lightning/tests/plugins/test_ddp_spawn_plugin.py

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# Copyright The PyTorch Lightning team.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# 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.
import torch
from pytorch_lightning import Trainer
from pytorch_lightning.plugins import DDPSpawnPlugin
from tests.helpers.boring_model import BoringModel
from tests.helpers.runif import RunIf
class BoringModelDDPCPU(BoringModel):
def on_train_start(self) -> None:
# make sure that the model is on CPU when training
assert self.device == torch.device("cpu")
@RunIf(skip_windows=True)
def test_ddp_cpu():
"""Tests if device is set correctely when training for DDPSpawnPlugin."""
trainer = Trainer(num_processes=2, fast_dev_run=True)
# assert training type plugin attributes for device setting
assert isinstance(trainer.training_type_plugin, DDPSpawnPlugin)
assert not trainer.training_type_plugin.on_gpu
assert not trainer.training_type_plugin.on_tpu
assert trainer.training_type_plugin.root_device == torch.device("cpu")
model = BoringModelDDPCPU()
trainer.fit(model)