message: Pre-allocate memory for vectors where size is already known.
diff: @@ -146,6 +146,7 @@ PYBIND11_MODULE(_pywrap_tf_cluster, m) {
  std::vector<tensorflow::OpDef> ops;
  registry->GetRegisteredOps(&ops);
  std::vector<std::string> op_names;
  + op_names.reserve(ops.size());
  for (const tensorflow::OpDef& op : ops) {
  op_names.push_back(op.name());
  }
  