message: Protect the creation of the graph, which loads the runtime codelets
diff: @@ -264,9 +264,10 @@ StatusOr<std::unique_ptr<Executable>> PoplarCompiler::RunBackend(
  const poplar::Device& dev = poplarExecutor->GetPoplarDevice();
  - poplar::Graph* graph = new poplar::Graph(dev);
  + poplar::Graph* graph;
  {
  std::lock_guard <std::mutex> g(static_mu_);
  + graph = new poplar::Graph(dev);
  graph->addCodelets(GetPathToGraphProgFile());
  popconv::addCodelets(*graph);
  popnn::addCodelets(*graph);
  