pytorch

41966057 - helper function to print out all DDP-relevant env vars (#41297)

helper function to print out all DDP-relevant env vars (#41297) Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/41297 GH issue: https://github.com/pytorch/pytorch/issues/40105 Add a helper function to DDP to print out all relevant env vars for debugging Test Plan: test through unittest, example output: --- env:RANK=3 env:LOCAL_RANK=N/A env:WORLD_SIZE=N/A env:MASTER_PORT=N/A env:MASTER_ADDR=N/A env:CUDA_VISIBLE_DEVICES=N/A env:GLOO_SOCKET_IFNAME=N/A env:GLOO_DEVICE_TRANSPORT=N/A env:NCCL_SOCKET_IFNAME=N/A env:NCCL_BLOCKING_WAIT=N/A ... --- Reviewed By: mrshenli Differential Revision: D22490486 fbshipit-source-id: 5dc7d2a18111e5a5a12a1b724d90eda5d35acd1c