NVIDIA / NVIDIA/apex

deepcopy DistributedDataParallel loss actual model

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#451 2 comments 1 reaction 0 assignees View on GitHub

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Dominant language
Python
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Description

model = nn.Linear(10, 2).cuda()
torch_wrapper = torch.data.parallel.DistributedDataParallel(model)
apex_wrapper = apex.parallel.DistributedDataParallel(model)

lhs = copy.deepcopy(torch_wrapper).module  # ok
rhs = copy.deepcopy(apex_wrapper).module  # failed, AttributeError: 'DistributedDataParallel' object has no attribute 'module'

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Research direction

Start by running the Python reproduction with torch and apex DistributedDataParallel wrappers and compare the deepcopy results. Trace how the apex wrapper exposes the wrapped model after copying, then add regression coverage showing that the copied wrapper provides the expected underlying model access.

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Assessment

Tech stack
python, pytorch
Domain
distributed-systems, machine-learning
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
38/100

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