pytorch/test/distributed/_composable/test_checkpoint.py
2025-01-22 04:48:28 +00:00

335 lines
11 KiB
Python

# Owner(s): ["oncall: distributed"]
import unittest
from collections import deque, OrderedDict
from contextlib import ContextDecorator, contextmanager, nullcontext
from copy import deepcopy
from functools import partial
import torch
import torch.nn as nn
from torch.distributed._composable import checkpoint
from torch.testing._internal.common_cuda import TEST_CUDA
from torch.testing._internal.common_utils import run_tests, TestCase
from torch.utils.checkpoint import CheckpointError
class MemoryDelta(ContextDecorator):
def __init__(self, device: torch.device):
self.device: torch.device = device
self.active_memory_enter: int = 0
self.active_memory_exit: int = 0
def __enter__(self):
self.active_memory_enter = (
torch.cuda.memory_stats()["active_bytes.all.current"]
if self.device.type == "cuda"
else 0
)
return self
def __exit__(self, *exc):
self.active_memory_exit = (
torch.cuda.memory_stats()["active_bytes.all.current"]
if self.device.type == "cuda"
else 0
)
def delta(self) -> int:
return self.active_memory_exit - self.active_memory_enter
class ToyModel(nn.Module):
def __init__(self) -> None:
super().__init__()
self.l1 = nn.Linear(100, 100)
self.seq = nn.Sequential(
nn.ReLU(),
nn.Linear(100, 100),
nn.ReLU(),
)
def forward(self, x):
return self.seq(self.l1(x))
class RandomModel(nn.Module):
def __init__(self) -> None:
super().__init__()
self.p = nn.Parameter(torch.randn(100, 100))
def forward(self, x):
y = torch.matmul(self.p, torch.randn(100, 100, device=self.p.device))
return torch.matmul(x, y)
class MultiOutputModel(nn.Module):
def __init__(self, device: torch.device):
super().__init__()
self.w1 = nn.Parameter(torch.randn((100, 100), device=device))
self.w2 = nn.Parameter(torch.randn((100, 100), device=device))
def forward(self, x: torch.Tensor) -> tuple[torch.Tensor, torch.Tensor]:
z = x @ self.w1
z = nn.functional.relu(z)
z = z @ self.w2
return z.sin(), z.cos()
class MultiInputModel(nn.Module):
def __init__(self, device: torch.device):
super().__init__()
self.w = nn.Parameter(torch.randn((100, 100), device=device))
def forward(self, xs: tuple[torch.Tensor, torch.Tensor]) -> torch.Tensor:
assert len(xs) == 2, f"Expects 2 args but got {len(xs)}"
x, y = xs
z = x + y
z = z @ self.w
return nn.functional.relu(z)
class TestCheckpoint(TestCase):
def _get_graph_size(self, out: torch.Tensor) -> int:
q = deque([out.grad_fn])
num_functions = 0
while len(q):
fn = q.pop()
num_functions += 1
for next_fn, _ in fn.next_functions:
if next_fn:
q.append(next_fn)
return num_functions
def _test_tensor_only(
self,
net: nn.Module,
x: torch.Tensor,
) -> None:
x1 = x.clone()
x2 = x.clone()
x1.requires_grad = True
x2.requires_grad = True
net1 = net
net2 = deepcopy(net)
# no checkpoint
with MemoryDelta(x.device) as mem1:
loss1 = net1(x1).sum()
loss1.backward()
# with checkpoint
checkpoint(net2.seq)
with MemoryDelta(x.device) as mem2:
loss2 = net2(x2).sum()
loss2.backward()
if x.is_cuda:
self.assertTrue(mem2.delta() < mem1.delta())
for p1, p2 in zip(net1.parameters(), net2.parameters()):
self.assertEqual(p1.grad, p2.grad)
def test_tensor_only_cpu(self):
x = torch.randn(20, 100)
net = ToyModel()
self._test_tensor_only(net, x)
@unittest.skipIf(not TEST_CUDA, "no cuda")
def test_tensor_only_gpu(self):
x = torch.randn(20, 100, device="cuda:0")
net = ToyModel().to("cuda:0")
self._test_tensor_only(net, x)
def test_random_cpu(self):
x1 = torch.randn(20, 100, requires_grad=True)
x2 = x1.clone()
net1 = RandomModel()
net2 = deepcopy(net1)
cpu_rng_state = torch.get_rng_state()
net1(x1).sum().backward()
torch.set_rng_state(cpu_rng_state)
checkpoint(net2)(x2).sum().backward()
for p1, p2 in zip(net1.parameters(), net2.parameters()):
self.assertEqual(p1.grad, p2.grad)
def test_multi_args(self):
"""
Tests checkpoint for modules with multiple output args and hence
multiple backward function input args.
