Deprecate num_processes,gpus, tpu_cores, and ipus from the Trainer constructor

CHANGELOG.md

@@ -370,6 +370,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Deprecated `ModelIO.on_hpc_{save/load}` in favor of `CheckpointHooks.on_{save/load}_checkpoint` ([#10911](https://github.com/PyTorchLightning/pytorch-lightning/pull/10911))
 
 
+- Deprecated `num_processes`, `gpus`, `tpu_cores,` and `ipus` from the `Trainer` constructor in favor of using the `accelerator` and `devices` arguments ([#11040](https://github.com/PyTorchLightning/pytorch-lightning/pull/11040))
+
+
 - Deprecated `Trainer.run_stage` in favor of `Trainer.{fit,validate,test,predict}` ([#11000](https://github.com/PyTorchLightning/pytorch-lightning/pull/11000))
 
 

pytorch_lightning/trainer/connectors/accelerator_connector.py

@@ -395,7 +395,7 @@ def _check_device_config_and_set_final_flags(
         self._devices_flag = devices
 
         # TODO: Delete this method when num_processes, gpus, ipus and tpu_cores gets removed
-        self._map_deprecated_devices_specfic_info_to_accelerator_and_device_flag(
+        self._map_deprecated_devices_specific_info_to_accelerator_and_device_flag(
             devices, num_processes, gpus, ipus, tpu_cores
         )
 
@@ -409,15 +409,36 @@ def _check_device_config_and_set_final_flags(
                 " `accelerator=('auto'|'tpu'|'gpu'|'ipu'|'cpu')` for the devices mapping"
             )
 
-    def _map_deprecated_devices_specfic_info_to_accelerator_and_device_flag(
+    def _map_deprecated_devices_specific_info_to_accelerator_and_device_flag(
         self,
         devices: Optional[Union[List[int], str, int]],
         num_processes: Optional[int],
         gpus: Optional[Union[List[int], str, int]],
         ipus: Optional[int],
         tpu_cores: Optional[Union[List[int], str, int]],
     ) -> None:
-        """Sets the `devices_flag` and `accelerator_flag` based on num_processes, gpus, ipus, tpu_cores."""
+        """Emit deprecation warnings for num_processes, gpus, ipus, tpu_cores and set the `devices_flag` and
+        `accelerator_flag`."""
+        if num_processes:
+            rank_zero_deprecation(
+                f"Setting `Trainer(num_processes={num_processes})` is deprecated in v1.6 and will be removed"
+                f" in v2.0. Please use `Trainer(accelerator='cpu', devices={num_processes})` instead."
+            )
+        if gpus:
+            rank_zero_deprecation(
+                f"Setting `Trainer(gpus={gpus})` is deprecated in v1.6 and will be removed"
+                f" in v2.0. Please use `Trainer(accelerator='gpu', devices={gpus})` instead."
+            )
+        if tpu_cores:
+            rank_zero_deprecation(
+                f"Setting `Trainer(tpu_cores={tpu_cores})` is deprecated in v1.6 and will be removed"
+                f" in v2.0. Please use `Trainer(accelerator='tpu', devices={tpu_cores})` instead."
+            )
+        if ipus:
+            rank_zero_deprecation(
+                f"Setting `Trainer(ipus={ipus})` is deprecated in v1.6 and will be removed"
+                f" in v2.0. Please use `Trainer(accelerator='ipu', devices={ipus})` instead."
+            )
         self._gpus: Optional[Union[List[int], str, int]] = gpus
         self._tpu_cores: Optional[Union[List[int], str, int]] = tpu_cores
         deprecated_devices_specific_flag = num_processes or gpus or ipus or tpu_cores

pytorch_lightning/trainer/trainer.py

@@ -137,12 +137,12 @@ def __init__(
         gradient_clip_algorithm: Optional[str] = None,
         process_position: int = 0,
         num_nodes: int = 1,
-        num_processes: Optional[int] = None,
+        num_processes: Optional[int] = None,  # TODO: Remove in 2.0
         devices: Optional[Union[List[int], str, int]] = None,
-        gpus: Optional[Union[List[int], str, int]] = None,
+        gpus: Optional[Union[List[int], str, int]] = None,  # TODO: Remove in 2.0
         auto_select_gpus: bool = False,
-        tpu_cores: Optional[Union[List[int], str, int]] = None,
-        ipus: Optional[int] = None,
+        tpu_cores: Optional[Union[List[int], str, int]] = None,  # TODO: Remove in 2.0
+        ipus: Optional[int] = None,  # TODO: Remove in 2.0
         log_gpu_memory: Optional[str] = None,  # TODO: Remove in 1.7
         progress_bar_refresh_rate: Optional[int] = None,  # TODO: remove in v1.7
         enable_progress_bar: bool = True,
@@ -278,6 +278,10 @@ def __init__(
             gpus: Number of GPUs to train on (int) or which GPUs to train on (list or str) applied per node
                 Default: ``None``.
 
