Fix issue 1721 by always initializing process group. #1722
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This pull request fixes issue #1721, where single GPU training/inference may error if the worker uses
torch.dist
. In summary, it makes sure the default process group is always initialized as long asworld_size > 0
, otherwise it raises aValueError
to indicate illegal argument(s). The existing code should not be affected, as stated in issue #1721.Rationale: Always initializing the process group is preferred, because when
launch
is called, the user most likely requests distributed semantics. This fix makes the user code consistent by allowing the users to maketorch.dist
calls even if there is only one GPU.