Add barriers after init_process_group() for all recipes

[datumbox]

Currently only the detection recipe supports this:

vision/references/detection/utils.py

Lines 278 to 281 in d367a01

	torch.distributed.init_process_group(
	backend=args.dist_backend, init_method=args.dist_url, world_size=args.world_size, rank=args.rank
	)
	torch.distributed.barrier()

Adding barriers to all other recipes.

@mrshenli clarified offline that in theory, we shouldn't need that, as init_process_group already performed a store-based barrier (see here). The dist.barrier is basically an empty allreduce. But to be on the safe side, we opted for adding this in all references.

[facebook-github-bot]

💊 CI failures summary and remediations

As of commit de22c07 (more details on the Dr. CI page):

---

• 1/1 failures introduced in this PR

---

1 failure not recognized by patterns:

Job	Step	Action
cmake_macos_cpu	curl -o conda.sh https://repo.anaconda.com/miniconda/Miniconda3-latest-MacOSX-x86_64.sh
sh conda.sh -b
source $HOME/miniconda3/bin/activate
conda install -yq conda-build cmake
packaging/build_cmake.sh
	🔁 rerun

---

This comment was automatically generated by Dr. CI (expand for details).

Please report bugs/suggestions to the (internal) Dr. CI Users group.

Click here to manually regenerate this comment.

[mrshenli]

LGTM