Hmmm

src/main/java/com/volmit/iris/gen/CeilingChunkGenerator.java

@@ -47,6 +47,7 @@ public abstract class CeilingChunkGenerator extends PostBlockChunkGenerator
 		ceilingCached = false;
 		cacheCeiling = null;
 		cacheFloor = null;
+		getCache().targetChunk(0, 0);
 	}
 
 	private void targetFloor()

src/main/java/com/volmit/iris/gen/atomics/AtomicMulticache.java

@@ -102,4 +102,8 @@ public class AtomicMulticache {
 	public void updateHeight(int x, int z, int h) {
 		height.put(pos(x, z), (double) h);
 	}
+
+	public double getSize() {
+		return height.size();
+	}
 }