diff --git a/src/lightning/pytorch/strategies/launchers/multiprocessing.py b/src/lightning/pytorch/strategies/launchers/multiprocessing.py
index 0d5e47d72e..3e9a2d622f 100644
--- a/src/lightning/pytorch/strategies/launchers/multiprocessing.py
+++ b/src/lightning/pytorch/strategies/launchers/multiprocessing.py
@@ -236,24 +236,11 @@ class _MultiProcessingLauncher(_Launcher):
             process this output.
 
         """
-
-        def tensor_to_bytes(tensor: Tensor) -> bytes:
-            buffer = io.BytesIO()
-            torch.save(tensor.cpu().clone(), buffer)
-            return buffer.getvalue()
-
+        callback_metrics = apply_to_collection(trainer.callback_metrics, Tensor, lambda t: t.cpu())
         # send tensors as bytes to avoid issues with memory sharing
-        # print("callback metrics trainer", trainer.callback_metrics)
-        callback_metrics = {'foo': torch.tensor(3.), 'foo_2': torch.tensor(4.), 'foo_3': torch.tensor(2.), 'foo_4': torch.tensor(1.5000), 'foo_5': torch.tensor(3.),
-         'foo_11': torch.tensor(1.5000), 'foo_11_step': torch.tensor(2.5000), 'bar': torch.tensor(6.), 'bar_2': torch.tensor(1.),
-         'bar_3': torch.tensor(3.), 'foo_6': torch.tensor(9.), 'foo_7': torch.tensor(12.), 'foo_8': torch.tensor(2.), 'foo_9': torch.tensor(1.5000),
-         'foo_10': torch.tensor(2.), 'foo_11_epoch': torch.tensor(1.5000)}
-
         buffer = io.BytesIO()
         torch.save(callback_metrics, buffer)
-        # callback_metrics = apply_to_collection(callback_metrics, Tensor, tensor_to_bytes)
-        # print("callback metrics bytes", callback_metrics)
-        return {"callback_metrics": buffer.getvalue()}
+        return {"callback_metrics_bytes": buffer.getvalue()}
 
     def update_main_process_results(self, trainer: "pl.Trainer", extra: Dict[str, Any]) -> None:
         """Retrieve the :attr:`trainer.callback_metrics` dictionary from the given queue. To preserve consistency, we
@@ -265,14 +252,10 @@ class _MultiProcessingLauncher(_Launcher):
                 on the current trainer.
 
         """
-
-        def bytes_to_tensor(tensor_bytes: bytes) -> Tensor:
-            return torch.load(io.BytesIO(tensor_bytes))
-
         # NOTE: `get_extra_results` needs to be called before
-        callback_metrics = extra["callback_metrics"]
-        print("received callback metrics bytes", callback_metrics)
-        trainer.callback_metrics.update(torch.load(io.BytesIO(callback_metrics))) # apply_to_collection(callback_metrics, bytes, bytes_to_tensor))
+        callback_metrics_bytes = extra["callback_metrics_bytes"]
+        callback_metrics = torch.load(io.BytesIO(callback_metrics_bytes))
+        trainer.callback_metrics.update(callback_metrics)
 
     @override
     def kill(self, signum: _SIGNUM) -> None: