@Override
            public Thread newThread(Runnable r) {
                Thread th = new Thread(r);
                th.setName("jME TerrainGrid Thread");
                th.setDaemon(true);
                return th;
            }
This will print out any exceptions from the thread
jme3-terrain/src/main/java/com/jme3/terrain/geomipmap/TerrainGrid.java