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Fix sharing of empty tensor in multiprocessing #6229

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Merged
soumith merged 1 commit into from
Apr 3, 2018
Merged

Fix sharing of empty tensor in multiprocessing #6229

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16 changes: 16 additions & 0 deletions test/test_multiprocessing.py
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Original file line number Diff line number Diff line change
Expand Up @@ -371,6 +371,22 @@ def test_event(self):
self.assertEqual(list(tensor), [4, 4, 4, 4])
p.join()

def _test_empty_tensor_sharing(self, dtype):
q = mp.Queue()
empty = torch.tensor([], dtype=dtype)
q.put(empty)
out = q.get(timeout=1)
self.assertEqual(out, empty)

def test_empty_tensor_sharing(self):
self._test_empty_tensor_sharing(torch.float32)
self._test_empty_tensor_sharing(torch.int64)

@unittest.skipIf(not torch.cuda.is_available(), 'CUDA not available')
def test_empty_tensor_sharing_cuda(self):
self._test_empty_tensor_sharing(torch.cuda.float32)
self._test_empty_tensor_sharing(torch.cuda.int64)

def _test_autograd_sharing(self, var):
ready = mp.Event()
master_modified = mp.Event()
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8 changes: 8 additions & 0 deletions torch/multiprocessing/reductions.py
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Expand Up @@ -98,6 +98,10 @@ def rebuild_storage_cuda(cls, device, handle, size, offset, view_size):
return storage


def rebuild_storage_empty(cls):
return cls()


def reduce_storage(storage):
from . import get_sharing_strategy
if storage.is_cuda:
Expand All @@ -109,6 +113,10 @@ def reduce_storage(storage):
cache_key = metadata[1]
rebuild = rebuild_storage_filename
storage._shared_incref()
elif storage.size() == 0:
# This is special cased because Empty tensors
# (with size 0) cannot be mmapped.
return (rebuild_storage_empty, (type(storage),))
else:
fd, size = storage._share_fd_()
if sys.version_info[0] == 2:
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