private Object executeSyncRequest(
      CnToDnSyncRequestType requestType, SyncDataNodeInternalServiceClient client, Object req)
      throws Exception {
    return Objects.requireNonNull(actionMap.get(requestType)).apply(req, client);
  }
Synchronously send RPC requests to DataNodes. See queryengine.thrift for more details.
iotdb-core/confignode/src/main/java/org/apache/iotdb/confignode/client/sync/SyncDataNodeClientPool.java