@Override
  public SettableFuture<ConfigTaskResult> showFunctions(Model model) {
    SettableFuture<ConfigTaskResult> future = SettableFuture.create();
    try (ConfigNodeClient client =
        CONFIG_NODE_CLIENT_MANAGER.borrowClient(ConfigNodeInfo.CONFIG_REGION_ID)) {
      TGetUDFTableResp getUDFTableResp = client.getUDFTable(new TGetUdfTableReq(model));
      if (getUDFTableResp.getStatus().getCode() != TSStatusCode.SUCCESS_STATUS.getStatusCode()) {
        future.setException(
            new IoTDBException(
                getUDFTableResp.getStatus().message, getUDFTableResp.getStatus().code));
        return future;
      }
      // convert UDFTable and buildTsBlock
      ShowFunctionsTask.buildTsBlock(model, getUDFTableResp.getAllUDFInformation(), future);
    } catch (ClientManagerException | TException e) {
      future.setException(e);
    }

    return future;
  }
FIXME Consolidate this clientManager with the upper one.
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/queryengine/plan/execution/config/executor/ClusterConfigTaskExecutor.java