    def broadcast_global_state_dict(self, state_dict):
        """
        Broadcasts a global state dict to all ranks.
        Useful for optimizers that shard state between ranks.
        """
        if hasattr(self.optimizer, "broadcast_global_state_dict"):
            return self.optimizer.broadcast_global_state_dict(state_dict)
        else:
            return state_dict
Broadcasts a global state dict to all ranks.
Useful for optimizers that shard state between ranks.
fairseq/optim/fairseq_optimizer.py