private void checkReloadConf() {
        WatchKey wk;
        wk = watcher.poll();
        
        if (wk == null) {
            return;
        }
        
        for (WatchEvent<?> event : wk.pollEvents()) {
            //we only register "ENTRY_MODIFY" so the context is always a Path.
            final Path changed = (Path) event.context();
            System.out.println(changed);
            if (configuration_filename.endsWith(changed.getFileName().toString())) {
                // reload configuration
                configurationParse();
            }
        }
        // reset the key
        wk.reset();
    }