pytorch/test/distributed/test_c10d_spawn.py
Junjie Wang 7c2489bdae [PyTorch][Distributed] Enable Reduce Scatter and modify all_to_all for sharded linear with more test cases. (#68786)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/68786

To enable the auto grad for the sharded linear, we find we need to make some changes to the current nn function api (c10d api with auto grad enabled). So we made the following several changes:

1. Add a new api `reduce_scatter` since we need it in the rowwise sharding.
2. Modify the `all_to_all` api to make sure it consistent with the ones in distributed_c10d.py.
3. Found the cpp input params of `reduce_scatter` is missing input param, added more unit test to cover these cases.
4. Sync the NN test from gloo to nccl.
ghstack-source-id: 144860208

Test Plan: CI + Unit Test

Reviewed By: pritamdamania87

Differential Revision: D32569674

fbshipit-source-id: 9bd613f91bbf7a39eede0af32a5a5db0f2ade43b
2021-12-06 13:38:58 -08:00

253 lines
9.2 KiB
Python

# Owner(s): ["oncall: distributed"]
import os
import sys
import tempfile
import torch
import torch.distributed as c10d
import torch.multiprocessing as mp
from torch.testing._internal.common_distributed import \
MultiProcessTestCase
from torch.testing._internal.common_utils import load_tests,\
NO_MULTIPROCESSING_SPAWN
# Torch distributed.nn is not available in windows
# check #42095, it errors on import.
_torch_dist_nn_available = True
try:
import torch.distributed.nn
except ImportError:
_torch_dist_nn_available = False
# load_tests from common_utils is used to automatically filter tests for
# sharding on sandcastle. This line silences flake warnings
load_tests = load_tests
if not c10d.is_available():
print('c10d not available, skipping tests', file=sys.stderr)
sys.exit(0)
if NO_MULTIPROCESSING_SPAWN:
print('spawn not available, skipping tests', file=sys.stderr)
sys.exit(0)
class AbstractProcessGroupShareTensorTest(object):
world_size = 2
def _test_multiprocess(self, f, shared_tensors, init_pg, n_output):
ws = self.world_size
# file store will delete the test file on destruction
file = tempfile.NamedTemporaryFile(delete=False)
ctx = mp.get_context('spawn')
c2p = ctx.Queue(2)
p2c = ctx.Queue(2)
ps = []
for i in range(ws):
p = ctx.Process(
target=f,
args=(i, file.name, shared_tensors, ws, init_pg, c2p, p2c))
p.start()
ps.append(p)
for _ in range(ws * n_output):
pid, expected, result = c2p.get()
self.assertEqual(
expected,
result,
msg=(
"Expect rank {} to receive tensor {} but got {}."
).format(pid, expected, result)
)
for _ in range(ws):
p2c.put(0)
for p in ps:
p.join(2)
# Why classmethod? multiprocessing cannot pickle TestCase subclass when in
# spawn mode. See https://bugs.python.org/issue33884.
@classmethod
def _test_broadcast_process(
cls, rank, filename, shared_tensors, world_size, init_pg, c2p, p2c):
pg = init_pg(rank, filename, world_size)
xs = [shared_tensors[rank]]
pg.broadcast(xs).wait()
c2p.put((rank, torch.zeros(2, 2), xs[0].to("cpu")))
p2c.get()
@classmethod
def _test_allreduce_process(
cls, rank, filename, shared_tensors, world_size, init_pg, c2p, p2c):
pg = init_pg(rank, filename, world_size)
xs = [shared_tensors[rank]]
pg.allreduce(xs, op=c10d.ReduceOp.SUM).wait()
c2p.put((rank, torch.ones(2, 2) * 2, xs[0].to("cpu")))
p2c.get()
@classmethod
def _test_allgather_process(
cls, rank, filename, shared_tensors, world_size, init_pg, c2p, p2c):
pg = init_pg(rank, filename, world_size)
xs = [shared_tensors[rank]]
ys = [[torch.zeros_like(xs[0]) for i in range(world_size)]]
pg.allgather(ys, xs).wait()
for i in range(world_size):
c2p.put((rank, torch.ones(2, 2) * i, ys[0][i].to("cpu")))
p2c.get()
class TestDistributedNNFunctions(MultiProcessTestCase):
def setUp(self):
super(TestDistributedNNFunctions, self).setUp()
self._spawn_processes()
def tearDown(self):
super(TestDistributedNNFunctions, self).tearDown()
try:
os.remove(self.file_name)
except OSError:
pass
@property
def op_timeout_sec(self):
return 1
@property
def world_size(self):
return 2
def _test_broadcast(self, backend):
store = c10d.FileStore(self.file_name, self.world_size)
# This is required because these functions calls directly to the .dist and needs
# the world to be initialized
c10d.init_process_group(
store=store, rank=self.rank, world_size=self.world_size, backend=backend
)
device = torch.device(f"cuda:{self.rank}")
x = torch.ones(5, 5, device=device) + self.rank
