@Override
  public void testInsertTablets(Map<String, Tablet> tablets, boolean sorted)
      throws IoTDBConnectionException, StatementExecutionException {
    ISession session = getSession();
    try {
      session.testInsertTablets(tablets, sorted);
      putBack(session);
    } catch (IoTDBConnectionException e) {
      // TException means the connection is broken, remove it and get a new one.
      LOGGER.warn("testInsertTablets failed", e);
      cleanSessionAndMayThrowConnectionException(session, FINAL_RETRY, e);
    } catch (StatementExecutionException | RuntimeException e) {
      putBack(session);
      throw e;
    } catch (Throwable e) {
      LOGGER.error("unexpected error in testInsertTablets", e);
      putBack(session);
      throw new RuntimeException(e);
    }
  }
This method NOT insert data into database and the server just return after accept the request,
this method should be used to test other time cost in client
iotdb-client/session/src/main/java/org/apache/iotdb/session/pool/SessionPool.java