[pipeline] set optimizer to optional in execute_pipeline (#4630)

* set optimizer to optional in execute_pipeline

* arrange device and mixed precision in booster init

* fix execute_pipeline in booster.py

colossalai/booster/booster.py

@@ -49,7 +49,9 @@ class Booster:
         ```
 
     Args:
-        device (str or torch.device): The device to run the training. Default: 'cuda'.
+        device (str or torch.device): The device to run the training. Default: None.
+                                      If plugin is not used or plugin doesn't control the device,
+                                      this argument will be set as training device ('cuda' will be used if argument is None).
         mixed_precision (str or MixedPrecision): The mixed precision to run the training. Default: None.
                                 If the argument is a string, it can be 'fp16', 'fp16_apex', 'bf16', or 'fp8'.
                                 'fp16' would use PyTorch AMP while `fp16_apex` would use Nvidia Apex.
@@ -57,7 +59,7 @@ class Booster:
     """
 
     def __init__(self,
-                 device: str = 'cuda',
+                 device: Optional[str] = None,
                  mixed_precision: Union[MixedPrecision, str] = None,
                  plugin: Optional[Plugin] = None) -> None:
         if plugin is not None:
@@ -68,13 +70,16 @@ class Booster:
         # set accelerator
         if self.plugin and self.plugin.control_device():
             self.accelerator = None
-            warnings.warn('The plugin will control the accelerator, so the device argument will be ignored.')
+            if device is not None:
+                warnings.warn('The plugin will control the accelerator, so the device argument will be ignored.')
         else:
+            device = device or 'cuda'
             self.accelerator = Accelerator(device)
 
         # set precision
         if self.plugin and self.plugin.control_precision():
-            warnings.warn('The plugin will control the precision, so the mixed_precision argument will be ignored.')
+            if mixed_precision is not None:
+                warnings.warn('The plugin will control the precision, so the mixed_precision argument will be ignored.')
             self.mixed_precision = None
         elif mixed_precision is None:
             self.mixed_precision = None
@@ -146,7 +151,7 @@ class Booster:
                          data_iter: Iterator,
                          model: nn.Module,
                          criterion: Callable[[Any, Any], torch.Tensor],
-                         optimizer: Optimizer,
+                         optimizer: Optional[Optimizer] = None,
                          return_loss: bool = True,
                          return_outputs: bool = False) -> dict:
         # run pipeline forward backward pass

colossalai/booster/plugin/hybrid_parallel_plugin.py

@@ -443,15 +443,15 @@ class HybridParallelPlugin(PipelinePluginBase):
                          data_iter: Iterator,
                          model: HybridParallelModule,
                          criterion: Callable[[Any, Any], torch.Tensor],
-                         optimizer: Union[HybridParallelNaiveOptimizer, HybridParallelAMPOptimizer,
-                                          HybridParallelZeroOptimizer],
+                         optimizer: Optional[Union[HybridParallelNaiveOptimizer, HybridParallelAMPOptimizer,
+                                                   HybridParallelZeroOptimizer]] = None,
                          return_loss: bool = True,
                          return_outputs: bool = False) -> dict:
         assert self.enable_pipeline_parallelism, 'pipeline parallelism is not enabled'
         # return loss or outputs if needed
         ctx = optimizer.no_sync() if isinstance(optimizer, HybridParallelZeroOptimizer) else model.no_sync()
         with ctx:
-            outputs = self.schedule.forward_backward_step(model, optimizer, data_iter, criterion, return_loss,
+            outputs = self.schedule.forward_backward_step(model, data_iter, criterion, optimizer, return_loss,
                                                           return_outputs)
         model.sync_shared_params()
         if isinstance(optimizer, HybridParallelZeroOptimizer):

colossalai/booster/plugin/pp_plugin_base.py

 from abc import abstractmethod
-from typing import Any, Callable, Iterator
+from typing import Any, Callable, Iterator, Optional
 
 import torch
 
@@ -15,7 +15,7 @@ class PipelinePluginBase(Plugin):
                          data_iter: Iterator,
                          model: ModelWrapper,
                          criterion: Callable[[Any, Any], torch.Tensor],
-                         optimizer: OptimizerWrapper,
+                         optimizer: Optional[OptimizerWrapper] = None,
                          return_loss: bool = True,
                          return_outputs: bool = False) -> dict:
         pass

colossalai/pipeline/schedule/base.py

-from typing import Any, Callable, Iterable
+from typing import Any, Callable, Iterable, Optional
 
 from torch import Tensor
 from torch.nn import Module
@@ -14,18 +14,18 @@ class PipelineSchedule:
 
     def forward_backward_step(self,
                               model: Module,
-                              optimizer: OptimizerWrapper,
                               data_iter: Iterable,
                               criterion: Callable[[Any, Any], Tensor],
+                              optimizer: Optional[OptimizerWrapper] = None,
                               return_loss: bool = False,
                               return_outputs: bool = False) -> dict:
         """Forward and backward step for pipeline training.
 
