}
    }
  }
}
```
The code here is simple, given the local_ready_queue assigned to each thread in thread-local storage. The threads loop until there are no tasks left to execute in the graph. Note that for device-associated threads, the passed graph_task argument is nullptr, and they block in local_ready_queue->pop() until a task is pushed in their queue. After some consistency checks (the task type is shutdown, or the graph is still valid). We get to the actual function invocation in evaluate_function.
```c++
        try {
          GraphTaskGuard guard(local_graph_task);
          NodeGuard ndguard(task.fn_);
          {
            evaluate_function(
                local_graph_task,
                task.fn_.get(),
                task.inputs_,
                local_graph_task->cpu_ready_queue_);
          }
        } catch (std::exception& e) {