"""
device = torch.device("cpu")
net1 = nn.Sequential(
MultiOutputModel(device),
MultiInputModel(device),
MultiOutputModel(device),
MultiInputModel(device),
)
net2 = deepcopy(net1)
checkpoint(net2[0])
checkpoint(net2[2])
x1 = torch.randn(20, 100, requires_grad=True)
x2 = x1.clone()
net1(x1).sum().backward()
net2(x2).sum().backward()
for p1, p2 in zip(net1.parameters(), net2.parameters()):
self.assertEqual(p1.grad, p2.grad)
def test_clears_state_on_error_in_forward(self):
class MyModel(torch.nn.Module):
def __init__(self, raise_in_recomp):
super().__init__()
self.fwd_count = 0
self.raise_in_recomp = raise_in_recomp
self.a = torch.nn.Linear(2, 2)
def forward(self, x):
if self.raise_in_recomp and self.fwd_count == 1:
raise RuntimeError("foo")
else:
if not self.raise_in_recomp:
# raise in the first forward
raise RuntimeError("foo")
self.fwd_count += 1
return self.a(x)
m = MyModel(raise_in_recomp=True)
m_seq = torch.nn.Sequential(OrderedDict({"m": m}))
checkpoint(m_seq.m)
inp = torch.randn(1, 2)
out = m_seq(inp).sum()
# Should raise in forward recomputation
with self.assertRaisesRegex(RuntimeError, "foo"):
out.backward()
# Check that _ac_generator is cleared out
self.assertEqual(None, checkpoint.state(m)._ac_generator)
m = MyModel(raise_in_recomp=False)
checkpoint(m)
inp = torch.randn(1, 2)
# Should raise in first forward
with self.assertRaises(RuntimeError):
m(inp)
self.assertEqual(None, checkpoint.state(m)._ac_generator)
def test_checkpoint_kwargs(self):
class MyModel(torch.nn.Module):
def __init__(self, raise_exp: bool, change_shape_in_recomp: bool):
super().__init__()
self.fwd_count = 0
self.raise_exp = raise_exp
self.change_shape_in_recomp = change_shape_in_recomp
self.a = torch.nn.Linear(2, 2)
def forward(self, x):
if self.raise_exp and self.fwd_count == 0:
raise RuntimeError("foo")
if self.raise_exp and self.fwd_count == 1:
raise RuntimeError("bar")
if self.change_shape_in_recomp and self.fwd_count == 1:
x.relu_()
random_tensor = torch.randn(1, 2)
x = self.a(x + random_tensor)
self.fwd_count += 1
return x
m = MyModel(True, False)
m0, m1, m2, m3 = (deepcopy(m) for _ in range(4))
# composable checkpoint does not support use_reentrant=True
with self.assertRaisesRegex(
NotImplementedError,
"use_reentrant=True is not supported in composable checkpoint. "
"Please use torch.utils.checkpoint.checkpoint instead.",
):
checkpoint(m, use_reentrant=True)
# check giving an unsupported kwarg
with self.assertRaisesRegex(ValueError, "Unexpected keyword arguments: foo"):
checkpoint(m0, foo="bar")
handled_fwd_exp = False
handled_recomp_exp = False
@contextmanager
def fwd_ctx(mod: MyModel):
try:
mod.raise_exp = False
yield
finally:
nonlocal handled_fwd_exp
handled_fwd_exp = True
mod.raise_exp = True
@contextmanager
def recomp_ctx(mod: MyModel):
try:
mod.raise_exp = False
yield
finally:
nonlocal handled_recomp_exp
handled_recomp_exp = True
mod.raise_exp = True
# Test different context functions
x = torch.randn(1, 2, requires_grad=True)
checkpoint(
m1, context_fn=lambda: (partial(fwd_ctx, m1)(), partial(recomp_ctx, m1)())
)
m1(x.clone()).sum().backward()
self.assertEqual((handled_fwd_exp, handled_recomp_exp), (True, True))
checkpoint(m2, context_fn=lambda: (nullcontext(), partial(recomp_ctx, m2)()))
with self.assertRaisesRegex(RuntimeError, "foo"):
m2(x.clone())
handled_fwd_exp = False # Reset flag
checkpoint(m3, context_fn=lambda: (partial(fwd_ctx, m3)(), nullcontext()))
with self.assertRaisesRegex(RuntimeError, "bar"):
m3(x.clone()).sum().backward()
self.assertEqual(handled_fwd_exp, True)
# Test determinism check failure
m4 = MyModel(False, True)
m5 = deepcopy(m4)
# Determinism check should not throw an error,
# but autograd should throw a RuntimeError
checkpoint(m4, determinism_check="none")
with self.assertRaises(RuntimeError):
m4(x.clone()).sum().backward()
# Determinism check should throw a CheckpointError
checkpoint(m5, determinism_check="default")
with self.assertRaises(CheckpointError):
m5(x.clone()).sum().backward()
# Test preserving random state
m6 = MyModel(False, False)
m7, m8 = (deepcopy(m6) for _ in range(2))
checkpoint(m7, preserve_rng_state=False)
checkpoint(m8, preserve_rng_state=True)
for mi in (m6, m7, m8):
torch.manual_seed(42)
loss = mi(x.clone()).sum()
torch.manual_seed(41)
loss.backward()
# check that m6 and m7 have at least one different grad
self.assertNotEqual(
(p1.grad for p1 in m6.parameters()), (p2.grad for p2 in m7.parameters())
)
# check that m6 and m8 have identical grads
for p1, p2 in zip(m6.parameters(), m8.parameters()):
self.assertEqual(p1.grad, p2.grad)
if __name__ == "__main__":
run_tests()