         Args:
             model (Module): Model to be trained.
-            optimizer (OptimizerWrapper): Optimizer to be used.
             data_iter (Iterable): Data iterator.
             criterion (Callable[[Any, Any], Tensor]): Criterion to be used. It should take two arguments: model outputs and inputs, and returns loss tensor.
+            optimizer (OptimizerWrapper, optional): Optimizer to be used. Can be None when only forward is executed. Defaults to None.
             return_loss (bool, optional): Whether to return loss. Defaults to False. Whether to return loss.
             return_outputs (bool, optional): Whether to return model outputs. Defaults to False. Whether to return model outputs.
 

colossalai/pipeline/schedule/interleaved_pp.py

@@ -237,18 +237,18 @@ class InterleavedSchedule(PipelineSchedule):
 
     def forward_backward_step(self,
                               model_chunk: Module,
-                              optimizer: OptimizerWrapper,
                               data_iter: Iterable,
                               criterion: Callable[..., Any],
+                              optimizer: Optional[OptimizerWrapper] = None,
                               return_loss: bool = False,
                               return_outputs: bool = False) -> dict:
         """Runs interleaved 1F1B schedule, with communication between pipeline stages.
 
         Args:
             model_chunk (List[Module]): Model Chunk to be trained.
-            optimizer (OptimizerWrapper): Optimizer to be used.
             data_iter (Iterable): Data iterator.
             criterion (Callable[[Any, Any], Tensor]): Criterion to be used. It should take two arguments: model outputs and inputs, and returns loss tensor.
+            optimizer (OptimizerWrapper, optional): Optimizer to be used. Can be None when only forward is executed. Defaults to None.
             return_loss (bool, optional): Whether to return loss. Defaults to False. Whether to return loss.
             return_outputs (bool, optional): Whether to return model outputs. Defaults to False. Whether to return model outputs.
 
@@ -256,6 +256,8 @@ class InterleavedSchedule(PipelineSchedule):
             dict: A dict with keys: 'loss' and 'outputs'.
         """
         forward_only = not torch.is_grad_enabled()
+        if optimizer is None:
+            assert forward_only, "Optimizer should be passed when doing backward."
 
         self.load_batch(data_iter)
         num_model_chunks = len(model_chunk)

colossalai/pipeline/schedule/one_f_one_b.py

@@ -210,18 +210,18 @@ class OneForwardOneBackwardSchedule(PipelineSchedule):
 
     def forward_backward_step(self,
                               model: Module,
-                              optimizer: OptimizerWrapper,
                               data_iter: Iterable,
                               criterion: Callable[..., Any],
+                              optimizer: Optional[OptimizerWrapper] = None,
                               return_loss: bool = False,
                               return_outputs: bool = False) -> dict:
         """Runs non-interleaved 1F1B schedule, with communication between pipeline stages.
 
         Args:
             model (Module): Model to be trained.
-            optimizer (OptimizerWrapper): Optimizer to be used.
             data_iter (Iterable): Data iterator.
             criterion (Callable[[Any, Any], Tensor]): Criterion to be used. It should take two arguments: model outputs and inputs, and returns loss tensor.
+            optimizer (OptimizerWrapper, optional): Optimizer to be used. Can be None when only forward is executed. Defaults to None.
             return_loss (bool, optional): Whether to return loss. Defaults to False. Whether to return loss.
             return_outputs (bool, optional): Whether to return model outputs. Defaults to False. Whether to return model outputs.
 
@@ -229,6 +229,8 @@ class OneForwardOneBackwardSchedule(PipelineSchedule):
             dict: A dict with keys: 'loss' and 'outputs'.
         """
         forward_only = not torch.is_grad_enabled()
+        if optimizer is None:
+            assert forward_only, "Optimizer should be passed when doing backward."
 
         self.load_batch(data_iter)
 

examples/language/bert/finetune.py

@@ -46,7 +46,6 @@ def move_to_cuda(batch):
 @torch.no_grad()
 def evaluate_model(
     model: nn.Module,
-    optimizer,
     criterion,
     test_dataloader: Union[DataLoader, List[DataLoader]],
     num_labels: int,
@@ -71,12 +70,7 @@ def evaluate_model(
                 current_rank = dist.get_rank()
                 #TODO pass dataloader to execute_pipeline directly
                 batch = iter([batch])
-                outputs = booster.execute_pipeline(batch,
-                                                   model,
-                                                   criterion,
-                                                   optimizer,
-                                                   return_loss=True,
-                                                   return_outputs=True)
+                outputs = booster.execute_pipeline(batch, model, criterion, return_loss=True, return_outputs=True)
 
                 if booster.plugin.stage_manager.is_last_stage():
                     val_loss = outputs["loss"]
@@ -304,7 +298,7 @@ def main():
     for epoch in range(NUM_EPOCHS):
         train_epoch(epoch, model, optimizer, _criterion, lr_scheduler, train_dataloader, booster, coordinator)
 
-    results = evaluate_model(model, optimizer, _criterion, test_dataloader, data_builder.num_labels, args.task,
+    results = evaluate_model(model, _criterion, test_dataloader, data_builder.num_labels, args.task,
                              data_builder.eval_splits, booster, coordinator)
 
     if coordinator.is_master():

tests/test_pipeline/test_schedule/test_interleaved.py

@@ -110,9 +110,9 @@ def examine_pp(num_micro_batches):
     torch_loss.backward()
 
     pp_ret = schedule.forward_backward_step(sharded_model,
-                                            pp_optimizer,
                                             iter(input_list),
                                             criterion,
+                                            pp_optimizer,
                                             return_loss=True,
                                             return_outputs=True)
 

tests/test_pipeline/test_schedule/test_oneF_oneB.py

@@ -90,9 +90,9 @@ def examine_pp():
     torch_loss.backward()
 
     pp_ret = schedule.forward_backward_step(sharded_model,
-                                            pp_optimizer,
                                             iter(input_list),
                                             criterion,
+                                            pp_optimizer,
                                             return_loss=True,
                                             return_outputs=True)