[BugFix] Resolve manual optimization

pytorch_lightning/accelerators/accelerator.py

@@ -15,6 +15,7 @@
 
 import torch
 from torch.optim import Optimizer
+from torch.utils.data import DataLoader
 
 from pytorch_lightning.core import LightningModule
 from pytorch_lightning.plugins.precision import (
@@ -228,8 +229,8 @@ def predict(self, args):
         return self.training_type_plugin.predict(*args)
 
     def process_dataloader(
-        self, dataloader: Union[Iterable, torch.utils.data.DataLoader]
-    ) -> Union[Iterable, torch.utils.data.DataLoader]:
+        self, dataloader: Union[Iterable, DataLoader]
+    ) -> Union[Iterable, DataLoader]:
         """Wraps the dataloader if necessary
 
         Args:
@@ -240,7 +241,7 @@ def process_dataloader(
     def backward(
         self,
         closure_loss: torch.Tensor,
-        optimizer: torch.optim.Optimizer,
+        optimizer: Optimizer,
         opt_idx: int,
         should_accumulate: bool,
         *args,
@@ -254,17 +255,17 @@ def backward(
             opt_idx: the index of the optimizer
             should_accumulate: whether to accumulate gradients
         """
-        self.training_type_plugin.pre_backward(closure_loss, optimizer, opt_idx)
+        self.training_type_plugin.pre_backward(closure_loss, should_accumulate, optimizer, opt_idx)
 
         output = self.precision_plugin.backward(
             self.lightning_module, closure_loss, optimizer, opt_idx, should_accumulate, *args, **kwargs
         )
 
-        self.training_type_plugin.post_backward(closure_loss, optimizer, opt_idx)
+        self.training_type_plugin.post_backward(closure_loss, should_accumulate, optimizer, opt_idx)
 
         return output
 
-    def optimizer_step(self, optimizer: torch.optim.Optimizer, opt_idx: int, lambda_closure: Callable, **kwargs):
+    def optimizer_step(self, optimizer: Optimizer, opt_idx: int, lambda_closure: Callable, **kwargs):
         """performs the actual optimizer step.
 
         Args:
@@ -273,33 +274,23 @@ def optimizer_step(self, optimizer: torch.optim.Optimizer, opt_idx: int, lambda_
             lambda_closure: closure calculating the loss value
 
         """
-
-        self.precision_plugin.pre_optimizer_step(optimizer, opt_idx)
-        self.training_type_plugin.pre_optimizer_step(optimizer, opt_idx)
-
-        if isinstance(self.precision_plugin, ApexMixedPrecisionPlugin):
-            # apex does not support passing a closure to the optimizer, call it by itself
-            lambda_closure()
-            lambda_closure = None
-
-        optimizer.step(closure=lambda_closure, **kwargs)
-
+        make_optimizer_step = self.precision_plugin.pre_optimizer_step(
+            self.lightning_module, optimizer, opt_idx, lambda_closure, **kwargs)
+        if make_optimizer_step:
+            self.run_optimizer_step(optimizer, opt_idx, lambda_closure, **kwargs)
         self.precision_plugin.post_optimizer_step(optimizer, opt_idx)
-        self.training_type_plugin.post_optimizer_step(optimizer, opt_idx)
 
-        if self.rpc_enabled and self.training_type_plugin.is_main_rpc_process:
-
-            # Initialize optimizer step on main process
-            self.training_type_plugin.worker_optimizer_step(model=self.lightning_module, opt_idx=opt_idx, **kwargs)
+    def run_optimizer_step(self, optimizer: Optimizer, optimizer_idx: int, lambda_closure: Callable, **kwargs):
+        optimizer.step(closure=lambda_closure, **kwargs)
 
     def optimizer_zero_grad(
-        self, current_epoch: int, batch_idx: int, optimizer: torch.optim.Optimizer, opt_idx: int
+        self, current_epoch: int, batch_idx: int, optimizer: Optimizer, opt_idx: int
     ) -> None:
         """Zeros all model parameter's gradients"""
         model_ref = self.lightning_module
         model_ref.optimizer_zero_grad(current_epoch, batch_idx, optimizer, opt_idx)
 
