Set precision=16 when use_amp is passed as True (Lightning-AI#1145)

* Set precision=16 when use_amp is passed as True

* Update CHANGELOG.md

* add use_amp to deprecated API

* Update trainer.py

* Update trainer.py

* move the use_amp attribute to deprecated API

* move use_amp deprecation back to Trainer's __init__

* drop unsed

* drop deprecated

* reorder imports

* typing

Co-authored-by: Jirka Borovec <Borda@users.noreply.github.com>
Co-authored-by: William Falcon <waf2107@columbia.edu>
Co-authored-by: J. Borovec <jirka.borovec@seznam.cz>

CHANGELOG.md

@@ -81,6 +81,8 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Fixed checkpointing interval ([#1272](https://github.com/PyTorchLightning/pytorch-lightning/pull/1272)) 
 - Fixed validation and training loops run the partial dataset ([#1192](https://github.com/PyTorchLightning/pytorch-lightning/pull/1192))
 - Fixed running `on_validation_end` only on main process in DDP ([#1125](https://github.com/PyTorchLightning/pytorch-lightning/pull/1125))
+- Fixes `use_amp` issue ([#1145](https://github.com/PyTorchLightning/pytorch-lightning/pull/1145))
+- Fixes using deprecated `use_amp` attribute ([#1145](https://github.com/PyTorchLightning/pytorch-lightning/pull/1145))
 
 ## [0.7.1] - 2020-03-07
 

pl_examples/basic_examples/gpu_template.py

@@ -32,7 +32,7 @@ def main(hparams):
         max_epochs=hparams.epochs,
         gpus=hparams.gpus,
         distributed_backend=hparams.distributed_backend,
-        use_amp=hparams.use_16bit
+        precision=16 if hparams.use_16bit else 32,
     )
 
     # ------------------------

pl_examples/domain_templates/imagenet.py

@@ -226,7 +226,7 @@ def main(hparams):
         gpus=hparams.gpus,
         max_epochs=hparams.epochs,
         distributed_backend=hparams.distributed_backend,
-        use_amp=hparams.use_16bit
+        precision=16 if hparams.use_16bit else 32,
     )
     if hparams.evaluate:
         trainer.run_evaluation()

pytorch_lightning/trainer/auto_mix_precision.py

@@ -14,19 +14,21 @@ class TrainerAMPMixin(ABC):
 
     # this is just a summary on variables used in this abstract class,
     #  the proper values/initialisation should be done in child class
-    use_amp: bool
+    precision: int
 
     def init_amp(self, use_amp):
-        self.use_amp = use_amp and APEX_AVAILABLE
-        if self.use_amp:
-            log.info('Using 16bit precision.')
-
         if use_amp and not APEX_AVAILABLE:  # pragma: no-cover
-            msg = """
+            raise ModuleNotFoundError("""
             You set `use_amp=True` but do not have apex installed.
             Install apex first using this guide and rerun with use_amp=True:
             https://github.com/NVIDIA/apex#linux
 
             this run will NOT use 16 bit precision
-            """
-            raise ModuleNotFoundError(msg)
+            """)
+
+        if self.use_amp:
+            log.info('Using 16bit precision.')
+
+    @property
+    def use_amp(self) -> bool:
+        return self.precision == 16 and APEX_AVAILABLE

pytorch_lightning/trainer/distrib_data_parallel.py

@@ -141,7 +141,6 @@ class TrainerDDPMixin(ABC):
     logger: Union[LightningLoggerBase, bool]
     data_parallel_device_ids: ...
     distributed_backend: str
-    use_amp: bool
     amp_level: str
     use_tpu: bool
     default_save_path: str
@@ -151,6 +150,11 @@ class TrainerDDPMixin(ABC):
     def num_gpus(self) -> int:
         """Warning: this is just empty shell for code implemented in other class."""
 
