lightning/tests/plugins/test_sharded_plugin.py

526 lines
18 KiB
Python

import os
import platform
import time
from unittest import mock
import pytest
import torch
from torch.utils.data.distributed import DistributedSampler
from pytorch_lightning import Trainer, seed_everything
from pytorch_lightning.callbacks import Callback
from pytorch_lightning.plugins.sharded_native_amp_plugin import ShardedNativeAMPPlugin
from pytorch_lightning.plugins.sharded_plugin import DDPShardedPlugin, FAIRSCALE_AVAILABLE
from pytorch_lightning.utilities import NATIVE_AMP_AVALAIBLE
from tests.base.boring_model import BoringModel, RandomDataset
@mock.patch.dict(
os.environ,
{
"CUDA_VISIBLE_DEVICES": "0,1",
"SLURM_NTASKS": "2",
"SLURM_JOB_NAME": "SOME_NAME",
"SLURM_NODEID": "0",
"LOCAL_RANK": "0",
"SLURM_LOCALID": "0",
},
)
@mock.patch("torch.cuda.device_count", return_value=2)
@pytest.mark.parametrize(
["ddp_backend", "gpus", "num_processes"],
[("ddp_cpu", None, None), ("ddp", 2, 0), ("ddp2", 2, 0), ("ddp_spawn", 2, 0)],
)
@pytest.mark.skipif(not FAIRSCALE_AVAILABLE, reason="Fairscale is not available")
def test_ddp_choice_sharded(tmpdir, ddp_backend, gpus, num_processes):
"""
Test to ensure that plugin is correctly chosen
"""
class CB(Callback):
def on_fit_start(self, trainer, pl_module):
assert isinstance(trainer.accelerator_backend.ddp_plugin, DDPShardedPlugin)
raise SystemExit()
model = BoringModel()
trainer = Trainer(
fast_dev_run=True,
gpus=gpus,
num_processes=num_processes,
distributed_backend=ddp_backend,
plugins=[DDPShardedPlugin()],
callbacks=[CB()],
)
with pytest.raises(SystemExit):
trainer.fit(model)
@mock.patch.dict(
os.environ,
{
"CUDA_VISIBLE_DEVICES": "0,1",
"SLURM_NTASKS": "2",
"SLURM_JOB_NAME": "SOME_NAME",
"SLURM_NODEID": "0",
"LOCAL_RANK": "0",
"SLURM_LOCALID": "0",
},
)
@mock.patch("torch.cuda.device_count", return_value=2)
@pytest.mark.parametrize(
["ddp_backend", "gpus", "num_processes"],
[("ddp_cpu", None, None), ("ddp", 2, 0), ("ddp2", 2, 0), ("ddp_spawn", 2, 0)],
)
@pytest.mark.skipif(not FAIRSCALE_AVAILABLE, reason="Fairscale is not available")
@pytest.mark.skipif(not NATIVE_AMP_AVALAIBLE, reason="Requires native AMP")
def test_ddp_choice_sharded_amp(tmpdir, ddp_backend, gpus, num_processes):
"""
Test to ensure that plugin native amp plugin is correctly chosen when using sharded
"""
class CB(Callback):
def on_fit_start(self, trainer, pl_module):
assert isinstance(trainer.accelerator_backend.ddp_plugin, DDPShardedPlugin)
assert isinstance(trainer.precision_connector.backend, ShardedNativeAMPPlugin)
raise SystemExit()
model = BoringModel()
trainer = Trainer(
fast_dev_run=True,
gpus=gpus,
precision=16,
num_processes=num_processes,
distributed_backend=ddp_backend,
plugins=[DDPShardedPlugin()],
callbacks=[CB()],
)
with pytest.raises(SystemExit):
trainer.fit(model)
@pytest.mark.skipif(platform.system() == "Windows",
reason="Distributed training is not supported on Windows")
@pytest.mark.skipif(not FAIRSCALE_AVAILABLE, reason="Fairscale is not available")
def test_ddp_sharded_plugin_checkpoint_cpu(tmpdir):
"""
Test to ensure that checkpoint is saved correctly
"""
model = BoringModel()
trainer = Trainer(
accelerator='ddp_cpu',
plugins=[DDPShardedPlugin()],
fast_dev_run=True,
)
trainer.fit(model)
checkpoint_path = os.path.join(tmpdir, 'model.pt')
trainer.save_checkpoint(checkpoint_path)
saved_model = BoringModel.load_from_checkpoint(checkpoint_path)
# Assert model parameters are identical after loading
for ddp_param, shard_param in zip(model.parameters(), saved_model.parameters()):
assert torch.equal(ddp_param, shard_param)
