Greycat: free more memory during shutdown
diff --git a/greycat/org.eclipse.hawk.greycat/src/org/eclipse/hawk/greycat/AbstractGreycatDatabase.java b/greycat/org.eclipse.hawk.greycat/src/org/eclipse/hawk/greycat/AbstractGreycatDatabase.java
index d9f783e..fc7ae4a 100644
--- a/greycat/org.eclipse.hawk.greycat/src/org/eclipse/hawk/greycat/AbstractGreycatDatabase.java
+++ b/greycat/org.eclipse.hawk.greycat/src/org/eclipse/hawk/greycat/AbstractGreycatDatabase.java
@@ -254,6 +254,19 @@
 			luceneIndexer.shutdown();
 			luceneIndexer = null;
 		}
+
+		currentDirtyNodes.clear();
+		currentOpenNodes.clear();
+
+		if (softDeleteIndex != null) {
+			softDeleteIndex.free();
+			softDeleteIndex = null;
+		}
+
+		if (nodeLabelIndex != null) {
+			nodeLabelIndex.free();
+			nodeLabelIndex = null;
+		}
 	}
 
 	public AbstractGreycatDatabase() {