Rewrite accelerator_connector

Author: four4fish

pytorch_lightning/strategies/ddp.py

@@ -80,7 +80,7 @@ class DDPStrategy(ParallelStrategy):
     devices (e.g. GPU) per node. It is very similar to how :mod:`torch.distributed.launch` launches processes.
     """
 
-    distributed_backend = _StrategyType.DDP
+    distributed_backend = "ddp"
 
     def __init__(
         self,
@@ -431,6 +431,11 @@ def register_strategies(cls, strategy_registry: Dict) -> None:
             description="DDP Strategy with `find_unused_parameters` as False",
             find_unused_parameters=False,
         )
+        strategy_registry.register(
+            cls.distributed_backend,
+            cls,
+            description="Strategy",
+        )
 
     def _should_run_deadlock_detection(self) -> bool:
         """Determines whether the plugin will perform process reconciliation in case of errors.

pytorch_lightning/strategies/ddp2.py

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import torch
+from typing import Dict
 
 from pytorch_lightning.strategies.ddp import DDPStrategy
 from pytorch_lightning.utilities.apply_func import apply_to_collection
@@ -22,7 +23,7 @@
 class DDP2Strategy(DDPStrategy):
     """DDP2 behaves like DP in one node, but synchronization across nodes behaves like in DDP."""
 
-    distributed_backend = _StrategyType.DDP2
+    distributed_backend = "ddp2"
 
     @property
     def global_rank(self) -> int:
@@ -73,3 +74,11 @@ def set_world_ranks(self) -> None:
             return
         self.cluster_environment.set_global_rank(self.node_rank)
         self.cluster_environment.set_world_size(self.num_nodes)
+
+    @classmethod
+    def register_strategies(cls, strategy_registry: Dict) -> None:
+        strategy_registry.register(
+            cls.distributed_backend,
+            cls,
+            description="Strategy",
+        )

pytorch_lightning/strategies/ddp_spawn.py

@@ -58,7 +58,7 @@ class DDPSpawnStrategy(ParallelStrategy):
     """Spawns processes using the :func:`torch.multiprocessing.spawn` method and joins processes after training
     finishes."""
 
-    distributed_backend = _StrategyType.DDP_SPAWN
+    distributed_backend = "ddp_spawn"
 
     def __init__(
         self,
@@ -369,6 +369,11 @@ def register_strategies(cls, strategy_registry: Dict) -> None:
             description="DDPSpawn Strategy with `find_unused_parameters` as False",
             find_unused_parameters=False,
         )
+        strategy_registry.register(
+            cls.distributed_backend,
+            cls,
+            description="Strategy",
+        )
 
     def teardown(self) -> None:
         super().teardown()

pytorch_lightning/strategies/deepspeed.py

@@ -82,7 +82,7 @@ def _move_float_tensors_to_half(self, batch: Any):
 
 
 class DeepSpeedStrategy(DDPStrategy):
-    distributed_backend = _StrategyType.DEEPSPEED
+    distributed_backend = "deepspeed"
     DEEPSPEED_ENV_VAR = "PL_DEEPSPEED_CONFIG_PATH"
 
     def __init__(