+                .. deprecated:: v1.6
+                    ``gpus`` has been deprecated in v1.6 and will be removed in v2.0.
+                    Please use ``accelerator='gpu'`` and ``devices=x`` instead.
+
             gradient_clip_val: The value at which to clip gradients. Passing ``gradient_clip_val=None`` disables
                 gradient clipping. If using Automatic Mixed Precision (AMP), the gradients will be unscaled before.
                 Default: ``None``.
@@ -378,6 +382,10 @@ def __init__(
             num_processes: Number of processes for distributed training with ``accelerator="cpu"``.
                 Default: ``1``.
 
+                .. deprecated:: v1.6
+                    ``num_processes`` has been deprecated in v1.6 and will be removed in v2.0.
+                    Please use ``accelerator='cpu'`` and ``devices=x`` instead.
+
             num_sanity_val_steps: Sanity check runs n validation batches before starting the training routine.
                 Set it to `-1` to run all batches in all validation dataloaders.
                 Default: ``2``.
@@ -418,9 +426,17 @@ def __init__(
             tpu_cores: How many TPU cores to train on (1 or 8) / Single TPU to train on (1)
                 Default: ``None``.
 
+                .. deprecated:: v1.6
+                    ``tpu_cores`` has been deprecated in v1.6 and will be removed in v2.0.
+                    Please use ``accelerator='tpu'`` and ``devices=x`` instead.
+
             ipus: How many IPUs to train on.
                 Default: ``None``.
 
+                .. deprecated:: v1.6
+                    ``ipus`` has been deprecated in v1.6 and will be removed in v2.0.
+                    Please use ``accelerator='ipu'`` and ``devices=x`` instead.
+
             track_grad_norm: -1 no tracking. Otherwise tracks that p-norm. May be set to 'inf' infinity-norm. If using
                 Automatic Mixed Precision (AMP), the gradients will be unscaled before logging them.
                 Default: ``-1``.

tests/deprecated_api/test_remove_2-0.py

@@ -11,12 +11,39 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-"""Test deprecated functionality which will be removed in v2.0."""
+"""Test deprecated functionality which will be removed in v2.0.0."""
+from unittest import mock
+
 import pytest
 
 from pytorch_lightning import Trainer
 from tests.callbacks.test_callbacks import OldStatefulCallback
 from tests.helpers import BoringModel
+from tests.helpers.runif import RunIf
+
+
+def test_v2_0_0_deprecated_num_processes(tmpdir):
+    with pytest.deprecated_call(match=r"is deprecated in v1.6 and will be removed in v2.0."):
+        _ = Trainer(default_root_dir=tmpdir, num_processes=2)
+
+
+@mock.patch("torch.cuda.is_available", return_value=True)
+@mock.patch("torch.cuda.device_count", return_value=2)
+def test_v2_0_0_deprecated_gpus(mock_is_available, mock_device_count, tmpdir):
+    with pytest.deprecated_call(match=r"is deprecated in v1.6 and will be removed in v2.0."):
+        _ = Trainer(default_root_dir=tmpdir, gpus=2)
+
+
+@RunIf(tpu=True)
+def test_v2_0_0_deprecated_tpu_cores(tmpdir):
+    with pytest.deprecated_call(match=r"is deprecated in v1.6 and will be removed in v2.0."):
+        _ = Trainer(default_root_dir=tmpdir, tpu_cores=1)
+
+
+@RunIf(ipu=True)
+def test_v2_0_0_deprecated_ipus(tmpdir):
+    with pytest.deprecated_call(match=r"is deprecated in v1.6 and will be removed in v2.0."):
+        _ = Trainer(default_root_dir=tmpdir, ipus=2)
 
 
 def test_v2_0_resume_from_checkpoint_trainer_constructor(tmpdir):