-    def clip_gradients(self, optimizer: torch.optim.Optimizer, clip_val: Union[int, float]) -> None:
+    def clip_gradients(self, optimizer: Optimizer, clip_val: Union[int, float]) -> None:
         """clips all the optimizer parameters to the given value"""
 
         self.precision_plugin.clip_gradients(optimizer, clip_val)

pytorch_lightning/accelerators/tpu.py

@@ -1,6 +1,6 @@
 from typing import Callable
 
-import torch
+from torch.optim import Optimizer
 
 from pytorch_lightning.accelerators.accelerator import Accelerator
 from pytorch_lightning.plugins.precision import MixedPrecisionPlugin
@@ -26,20 +26,5 @@ def setup(self, trainer, model):
             raise MisconfigurationException("TPUs only support a single tpu core or tpu spawn training.")
         return super().setup(trainer, model)
 
-    def optimizer_step(self, optimizer: torch.optim.Optimizer, opt_idx: int, lambda_closure: Callable, **kwargs):
-        """performs the actual optimizer step.
-
-        Args:
-            optimizer: the optimizer performing the step
-            opt_idx: index of the current optimizer
-            lambda_closure: closure calculating the loss value
-
-        """
-
-        self.precision_plugin.pre_optimizer_step(optimizer, opt_idx)
-        self.training_type_plugin.pre_optimizer_step(optimizer, opt_idx)
-
+    def run_optimizer_step(self, optimizer: Optimizer, optimizer_idx: int, lambda_closure: Callable, **kwargs):
         xm.optimizer_step(optimizer, optimizer_args={'closure': lambda_closure, **kwargs})
-
-        self.precision_plugin.post_optimizer_step(optimizer, opt_idx)
-        self.training_type_plugin.post_optimizer_step(optimizer, opt_idx)

pytorch_lightning/plugins/base_plugin.py

@@ -12,8 +12,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import contextlib
+from torch.nn import Module
 from abc import ABC, abstractmethod
-from typing import Any, Generator, Optional, overload, Sequence, Tuple
+from typing import Any, Callable, Generator, Optional, overload, Sequence, Tuple
 
 import torch
 
@@ -22,18 +23,12 @@ class Plugin(ABC):
     """Basic Plugin class to derive precision and training type plugins from."""
 
     @abstractmethod
-    def connect(self, model: torch.nn.Module, *args: Sequence,
-                **kwargs: Sequence) -> Optional[Tuple[torch.nn.Module, Sequence, Sequence]]:
+    def connect(self, model: Module, *args: Sequence,
+                **kwargs: Sequence) -> Optional[Tuple[Module, Sequence, Sequence]]:
         """Connects the plugin with the accelerator (and thereby with trainer and model).
         Will be called by the accelerator.
         """
 
-    def pre_optimizer_step(self, optimizer: torch.optim.Optimizer, optimizer_idx: int) -> None:
-        """Hook to do something before each optimizer step."""
-
-    def post_optimizer_step(self, optimizer: torch.optim.Optimizer, optimizer_idx: int) -> None:
-        """Hook to do something after each optimizer step."""
-
     def pre_training(self) -> None:
         """Hook to do something before the training starts."""
 

pytorch_lightning/plugins/precision/native_amp.py

@@ -12,9 +12,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 from contextlib import contextmanager
-from typing import Generator
+from typing import Callable, Generator
 
 import torch
+from torch.optim import LBFGS, Optimizer
 
 from pytorch_lightning.core import LightningModule
 from pytorch_lightning.plugins.precision.mixed import MixedPrecisionPlugin
@@ -33,25 +34,11 @@ def __init__(self):
         self.backend = AMPType.NATIVE
         self.scaler = torch.cuda.amp.GradScaler()
 
-    def pre_optimizer_step(self, optimizer: torch.optim.Optimizer, optimizer_idx: int) -> None:
-        """always called before the optimizer step.
-        Checks that the optimizer is not LBFGS, as this one is not supported by native amp
-        """
-        if isinstance(optimizer, torch.optim.LBFGS):
-            raise MisconfigurationException(
-                f"native PyTorch amp and lbfgs are not compatible (optimizer {optimizer_idx})."
-                " To request, please file a Github issue in PyTorch and tag @mcarilli"
-            )
-
-    def post_optimizer_step(self, optimizer: torch.optim.Optimizer, optimizer_idx: int) -> None:
-        """Updates the GradScaler"""
-        self.scaler.update()
-
     def backward(
         self,
         model: LightningModule,
         closure_loss: torch.Tensor,
-        optimizer: torch.optim.Optimizer,
+        optimizer: Optimizer,
         opt_idx: int,
         should_accumulate: bool,
         *args,
@@ -69,16 +56,39 @@ def backward(
         """
         closure_loss = self.scaler.scale(closure_loss)
 
