lightning/tests/trainer/dynamic_args/test_multiple_optimizers.py

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from pytorch_lightning import Trainer
from tests.base.boring_model import BoringModel
import torch
def test_multiple_optimizers(tmpdir):
"""
Tests that only training_step can be used
"""
class TestModel(BoringModel):
def on_train_epoch_start(self) -> None:
self.opt_0_seen = False
self.opt_1_seen = False
def training_step(self, batch, batch_idx, optimizer_idx):
if optimizer_idx == 0:
self.opt_0_seen = True
elif optimizer_idx == 1:
self.opt_1_seen = True
else:
raise Exception('should only have two optimizers')
self.training_step_called = True
loss = self.step(batch[0])
return loss
def training_epoch_end(self, outputs) -> None:
# outputs should be an array with an entry per optimizer
assert len(outputs) == 2
def configure_optimizers(self):
optimizer = torch.optim.SGD(self.layer.parameters(), lr=0.1)
optimizer_2 = torch.optim.SGD(self.layer.parameters(), lr=0.1)
return optimizer, optimizer_2
model = TestModel()
model.val_dataloader = None
trainer = Trainer(
default_root_dir=tmpdir,
limit_train_batches=2,
limit_val_batches=2,
max_epochs=1,
row_log_interval=1,
weights_summary=None,
)
trainer.fit(model)
assert model.opt_0_seen
assert model.opt_1_seen