lightning/tests/tests_fabric/strategies/test_xla.py

151 lines
5.8 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.
import os
from functools import partial
from unittest import mock
from unittest.mock import MagicMock, Mock
import pytest
import torch
from tests_fabric.helpers.dataloaders import CustomNotImplementedErrorDataloader
from tests_fabric.helpers.models import RandomDataset, RandomIterableDataset
from tests_fabric.helpers.runif import RunIf
from torch.utils.data import DataLoader
from lightning.fabric.accelerators import TPUAccelerator
from lightning.fabric.strategies import XLAStrategy
from lightning.fabric.strategies.launchers.xla import _XLALauncher
from lightning.fabric.utilities.distributed import ReduceOp
def wrap_launch_function(fn, strategy, *args, **kwargs):
# the launcher does not manage this automatically. explanation available in:
# https://github.com/Lightning-AI/lightning/pull/14926#discussion_r982976718
strategy.setup_environment()
return fn(*args, **kwargs)
def xla_launch(fn):
# TODO: the accelerator should be optional to just launch processes, but this requires lazy initialization
accelerator = TPUAccelerator()
strategy = XLAStrategy(accelerator=accelerator, parallel_devices=list(range(8)))
launcher = _XLALauncher(strategy=strategy)
wrapped = partial(wrap_launch_function, fn, strategy)
return launcher.launch(wrapped, strategy)
def broadcast_on_tpu_fn(strategy):
obj = ("ver_0.5", "logger_name", strategy.local_rank)
result = strategy.broadcast(obj)
assert result == ("ver_0.5", "logger_name", 0)
@RunIf(tpu=True)
@mock.patch.dict(os.environ, os.environ.copy(), clear=True)
def test_broadcast_on_tpu():
"""Checks if an object from the main process is broadcasted to other processes correctly."""
xla_launch(broadcast_on_tpu_fn)
def tpu_reduce_fn(strategy):
with pytest.raises(ValueError, match="XLAStrategy only supports"):
strategy.all_reduce(1, reduce_op="undefined")
with pytest.raises(ValueError, match="XLAStrategy only supports"):
strategy.all_reduce(1, reduce_op=ReduceOp.MAX)
# it is faster to loop over here than to parameterize the test
for reduce_op in ("mean", "AVG", "sum", ReduceOp.SUM):
result = strategy.all_reduce(1, reduce_op=reduce_op)
if isinstance(reduce_op, str) and reduce_op.lower() in ("mean", "avg"):
assert result.item() == 1
else:
assert result.item() == 8
@RunIf(tpu=True)
@mock.patch.dict(os.environ, os.environ.copy(), clear=True)
def test_tpu_reduce():
"""Test tpu spawn all_reduce operation."""
xla_launch(tpu_reduce_fn)
@RunIf(tpu=True)
@mock.patch("lightning.fabric.strategies.xla.XLAStrategy.root_device")
def test_xla_mp_device_dataloader_attribute(_, monkeypatch):
dataset = RandomDataset(32, 64)
dataloader = DataLoader(dataset)
strategy = XLAStrategy()
isinstance_return = True
import torch_xla.distributed.parallel_loader as parallel_loader
class MpDeviceLoaderMock(MagicMock):
def __instancecheck__(self, instance):
# to make `isinstance(dataloader, MpDeviceLoader)` pass with a mock as class
return isinstance_return
mp_loader_mock = MpDeviceLoaderMock()
monkeypatch.setattr(parallel_loader, "MpDeviceLoader", mp_loader_mock)
processed_dataloader = strategy.process_dataloader(dataloader)
assert processed_dataloader is dataloader
mp_loader_mock.assert_not_called() # no-op
isinstance_return = False
processed_dataloader = strategy.process_dataloader(dataloader)
mp_loader_mock.assert_called_with(dataloader, strategy.root_device)
assert processed_dataloader.dataset == processed_dataloader._loader.dataset
assert processed_dataloader.batch_sampler == processed_dataloader._loader.batch_sampler
_loader = DataLoader(RandomDataset(32, 64))
_iterable_loader = DataLoader(RandomIterableDataset(32, 64))
_loader_no_len = CustomNotImplementedErrorDataloader(_loader)
@RunIf(tpu=True)
@pytest.mark.parametrize("dataloader", [None, _iterable_loader, _loader_no_len])
@mock.patch("lightning.fabric.strategies.xla.XLAStrategy.root_device")
def test_xla_validate_unsupported_iterable_dataloaders(_, dataloader, monkeypatch):
"""Test that the XLAStrategy validates against dataloaders with no length defined on datasets (iterable
dataset)."""
import torch_xla.distributed.parallel_loader as parallel_loader
monkeypatch.setattr(parallel_loader, "MpDeviceLoader", Mock())
with pytest.raises(TypeError, match="TPUs do not currently support"):
XLAStrategy().process_dataloader(dataloader)
def tpu_all_gather_fn(strategy):
for sync_grads in [True, False]:
tensor = torch.tensor(1.0, device=strategy.root_device, requires_grad=True)
result = strategy.all_gather(tensor, sync_grads=sync_grads)
summed = result.sum()
assert torch.equal(summed, torch.tensor(8.0))
summed.backward()
if sync_grads:
assert torch.equal(tensor.grad, torch.tensor(1.0))
else:
# As gradients are not synced, the original tensor will not have gradients.
assert tensor.grad is None
@RunIf(tpu=True)
@mock.patch.dict(os.environ, os.environ.copy(), clear=True)
def test_tpu_all_gather():
"""Test the all_gather operation on TPU."""
xla_launch(tpu_all_gather_fn)