-        automatic_optimization = model.automatic_optimization
-
         closure_loss = super().backward(model, closure_loss, optimizer, opt_idx, should_accumulate, *args, **kwargs)
 
         # unscale gradient to allow analyze within `on_after_backward`
-        if not should_accumulate and automatic_optimization:
+        if not should_accumulate and model.automatic_optimization:
             self.scaler.unscale_(optimizer)
 
         return closure_loss
 
+    def pre_optimizer_step(
+        self, pl_module: LightningModule, optimizer: Optimizer, optimizer_idx: int, lambda_closure: Callable, **kwargs
+    ) -> bool:
+        """always called before the optimizer step.
+        Checks that the optimizer is not LBFGS, as this one is not supported by native amp
+        """
+        if isinstance(optimizer, LBFGS):
+            raise MisconfigurationException(
+                f"native PyTorch amp and lbfgs are not compatible (optimizer {optimizer_idx})."
+                " To request, please file a Github issue in PyTorch and tag @mcarilli"
+            )
+        lambda_closure()
+
+        if not pl_module.automatic_optimization:
+            self.scaler.unscale_(optimizer)
+
+            pl_module.trainer.call_hook("on_after_backward")
+
+        return False
+
+    def post_optimizer_step(self, optimizer: Optimizer, optimizer_idx: int) -> None:
+        """Updates the GradScaler"""
+        self.scaler.step(optimizer)
+        self.scaler.update()
+
     @contextmanager
     def train_step_context(self) -> Generator[autocast, None, None]:
         """Enable autocast context"""

pytorch_lightning/plugins/precision/precision_plugin.py

@@ -12,9 +12,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 import math
-from typing import Any, Generator, Sequence, Tuple, Union
+from typing import Any, Callable, Generator, Sequence, Tuple, Union
 
 import torch
+from torch.nn import Module
 from torch.optim import Optimizer
 
 from pytorch_lightning.core import LightningModule
@@ -28,7 +29,7 @@ class PrecisionPlugin(Plugin):
     EPSILON = 1e-6
     precision = 32
 
-    def master_params(self, optimizer: torch.optim.Optimizer) -> Generator[torch.Tensor, None, None]:
+    def master_params(self, optimizer: Optimizer) -> Generator[torch.Tensor, None, None]:
         """The master params of the model. Returns the plain model params here.
         Maybe different in other precision plugins.
 
@@ -37,16 +38,16 @@ def master_params(self, optimizer: torch.optim.Optimizer) -> Generator[torch.Ten
             for p in group["params"]:
                 yield p
 
-    def connect(self, model: torch.nn.Module, optimizers: Sequence,
-                lr_schedulers: Sequence) -> Tuple[torch.nn.Module, Sequence, Sequence]:
+    def connect(self, model: Module, optimizers: Sequence,
+                lr_schedulers: Sequence) -> Tuple[Module, Sequence, Sequence]:
         """Connects this plugin to the accelerator and the training process"""
         return model, optimizers, lr_schedulers
 
     def backward(
         self,
         model: LightningModule,
         closure_loss: torch.Tensor,
-        optimizer: torch.optim.Optimizer,
+        optimizer: Optimizer,
         opt_idx: int,
         should_accumulate: bool,
         *args: Any,
@@ -75,6 +76,15 @@ def backward(
 
         return closure_loss
 
+    def pre_optimizer_step(
+        self, pl_module: LightningModule, optimizer: Optimizer, optimizer_idx: int, closure: Callable, **kwargs
+    ) -> bool:
+        """Hook to do something before each optimizer step."""
+        return True
+
+    def post_optimizer_step(self, optimizer: Optimizer, optimizer_idx: int) -> None:
+        """Hook to do something after each optimizer step."""
+
     def clip_gradients(self, optimizer: Optimizer, clip_val: Union[int, float], norm_type: float = float(2.0)) -> None:
         """Clips the gradients to a specific value"""
         # TODO: separate TPU case from here

pytorch_lightning/plugins/training_type/ddp.py

@@ -268,7 +268,7 @@ def barrier(self, *args, **kwargs):
     def broadcast(self, obj: object, src: int = 0) -> object:
         return self.dist.broadcast(obj)
 