@pytest.mark.skipif(torch.cuda.device_count() < 2, reason="test requires multi-GPU machine")
@pytest.mark.skipif(platform.system() == "Windows",
reason="Distributed training is not supported on Windows")
@pytest.mark.skipif(not FAIRSCALE_AVAILABLE, reason="Fairscale is not available")
def test_ddp_sharded_plugin_checkpoint_multi_gpu(tmpdir):
"""
Test to ensure that checkpoint is saved correctly when using multiple GPUs
"""
model = BoringModel()
trainer = Trainer(
gpus=2,
accelerator='ddp_spawn',
plugins=[DDPShardedPlugin()],
fast_dev_run=True,
)
trainer.fit(model)
checkpoint_path = os.path.join(tmpdir, 'model.pt')
trainer.save_checkpoint(checkpoint_path)
saved_model = BoringModel.load_from_checkpoint(checkpoint_path)
# Assert model parameters are identical after loading
for ddp_param, shard_param in zip(model.parameters(), saved_model.parameters()):
assert torch.equal(ddp_param, shard_param)
@pytest.mark.skipif(torch.cuda.device_count() < 2, reason="test requires multi-GPU machine")
@pytest.mark.skipif(platform.system() == "Windows",
reason="Distributed training is not supported on Windows")
@pytest.mark.skipif(not FAIRSCALE_AVAILABLE, reason="Fairscale is not available")
def test_ddp_sharded_plugin_finetune(tmpdir):
"""
Test to ensure that we can save and restart training (simulate fine-tuning)
"""
model = BoringModel()
trainer = Trainer(
gpus=2,
accelerator='ddp_spawn',
plugins=[DDPShardedPlugin()],
fast_dev_run=True,
)
trainer.fit(model)
checkpoint_path = os.path.join(tmpdir, 'model.pt')
trainer.save_checkpoint(checkpoint_path)
saved_model = BoringModel.load_from_checkpoint(checkpoint_path)
trainer = Trainer(
fast_dev_run=True,
)
trainer.fit(saved_model)
return 1
@pytest.mark.skipif(platform.system() == "Windows",
reason="Distributed training is not supported on Windows")
@pytest.mark.skipif(not FAIRSCALE_AVAILABLE, reason="Fairscale is not available")
def test_ddp_sharded_plugin_resume_from_checkpoint(tmpdir):
"""
Test to ensure that resuming from checkpoint works
"""
model = BoringModel()
trainer = Trainer(
accelerator='ddp_cpu',
plugins=[DDPShardedPlugin()],
fast_dev_run=True,
)
trainer.fit(model)
checkpoint_path = os.path.join(tmpdir, 'model.pt')
trainer.save_checkpoint(checkpoint_path)
model = BoringModel()
trainer = Trainer(
accelerator='ddp_cpu',
plugins=[DDPShardedPlugin()],
fast_dev_run=True,
resume_from_checkpoint=checkpoint_path
)
trainer.fit(model)
return 1
@pytest.mark.skip(reason="Currently unsupported restarting training on different number of devices.")
@pytest.mark.skipif(torch.cuda.device_count() < 2, reason="test requires multi-GPU machine")
@pytest.mark.skipif(platform.system() == "Windows",
reason="Distributed training is not supported on Windows")
@pytest.mark.skipif(not FAIRSCALE_AVAILABLE, reason="Fairscale is not available")
def test_ddp_sharded_plugin_resume_from_checkpoint_downsize_gpus(tmpdir):
"""
Test to ensure that resuming from checkpoint works when downsizing number of GPUS
"""
model = BoringModel()
trainer = Trainer(
accelerator='ddp_spawn',
plugins=[DDPShardedPlugin()],
fast_dev_run=True,
gpus=2,
)
trainer.fit(model)
checkpoint_path = os.path.join(tmpdir, 'model.pt')
trainer.save_checkpoint(checkpoint_path)
model = BoringModel()
trainer = Trainer(
accelerator='ddp_spawn',
plugins=[DDPShardedPlugin()],
fast_dev_run=True,
gpus=1,
resume_from_checkpoint=checkpoint_path
)
trainer.fit(model)
return 1
@pytest.mark.skipif(not torch.cuda.is_available(), reason="requires GPU machine")
@pytest.mark.skipif(platform.system() == "Windows",
reason="Distributed training is not supported on Windows")
