lightning/tests/tests_fabric/strategies/test_fsdp.py

134 lines
4.9 KiB
Python

# Copyright The Lightning AI 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.
from unittest import mock
from unittest.mock import ANY, MagicMock, Mock
import pytest
import torch
import torch.nn as nn
from tests_fabric.helpers.runif import RunIf
from torch.optim import Adam
from lightning.fabric.strategies import FSDPStrategy
from lightning.fabric.strategies.fsdp import _FSDPBackwardSyncControl
from lightning.fabric.utilities.imports import _TORCH_GREATER_EQUAL_1_12
if _TORCH_GREATER_EQUAL_1_12:
from torch.distributed.fsdp.fully_sharded_data_parallel import CPUOffload, FullyShardedDataParallel, MixedPrecision
@mock.patch("lightning.fabric.strategies.fsdp._TORCH_GREATER_EQUAL_1_12", False)
def test_fsdp_support(*_):
with pytest.raises(NotImplementedError, match="`FSDPStrategy` is supported from PyTorch v1.12.0"):
FSDPStrategy()
@RunIf(min_torch="1.12")
def test_fsdp_custom_mixed_precision():
"""Test that passing a custom mixed precision config works."""
config = MixedPrecision()
strategy = FSDPStrategy(mixed_precision=config)
assert strategy.mixed_precision_config == config
@RunIf(min_torch="1.12")
def test_fsdp_cpu_offload():
"""Test the different ways cpu offloading can be enabled."""
# bool
strategy = FSDPStrategy(cpu_offload=True)
assert strategy.cpu_offload == CPUOffload(offload_params=True)
# dataclass
config = CPUOffload()
strategy = FSDPStrategy(cpu_offload=config)
assert strategy.cpu_offload == config
@RunIf(min_torch="1.12")
def test_fsdp_setup_optimizer_validation():
"""Test that `setup_optimizer()` validates the param groups and reference to FSDP parameters."""
module = nn.Linear(2, 2)
strategy = FSDPStrategy(parallel_devices=[torch.device("cpu")])
bad_optimizer = Adam([{"params": [module.weight]}, {"params": [module.bias], "lr": 1e-3}])
with pytest.raises(ValueError, match="does not support multiple param groups"):
strategy.setup_optimizer(bad_optimizer)
bad_optimizer = Adam(module.parameters())
with pytest.raises(ValueError, match="The optimizer does not seem to reference any FSDP parameter"):
strategy.setup_optimizer(bad_optimizer)
@RunIf(min_torch="1.12")
def test_fsdp_no_backward_sync():
"""Test that the backward sync control calls `.no_sync()`, and only on a module wrapped in
FullyShardedDataParallel."""
strategy = FSDPStrategy()
assert isinstance(strategy._backward_sync_control, _FSDPBackwardSyncControl)
with pytest.raises(
TypeError, match="is only possible if the module passed to .* is wrapped in `FullyShardedDataParallel`"
):
with strategy._backward_sync_control.no_backward_sync(Mock()):
pass
module = MagicMock(spec=FullyShardedDataParallel)
with strategy._backward_sync_control.no_backward_sync(module):
pass
module.no_sync.assert_called_once()
@RunIf(min_torch="1.12")
@mock.patch("lightning.fabric.strategies.fsdp._TORCH_GREATER_EQUAL_1_13", False)
def test_fsdp_activation_checkpointing_support():
"""Test that we error out if activation checkpointing requires a newer PyTorch version."""
with pytest.raises(ValueError, match="Activation checkpointing requires torch >= 1.13.0"):
FSDPStrategy(activation_checkpointing=Mock())
@RunIf(min_torch="1.13")
def test_fsdp_activation_checkpointing():
"""Test that the FSDP strategy can apply activation checkpointing to the given layers."""
class Block1(nn.Linear):
pass
class Block2(nn.Linear):
pass
class Model(nn.Module):
def __init__(self):
super().__init__()
self.layer0 = nn.Sequential(Block1(4, 4), Block1(5, 5))
self.layer1 = Block2(2, 2)
self.layer2 = nn.Linear(3, 3)
strategy = FSDPStrategy(activation_checkpointing=Block1)
assert strategy._activation_checkpointing == [Block1]
strategy = FSDPStrategy(activation_checkpointing=[Block1, Block2])
assert strategy._activation_checkpointing == [Block1, Block2]
strategy._parallel_devices = [torch.device("cuda", 0)]
with mock.patch(
"torch.distributed.fsdp.fully_sharded_data_parallel.FullyShardedDataParallel"
) as fsdp_mock, mock.patch(
"torch.distributed.algorithms._checkpoint.checkpoint_wrapper.apply_activation_checkpointing"
) as ckpt_mock:
strategy.setup_module(Model())
ckpt_mock.assert_called_with(fsdp_mock(), checkpoint_wrapper_fn=ANY, check_fn=ANY)