private String logForReconnectionFailure() {
    if (endPointList == null) {
      return MSG_RECONNECTION_FAIL;
    }
    StringJoiner urls = new StringJoiner(",");
    for (TEndPoint end : endPointList) {
      StringJoiner url = new StringJoiner(":");
      url.add(end.getIp());
      url.add(String.valueOf(end.getPort()));
      urls.add(url.toString());
    }
    return MSG_RECONNECTION_FAIL.concat(urls.toString());
  }
reconnect if the remote datanode is unreachable retry if the status is set to needRetry
iotdb-client/session/src/main/java/org/apache/iotdb/session/SessionConnection.java