@pytest.mark.skipif(not FAIRSCALE_AVAILABLE, reason="Fairscale is not available")
def test_ddp_sharded_plugin_resume_from_checkpoint_gpu_to_cpu(tmpdir):
"""
Test to ensure that resuming from checkpoint works when going from GPUs- > CPU
"""
model = BoringModel()
trainer = Trainer(
accelerator='ddp_spawn',
plugins=[DDPShardedPlugin()],
gpus=1,
fast_dev_run=True
)
trainer.fit(model)
checkpoint_path = os.path.join(tmpdir, 'model.pt')
trainer.save_checkpoint(checkpoint_path)
model = BoringModel()
trainer = Trainer(
plugins=[DDPShardedPlugin()],
accelerator='ddp_cpu',
fast_dev_run=True,
resume_from_checkpoint=checkpoint_path
)
trainer.fit(model)
return 1
@pytest.mark.skipif(platform.system() == "Windows",
reason="Distributed training is not supported on Windows")
@pytest.mark.skipif(not FAIRSCALE_AVAILABLE, reason="Fairscale is not available")
def test_ddp_sharded_plugin_correctness_one_device():
# Allow slightly slower speed due to one CPU doing additional sequential memory saving calls
run_sharded_correctness(accelerator='ddp_cpu', max_percent_speed_diff=0.5)
@pytest.mark.skipif(not torch.cuda.is_available(), reason="requires GPU machine")
@pytest.mark.skipif(platform.system() == "Windows",
reason="Distributed training is not supported on Windows")
@pytest.mark.skipif(not FAIRSCALE_AVAILABLE, reason="Fairscale is not available")
def test_ddp_sharded_plugin_correctness_one_gpu():
run_sharded_correctness(gpus=1, accelerator='ddp_spawn')
@pytest.mark.skipif(not NATIVE_AMP_AVALAIBLE, reason="Requires native AMP")
@pytest.mark.skipif(not torch.cuda.is_available(), reason="requires GPU machine")
@pytest.mark.skipif(platform.system() == "Windows",
reason="Distributed training is not supported on Windows")
@pytest.mark.skipif(not FAIRSCALE_AVAILABLE, reason="Fairscale is not available")
def test_ddp_sharded_plugin_correctness_amp_one_gpu():
run_sharded_correctness(gpus=1, precision=16, accelerator='ddp_spawn')
@pytest.mark.skipif(torch.cuda.device_count() < 2, reason="test requires multi-GPU machine")
@pytest.mark.skipif(platform.system() == "Windows",
reason="Distributed training is not supported on Windows")
@pytest.mark.skipif(not FAIRSCALE_AVAILABLE,
reason="Fairscale is not available")
def test_ddp_sharded_plugin_correctness_multi_gpu():
run_sharded_correctness(gpus=2, accelerator='ddp_spawn')
@pytest.mark.skipif(not NATIVE_AMP_AVALAIBLE, reason="Requires native AMP")
@pytest.mark.skipif(platform.system() == "Windows",
reason="Distributed training is not supported on Windows")
@pytest.mark.skipif(torch.cuda.device_count() < 2, reason="test requires multi-GPU machine")
@pytest.mark.skipif(not FAIRSCALE_AVAILABLE, reason="Fairscale is not available")
def test_ddp_sharded_plugin_correctness_amp_multi_gpu():
run_sharded_correctness(gpus=2, precision=16, accelerator='ddp_spawn')
@pytest.mark.skipif(torch.cuda.device_count() < 2, reason="test requires multi-GPU machine")
@pytest.mark.skipif(platform.system() == "Windows",
reason="Distributed training is not supported on Windows")
@pytest.mark.skipif(not FAIRSCALE_AVAILABLE,
reason="Fairscale is not available")
def test_ddp_sharded_plugin_correctness_multi_gpu_multi_optim():
"""
Ensures same results using multiple optimizers across multiple GPUs
"""
run_sharded_correctness(
gpus=2,
accelerator='ddp_spawn',
model_cls=TestMultipleOptimizersModel,
max_percent_speed_diff=0.3 # Increase speed diff since only 2 GPUs sharding 2 optimizers
)
@pytest.mark.skip(reason="Currently DDP manual optimization is broken due to no reduce within training step.")
