Enhance the documentation for torch.nn.DataParallel (#15993)
Summary:
I found a few sentences in DataParallel docstring confusing, so I suggest this enhancement.
- Arbitrary arguments are allowed to be passed .... *INCLUDING* tensors (Not *EXCLUDING*)
- The original author said that "other types" are shallow-copied but I think actually only some builtin types are (effectively) shallow-copied. And "other types" are shared. Here is an example.
```python
import torch
from torch.nn import Module, DataParallel
from collections import deque
class MyModel(Module):
def forward(self, x):
x.append(None)
model = MyModel(); model.cuda()
model = DataParallel(model)
d = deque()
model.forward(d)
print(d)
```
This is a side note.
As far as I know, copying objects is not a specially frequent operation in python unlike some other languages. Notably, no copying is involved in assignment or function parameter passing. They are only name bindings and it is the whole point of "everything is object" python philosophy, I guess. If one keep this in mind, it may help you dealing with things like multithreading.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15993
Differential Revision: D14020404
Pulled By: ezyang
fbshipit-source-id: a38689c94d0b8f77be70447f34962d3a7cd25e2e