+    @property
+    @abstractmethod
+    def use_amp(self) -> bool:
+        """Warning: this is just empty shell for code implemented in other class."""
+
     @abstractmethod
     def copy_trainer_model_properties(self, *args):
         """Warning: this is just empty shell for code implemented in other class."""

pytorch_lightning/trainer/distrib_parts.py

@@ -372,7 +372,6 @@ class TrainerDPMixin(ABC):
     use_dp: bool
     use_ddp2: bool
     use_ddp: bool
-    use_amp: bool
     testing: bool
     single_gpu: bool
     root_gpu: ...
@@ -385,6 +384,11 @@ class TrainerDPMixin(ABC):
     use_tpu: bool
     data_parallel_device_ids: ...
 
+    @property
+    @abstractmethod
+    def use_amp(self) -> bool:
+        """Warning: this is just empty shell for code implemented in other class."""
+
     @abstractmethod
     def run_pretrain_routine(self, *args):
         """Warning: this is just empty shell for code implemented in other class."""

pytorch_lightning/trainer/trainer.py

@@ -21,8 +21,7 @@
 from pytorch_lightning.trainer.callback_config import TrainerCallbackConfigMixin
 from pytorch_lightning.trainer.callback_hook import TrainerCallbackHookMixin
 from pytorch_lightning.trainer.data_loading import TrainerDataLoadingMixin
-from pytorch_lightning.trainer.deprecated_api import (TrainerDeprecatedAPITillVer0_8,
-                                                      TrainerDeprecatedAPITillVer0_9)
+from pytorch_lightning.trainer.deprecated_api import TrainerDeprecatedAPITillVer0_8, TrainerDeprecatedAPITillVer0_9
 from pytorch_lightning.trainer.distrib_data_parallel import TrainerDDPMixin
 from pytorch_lightning.trainer.distrib_parts import TrainerDPMixin, parse_gpu_ids, determine_root_gpu_device
 from pytorch_lightning.trainer.evaluation_loop import TrainerEvaluationLoopMixin
@@ -55,13 +54,13 @@
 class Trainer(
     TrainerIOMixin,
     TrainerOptimizersMixin,
+    TrainerAMPMixin,
     TrainerDPMixin,
     TrainerDDPMixin,
     TrainerLoggingMixin,
     TrainerModelHooksMixin,
     TrainerTrainingTricksMixin,
     TrainerDataLoadingMixin,
-    TrainerAMPMixin,
     TrainerEvaluationLoopMixin,
     TrainerTrainLoopMixin,
     TrainerCallbackConfigMixin,
@@ -88,7 +87,6 @@ def __init__(
             gpus: Optional[Union[List[int], str, int]] = None,
             num_tpu_cores: Optional[int] = None,
             log_gpu_memory: Optional[str] = None,
-            show_progress_bar=None,  # backward compatible, todo: remove in v0.9.0
             progress_bar_refresh_rate: int = 1,
             overfit_pct: float = 0.0,
             track_grad_norm: int = -1,
@@ -122,7 +120,8 @@ def __init__(
             nb_gpu_nodes=None,  # backward compatible, todo: remove in v0.8.0
             max_nb_epochs=None,  # backward compatible, todo: remove in v0.8.0
             min_nb_epochs=None,  # backward compatible, todo: remove in v0.8.0
-            use_amp=False,  # backward compatible, todo: remove in v0.9.0
+            use_amp=None,  # backward compatible, todo: remove in v0.9.0
+            show_progress_bar=None,  # backward compatible, todo: remove in v0.9.0
             nb_sanity_val_steps=None,  # backward compatible, todo: remove in v0.8.0
             **kwargs
     ):
@@ -446,6 +445,12 @@ def __init__(
         self.amp_level = amp_level
         self.precision = precision
 
+        # Backward compatibility, TODO: remove in v0.9.0
+        if use_amp is not None:
+            warnings.warn("`use_amp` has been replaced by `precision` since v0.7.0"
+                          " and this argument will be removed in v0.9.0", DeprecationWarning)
+            self.precision = 16 if use_amp else 32
+
         assert self.precision in (16, 32), 'only 32 or 16 bit precision supported'
 
         if self.precision == 16 and self.num_tpu_cores is None:

pytorch_lightning/trainer/training_loop.py

@@ -200,7 +200,6 @@ class TrainerTrainLoopMixin(ABC):
     optimizers: ...
     optimizer_frequencies: ...
     accumulate_grad_batches: int
-    use_amp: bool
     track_grad_norm: ...
     model: LightningModule
     interrupted: bool