sun.reflect.MethodAccessorGenerator$1.run(Unknown Source) ~[?:1.7.0_67]
	at java.security.AccessController.doPrivileged(Native Method) ~[?:1.7.0_67]
	at sun.reflect.MethodAccessorGenerator.generate(Unknown Source) ~[?:1.7.0_67]
	at sun.reflect.MethodAccessorGenerator.generateConstructor(Unknown Source) ~[?:1.7.0_67]
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source) ~[?:1.7.0_67]
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source) ~[?:1.7.0_67]
	at java.lang.reflect.Constructor.newInstance(Unknown Source) ~[?:1.7.0_67]
	at net.minecraft.world.SpawnerAnimals.func_77192_a(SpawnerAnimals.java:159) ~[aho.class:?]
	at net.minecraft.world.WorldServer.func_72835_b(WorldServer.java:161) ~[mt.class:?]
	at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:625) ~[MinecraftServer.class:?]
	... 4 more
[19:04:45] [Server thread/INFO]: Stopping server
[19:04:46] [Server thread/ERROR]: Exception stopping the server
java.lang.NoClassDefFoundError: io/netty/channel/DefaultChannelHandlerContext$14
	at io.netty.channel.DefaultChannelHandlerContext.close(DefaultChannelHandlerContext.java:547) ~[DefaultChannelHandlerContext.class:?]
	at io.netty.channel.DefaultChannelHandlerContext.close(DefaultChannelHandlerContext.java:423) ~[DefaultChannelHandlerContext.class:?]
	at io.netty.channel.DefaultChannelPipeline.close(DefaultChannelPipeline.java:826) ~[DefaultChannelPipeline.class:?]
	at io.netty.channel.AbstractChannel.close(AbstractChannel.java:177) ~[AbstractChannel.class:?]
	at net.minecraft.network.NetworkSystem.func_151268_b(NetworkSystem.java:132) ~[nc.class:?]
	at net.minecraft.server.MinecraftServer.func_71260_j(MinecraftServer.java:337) ~[MinecraftServer.class:?]
	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:480) [MinecraftServer.class:?]
	at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:685) [li.class:?]
Caused by: java.lang.ClassNotFoundException: io.netty.channel.DefaultChannelHandlerContext$14
	at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191) ~[launchwrapper-1.11.jar:?]
	at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.7.0_67]
	at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.7.0_67]
	... 8 more
Caused by: java.lang.OutOfMemoryError: PermGen space
	at java.lang.ClassLoader.defineClass1(Native Method) ~[?:1.7.0_67]
	at java.lang.ClassLoader.defineClass(Unknown Source) ~[?:1.7.0_67]
	at java.security.SecureClassLoader.defineClass(Unknown Source) ~[?:1.7.0_67]
	at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:182) ~[launchwrapper-1.11.jar:?]
	at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.7.0_67]
	at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.7.0_67]
	... 8 more