x.requires_grad = True
y = torch.distributed.nn.broadcast(x, 1)
self.assertEqual(y, 1 + torch.ones(5, 5))
z = y.sin().sum()
z.backward()
# We can't check the gradient of communications numerically so we have to do some calculations
if self.rank == 1:
self.assertEqual(x.grad, 2 * torch.cos(x))
elif self.rank == 0:
self.assertEqual(x.grad, torch.zeros(5, 5, device=device))
def _test_reduce(self, backend):
store = c10d.FileStore(self.file_name, self.world_size)
# This is required because these functions calls directly to the .dist and needs
# the world to be initialized
c10d.init_process_group(
store=store, rank=self.rank, world_size=self.world_size, backend=backend
)
device = torch.device(f"cuda:{self.rank}")
x = torch.ones(5, 5, device=device) + self.rank
x.requires_grad = True
y = torch.distributed.nn.reduce(x, 1, op=c10d.ReduceOp.SUM)
if self.rank == 1:
self.assertEqual(y, 3 * torch.ones(5, 5, device=device))
z = y.sin().sum()
z.backward()
# Gradients are broadcasted to both ranks
x_g = (3 * torch.ones(5, 5, device=device)).cos()
self.assertEqual(x.grad, x_g)
def _test_allreduce(self, backend):
store = c10d.FileStore(self.file_name, self.world_size)
# This is required because these functions calls directly to the .dist and needs
# the world to be initialized
c10d.init_process_group(
store=store, rank=self.rank, world_size=self.world_size, backend=backend
)
device = torch.device(f"cuda:{self.rank}")
x = torch.ones(5, 5, device=device) + self.rank
x.requires_grad = True
y = torch.distributed.nn.all_reduce(x, op=c10d.ReduceOp.SUM)
self.assertEqual(y, 3 * torch.ones(5, 5, device=device))
z = y.sin().sum()
z.backward()
x_g = 2 * (3 * torch.ones(5, 5, device=device)).cos()
self.assertEqual(x.grad, x_g)
def _test_all_gather(self, backend):
store = c10d.FileStore(self.file_name, self.world_size)
# This is required because these functions calls directly to the .dist and needs
# the world to be initialized
c10d.init_process_group(
store=store, rank=self.rank, world_size=self.world_size, backend=backend
)
device = torch.device(f"cuda:{self.rank}")
x = torch.ones(5, 5, device=device) + self.rank
x.requires_grad = True
tensors = torch.distributed.nn.all_gather(x)
for i, t in enumerate(tensors):
self.assertEqual(t, torch.ones(5, 5, device=device) + i)
y = torch.sum(torch.stack(tensors), axis=0)
z = y.sin().sum()
z.backward()
x_s = 2 * (3 * torch.ones(5, 5, device=device)).cos()
self.assertEqual(x.grad, x_s)
def _test_all_to_all(self, backend):
store = c10d.FileStore(self.file_name, self.world_size)
# This is required because these functions calls directly to the .dist and needs
# the world to be initialized
c10d.init_process_group(
store=store, rank=self.rank, world_size=self.world_size, backend=backend
)
device = torch.device(f"cuda:{self.rank}")
x0 = torch.ones(5, 5, device=device) + 2 * self.rank
x1 = torch.ones(5, 5, device=device) + 2 * self.rank
x0.requires_grad = True
x1.requires_grad = True
y0 = torch.empty_like(x0)
y1 = torch.empty_like(x1)
tensors = torch.distributed.nn.all_to_all([y0, y1], [x0, x1])
for i, t in enumerate(tensors):
self.assertEqual(t, torch.ones(5, 5, device=device) + 2 * i)
y = torch.sum(torch.stack(tensors), axis=0)
z = y.sin().sum()
z.backward()
x_s = (4 * torch.ones(5, 5, device=device)).cos()
self.assertEqual(x0.grad, x_s)
self.assertEqual(x1.grad, x_s)
def _test_all_to_all_single(self, backend):
store = c10d.FileStore(self.file_name, self.world_size)
# This is required because these functions calls directly to the .dist and needs
# the world to be initialized
c10d.init_process_group(
store=store, rank=self.rank, world_size=self.world_size, backend=backend
)
device = torch.device(f"cuda:{self.rank}")
row = self.world_size * (self.rank + 1) * (self.world_size + 1) / 2
x = torch.ones(int(row), 5, device=device) * (self.rank + 1)
x.requires_grad = True
y = torch.empty_like(x)
split_sizes = [(i + 1) * (self.rank + 1) for i in range(self.world_size)]
y = torch.distributed.nn.all_to_all_single(
y, x, output_split_sizes=split_sizes, input_split_sizes=split_sizes
)
expected = []
for idx, tensor in enumerate(torch.split(x, split_sizes)):
expected.append(torch.full_like(tensor, (idx + 1)))
expected = torch.cat(expected)
self.assertEqual(y, expected)
z = y.sin().sum()
z.backward()
x_s = ((self.rank + 1) * torch.ones(int(row), 5, device=device)).cos()
self.assertEqual(x.grad, x_s)