code: private void initMerger() throws IOException
     {
        if (merger == null)
        {
           merger = new IndexMerger(this);
           merger.setMaxMergeDocs(handler.getMaxMergeDocs());
           merger.setMergeFactor(handler.getMergeFactor());
           merger.setMinMergeDocs(handler.getMinMergeDocs());
  
           for (Object index : indexes)
           {
              merger.indexAdded(((PersistentIndex)index).getName(), ((PersistentIndex)index).getNumDocuments());
           }
           merger.start();
        }
     }
docs: Initialize IndexMerger.