code: public void activeClose(TransferContext context, int connections) {
  
          try {
  
              //this could be improved; for symmetry and performance,
              //make it a separate task class and pass to the taskThread
              for (int i = 0; i < connections; i++) {
                  SocketBox sbox = socketPool.checkOut();
                  try {
                      GridFTPDataChannel dc = new GridFTPDataChannel(gSession, sbox);
                      EBlockImageDCWriter writer = (EBlockImageDCWriter)dc.getDataChannelSink(context);
                      writer.setDataStream(sbox.getSocket().getOutputStream());
                      // close the socket
                      writer.close();
                  } finally {
                      // do not reuse the socket
                      socketPool.remove(sbox);
                      sbox.setSocket(null);
                  }
              }
  
          } catch (Exception e) {
              FTPServerFacade.exceptionToControlChannel(
                  e,
                  "closing of a reused connection failed",
                  localControlChannel);
          }
      }
docs: use only in mode E