*  * org.apache.lucene.queryParser.!ParseException: Cannot parse !'': Encountered "<EOF>" at line 1, column 0.
   * https://issues.apache.org/jira/browse/LUCENE-881
 * http://stackoverflow.com/questions/2272908/java-io-filenotfoundexception-too-many-open-files
   * !http://stackoverflow.com/questions/2272908/java-io-filenotfoundexception-too-many-open-files