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

CHANGELOG.md

@@ -137,6 +137,9 @@ 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))
+
+
 ### Removed
 
 - Removed deprecated parameter `method` in `pytorch_lightning.utilities.model_helpers.is_overridden` ([#10507](https://github.com/PyTorchLightning/pytorch-lightning/pull/10507))

pytorch_lightning/trainer/connectors/accelerator_connector.py

@@ -116,12 +116,32 @@ def __init__(
 
         self._init_deterministic(deterministic)
 
+        if num_processes:
+            rank_zero_deprecation(
+                f"Setting `Trainer(num_processes={num_processes})` is deprecated in v1.6 and will be removed"
+                " in v1.8. Please use `Trainer(accelerator='cpu', devices={num_processes})` instead."
+            )
         self.num_processes = num_processes
         self.devices = devices
         # `gpus` is the input passed to the Trainer, whereas `gpu_ids` is a list of parsed gpu ids.
+        if gpus:
+            rank_zero_deprecation(
+                f"Setting `Trainer(gpus={gpus})` is deprecated in v1.6 and will be removed"
+                " in v1.8. Please use `Trainer(accelerator='gpu', devices={gpus})` instead."
+            )
         self.gpus = gpus
         self.parallel_device_ids = gpu_ids
+        if tpu_cores:
+            rank_zero_deprecation(
+                f"Setting `Trainer(tpu_cores={tpu_cores})` is deprecated in v1.6 and will be removed"
+                " in v1.8. Please use `Trainer(accelerator='tpu', devices={tpu_cores})` instead."
+            )
         self.tpu_cores = tpu_cores
+        if ipus:
+            rank_zero_deprecation(
+                f"Setting `Trainer(ipus={ipus})` is deprecated in v1.6 and will be removed"
+                " in v1.8. Please use `Trainer(accelerator='ipu', devices={ipus})` instead."
+            )
         self.ipus = ipus
         self.num_nodes = num_nodes
         self.sync_batchnorm = sync_batchnorm

pytorch_lightning/trainer/trainer.py

@@ -136,12 +136,12 @@ def __init__(
         gradient_clip_algorithm: Optional[str] = None,
         process_position: int = 0,
         num_nodes: int = 1,
-        num_processes: int = 1,
+        num_processes: int = 1,  # TODO: Remove in 1.8
         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 1.8
         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 1.8
+        ipus: Optional[int] = None,  # TODO: Remove in 1.8
         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,
@@ -262,6 +262,10 @@ def __init__(
 
             gpus: Number of GPUs to train on (int) or which GPUs to train on (list or str) applied per node
 
+                .. deprecated:: v1.6
+                    ``gpus`` has been deprecated in v1.6 and will be removed in v1.8.
+                    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.
 
@@ -349,6 +353,10 @@ def __init__(
 
             num_processes: Number of processes for distributed training with ``accelerator="cpu"``.
 
+                .. deprecated:: v1.6
+                    ``num_processes`` has been deprecated in v1.6 and will be removed in v1.8.
+                    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.
 
@@ -383,8 +391,16 @@ def __init__(
 
             tpu_cores: How many TPU cores to train on (1 or 8) / Single TPU to train on [1]
 
+                .. deprecated:: v1.6
+                    ``tpu_cores`` has been deprecated in v1.6 and will be removed in v1.8.
+                    Please use ``accelerator='tpu'`` and ``devices=x`` instead.
+
             ipus: How many IPUs to train on.
 
+                .. deprecated:: v1.6
+                    ``ipus`` has been deprecated in v1.6 and will be removed in v1.8.
+                    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.
 

tests/deprecated_api/test_remove_1-8.py

@@ -21,6 +21,7 @@
 from pytorch_lightning.utilities.enums import DeviceType, DistributedType
 from pytorch_lightning.utilities.imports import _TORCHTEXT_LEGACY
 from tests.helpers.boring_model import BoringModel
+from tests.helpers.runif import RunIf
 from tests.helpers.torchtext_utils import get_dummy_torchtext_data_iterator
 
 
@@ -106,3 +107,26 @@ def on_hpc_load(self):
         match=r"Method `LightningModule.on_hpc_load` is deprecated in v1.6 and will be removed in v1.8."
     ):
         trainer.fit(load_model)
+
+
+def test_v1_8_0_deprecated_num_processes(tmpdir):
+    with pytest.deprecated_call(match=r"is deprecated in v1.6 and will be removed in v1.8."):
+        _ = Trainer(default_root_dir=tmpdir, num_processes=2)
+
+
+@RunIf(gpu=True)
+def test_v1_8_0_deprecated_gpus(tmpdir):
+    with pytest.deprecated_call(match=r"is deprecated in v1.6 and will be removed in v1.8."):
+        _ = Trainer(default_root_dir=tmpdir, gpus=2)
+
+
+@RunIf(tpu=True)
+def test_v1_8_0_deprecated_tpu_cores(tmpdir):
+    with pytest.deprecated_call(match=r"is deprecated in v1.6 and will be removed in v1.8."):
+        _ = Trainer(default_root_dir=tmpdir, tpu_cores=1)
+
+
+@RunIf(ipu=True)
+def test_v1_8_0_deprecated_ipus(tmpdir):
+    with pytest.deprecated_call(match=r"is deprecated in v1.6 and will be removed in v1.8."):
+        _ = Trainer(default_root_dir=tmpdir, ipus=2)