temp change to run tpu test

pytorch_lightning/plugins/training_type/tpu_spawn.py

@@ -32,7 +32,7 @@
 from pytorch_lightning.trainer.connectors.data_connector import DataConnector
 from pytorch_lightning.trainer.states import TrainerFn
 from pytorch_lightning.utilities import _TPU_AVAILABLE, find_shared_parameters, rank_zero_warn, set_shared_parameters
-from pytorch_lightning.utilities.apply_func import move_data_to_device
+from pytorch_lightning.utilities.apply_func import apply_to_collection, move_data_to_device
 from pytorch_lightning.utilities.data import has_len
 from pytorch_lightning.utilities.distributed import rank_zero_only, ReduceOp
 from pytorch_lightning.utilities.exceptions import MisconfigurationException
@@ -127,6 +127,14 @@ def setup(self, trainer: "pl.Trainer") -> None:
             self.setup_optimizers(trainer)
         self.setup_precision_plugin()
 
+    def _move_optimizer_state(self, device: Optional[torch.device] = None) -> None:
+        """Moves the state of the optimizers to the TPU if needed."""
+        # TODO: `self.root_device` would raise error if called outside the spawn process
+        # while training on 8 and more cores.
+        for opt in self.optimizers:
+            for p, v in opt.state.items():
+                opt.state[p] = apply_to_collection(v, torch.Tensor, move_data_to_device, self.root_device)
+
     def _setup_model(self, model: Module) -> Module:
         return model