A Basic Explanation of session.lock

[OmniSapien]

Can anyone explain to me how session.lock works and how to avoid getting it to throw an Exception? I've been having a lot of issues lately because I am saving data into a custom file in the current world's save file. If a stack trace is needed, it is below:

 

[iNFO] [sTDERR] net.minecraft.world.MinecraftException: The save is being accessed from another location, aborting
[iNFO] [sTDERR] 	at net.minecraft.world.storage.SaveHandler.checkSessionLock(SaveHandler.java:104)
[iNFO] [sTDERR] 	at net.minecraft.world.World.checkSessionLock(World.java:4001)
[iNFO] [sTDERR] 	at net.minecraft.world.chunk.storage.AnvilChunkLoader.saveChunk(AnvilChunkLoader.java:120)
[iNFO] [sTDERR] 	at net.minecraft.world.gen.ChunkProviderServer.safeSaveChunk(ChunkProviderServer.java:232)
[iNFO] [sTDERR] 	at net.minecraft.world.gen.ChunkProviderServer.unload100OldestChunks(ChunkProviderServer.java:328)
[iNFO] [sTDERR] 	at net.minecraft.world.WorldServer.tick(WorldServer.java:166)
[iNFO] [sTDERR] 	at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:668)
[iNFO] [sTDERR] 	at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:598)
[iNFO] [sTDERR] 	at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:123)
[iNFO] [sTDERR] 	at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:497)
[iNFO] [sTDERR] 	at net.minecraft.server.ThreadMinecraftServer.run(ThreadMinecraftServer.java:16)