-    def pre_backward(self, closure_loss: torch.Tensor, optimizer: Optimizer, opt_idx: int):
+    def pre_backward(self, closure_loss: torch.Tensor, should_accumulate: bool, optimizer: Optimizer, opt_idx: int):
         """Run before precision plugin executes backward"""
         if not self.lightning_module.automatic_optimization and self.model.require_backward_grad_sync:
             prepare_for_backward(self.model, closure_loss)

pytorch_lightning/plugins/training_type/ddp_spawn.py

@@ -239,7 +239,7 @@ def model_to_device(self):
             torch.cuda.set_device(self.root_device)
         self.model.to(self.root_device)
 
-    def pre_backward(self, closure_loss: torch.Tensor, optimizer: Optimizer, opt_idx: int):
+    def pre_backward(self, closure_loss: torch.Tensor, should_accumulate: bool, optimizer: Optimizer, opt_idx: int):
         """Run before precision plugin executes backward"""
         if not self.lightning_module.automatic_optimization and self.model.require_backward_grad_sync:
             prepare_for_backward(self.model, closure_loss)

pytorch_lightning/plugins/training_type/horovod.py

@@ -116,7 +116,7 @@ def broadcast(self, obj: object, src: int = 0) -> object:
         obj = hvd.broadcast_object(obj, src)
         return obj
 
-    def post_backward(self, closure_loss: torch.Tensor, optimizer: Optimizer, opt_idx: int):
+    def post_backward(self, closure_loss: torch.Tensor, should_accumulate: bool, optimizer: Optimizer, opt_idx: int):
         optimizer.synchronize()
 
     def model_to_device(self):

pytorch_lightning/plugins/training_type/training_type_plugin.py

@@ -13,11 +13,11 @@
 # limitations under the License.
 import os
 from abc import ABC, abstractmethod
-from typing import Any, Optional, Sequence, TYPE_CHECKING, Union
+from typing import Any, Optional, TYPE_CHECKING, Union
 
 import torch
+from torch.nn import Module
 from torch.optim import Optimizer
-from pytorch_lightning import _logger as log
 from pytorch_lightning.core.lightning import LightningModule
 from pytorch_lightning.overrides.base import unwrap_lightning_module
 from pytorch_lightning.plugins.base_plugin import Plugin
@@ -69,19 +69,19 @@ def reduce_early_stopping_decision(self, should_stop: bool) -> bool:
         """Reduce the early stopping decision across all possibly spawned processes"""
         return should_stop
 
-    def pre_backward(self, closure_loss: torch.Tensor, optimizer: Optimizer, opt_idx: int):
+    def pre_backward(self, closure_loss: torch.Tensor, should_accumulate: bool, optimizer: Optimizer, opt_idx: int):
         """Run before precision plugin executes backward"""
 
-    def post_backward(self, closure_loss: torch.Tensor, optimizer: Optimizer, opt_idx: int):
+    def post_backward(self, closure_loss: torch.Tensor, should_accumulate: bool, optimizer: Optimizer, opt_idx: int):
         """Run after precision plugin executes backward"""
 
     @property
-    def model(self) -> torch.nn.Module:
+    def model(self) -> Module:
         """Returns the potentially wrapped LightningModule"""
         return self._model
 
     @model.setter
-    def model(self, new_model: torch.nn.Module) -> None:
+    def model(self, new_model: Module) -> None:
         self._model = new_model
 
     @property

tests/trainer/optimization/test_manual_optimization.py

@@ -538,7 +538,7 @@ def training_step(self, batch, batch_idx):
             if self.should_update:
 
                 self.manual_backward(loss, opt)
-                opt.step()
+                opt.step(make_optimizer_step=self.should_have_updated)
 
             return loss.detach() if self.detach else loss
 
@@ -557,7 +557,7 @@ def on_train_batch_end(self, outputs, batch, batch_idx, dataloader_idx):
                         assert torch.sum(self.layer.weight.grad) != 0
             self.count += 1
 
-        def on_train_end(self):
+        def on_train_epoch_end(self, *_, **__):
             assert self.called["training_step"] == 20
             assert self.called["on_train_batch_start"] == 20
             assert self.called["on_train_batch_end"] == 20
@@ -828,7 +828,7 @@ def optimizer_closure():
                     retain_graph = num_backward != backward_idx # noqa E225
                     self.manual_backward(loss_1, opt, retain_graph=retain_graph)
 
-            opt.step(closure=optimizer_closure)
+            opt.step(closure=optimizer_closure, make_optimizer_step=True)
 
         def training_epoch_end(self, outputs) -> None:
             # outputs should be an array with an entry per optimizer