code: public synchronized void shutdown() {
  		if (instances.size() > 0) {
  			OLogManager.instance().debug(null,
  					"Found %d databases opened during OrientDB shutdown. Assure to always close database instances after usage",
  					instances.size());
  
  			for (ODatabaseComplex<?> db : new HashSet<ODatabaseComplex<?>>(instances.keySet())) {
  				if (db != null && !db.isClosed()) {
  					db.close();
  				}
  			}
  		}
  	}
docs: Closes all open databases.