code: private void probeChannel() {
      if (isStopped()) return;
  
      try {
        if (selector.selectNow() > 0) {
          final Iterator<SelectionKey> iterator = selector.selectedKeys().iterator();
  
          while (iterator.hasNext()) {
            final SelectionKey key = iterator.next();
            iterator.remove();
  
            if (key.isValid()) {
              if (key.isAcceptable()) {
                accept(key);
              }
            }
          }
        }
      } catch (Exception e) {
        e.printStackTrace();
        logger().log("Failed to accept client channel for '" + name + "' because: " + e.getMessage(), e);
      }
    }
docs: =========================================