@pytest.mark.skipif(torch.cuda.device_count() < 2, reason="test requires multi-GPU machine")
@pytest.mark.skipif(platform.system() == "Windows",
reason="Distributed training is not supported on Windows")
@pytest.mark.skipif(not FAIRSCALE_AVAILABLE,
reason="Fairscale is not available")
@mock.patch.dict(os.environ, {"PL_DEV_DEBUG": "1"})
def test_ddp_sharded_plugin_correctness_multi_gpu_multi_optim_manual(tmpdir):
"""
Ensures using multiple optimizers across multiple GPUs with manual optimization
"""
run_sharded_correctness(
gpus=2,
accelerator='ddp_spawn',
model_cls=TestManualModel,
)
class TestModel(BoringModel):
"""
Overrides training loader to ensure we enforce the same seed for all DDP processes.
"""
def train_dataloader(self):
seed_everything(42)
return torch.utils.data.DataLoader(RandomDataset(32, 64))
class TestManualModel(TestModel):
def training_step(self, batch, batch_idx, optimizer_idx):
# manual
(opt_a, opt_b) = self.optimizers()
loss_1 = self.step(batch)
self.manual_backward(loss_1, opt_a)
self.manual_optimizer_step(opt_a)
# fake discriminator
loss_2 = self.step(batch[0])
# ensure we forward the correct params to the optimizer
# without retain_graph we can't do multiple backward passes
self.manual_backward(loss_2, opt_b, retain_graph=True)
self.manual_backward(loss_2, opt_a, retain_graph=True)
self.manual_optimizer_step(opt_b)
assert self.layer.weight.grad is None or torch.all(self.layer.weight.grad == 0)
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
@property
def automatic_optimization(self) -> bool:
return False
class TestMultipleOptimizersModel(TestModel):
def training_step(self, batch, batch_idx, optimizer_idx):
output = self.layer(batch)
loss = self.loss(batch, output)
return {"loss": 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
def record_ddp_fit_model_stats(trainer, model, gpus):
"""
Helper to calculate wall clock time for fit + max allocated memory.
Args:
trainer: The trainer object.
model: The LightningModule.
gpus: Number of GPUs in test.
Returns:
Max Memory if using GPUs, and total wall clock time.
"""
max_memory = None
time_start = time.perf_counter()
if gpus > 0:
torch.cuda.reset_peak_memory_stats()
torch.cuda.synchronize()
trainer.fit(model)
if gpus > 0:
torch.cuda.synchronize()
max_memory = torch.cuda.max_memory_allocated() / 2 ** 20
total_time = time.perf_counter() - time_start
return max_memory, total_time
def run_sharded_correctness(
accelerator='ddp_spawn',
gpus=0,
precision=32,
max_percent_speed_diff=0.25,
model_cls=TestModel):
"""
Ensures that the trained model is identical to the standard DDP implementation.
Also checks for speed/memory regressions, we should expect always less memory but performance to fluctuate.
Args:
accelerator: Accelerator type for test.
gpus: Number of GPUS to enable.
precision: Whether to use AMP or normal FP32 training.
max_percent_speed_diff: The maximum speed difference compared to normal DDP training.
This is more a safety net for variability in CI which can vary in speed, not for benchmarking.
model_cls: Model class to use for test.
"""
# Train normal DDP
seed_everything(42)
ddp_model = model_cls()
trainer = Trainer(
fast_dev_run=True,
max_epochs=1,
gpus=gpus,
precision=precision,
accelerator=accelerator,
)
max_ddp_memory, ddp_time = record_ddp_fit_model_stats(
trainer=trainer,
model=ddp_model,
gpus=gpus
)
# Reset and train sharded DDP
seed_everything(42)
sharded_model = model_cls()
trainer = Trainer(
fast_dev_run=True,
max_epochs=1,
gpus=gpus,
precision=precision,
accelerator=accelerator,
plugins=[DDPShardedPlugin()],
)
max_sharded_memory, sharded_time = record_ddp_fit_model_stats(
trainer=trainer,
model=sharded_model,
gpus=gpus
)
# Assert model parameters are identical after fit
for ddp_param, shard_param in zip(ddp_model.parameters(), sharded_model.parameters()):
assert torch.equal(ddp_param, shard_param), 'Model parameters are different between DDP and Sharded plugin'
# Assert speed parity by ensuring percentage difference between sharded/ddp is below threshold
percent_diff = (sharded_time - ddp_time) / sharded_time
assert percent_diff <= max_percent_speed_diff, \
f'Sharded plugin was too slow compared to DDP, Sharded Time: {sharded_time}, DDP Time: {ddp_time}'
if gpus > 0:
# Assert CUDA memory parity
assert max_sharded_memory <= max_ddp_memory, \
f'Sharded plugin used too much memory compared to DDP,' \
f'Sharded Mem: {max_sharded_memory}, DDP Mem: {max_ddp_memory}'