@Override
  public SettableFuture<ConfigTaskResult> showConfigNodes() {
    final SettableFuture<ConfigTaskResult> future = SettableFuture.create();
    TShowConfigNodesResp showConfigNodesResp = new TShowConfigNodesResp();
    try (final ConfigNodeClient client =
        CONFIG_NODE_CLIENT_MANAGER.borrowClient(ConfigNodeInfo.CONFIG_REGION_ID)) {
      showConfigNodesResp = client.showConfigNodes();
      if (showConfigNodesResp.getStatus().getCode()
          != TSStatusCode.SUCCESS_STATUS.getStatusCode()) {
        future.setException(
            new IoTDBException(
                showConfigNodesResp.getStatus().message, showConfigNodesResp.getStatus().code));
        return future;
      }
    } catch (final ClientManagerException | TException e) {
      future.setException(e);
    }
    // build TSBlock
    ShowConfigNodesTask.buildTSBlock(showConfigNodesResp, future);
    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