Update DDP for torch.distributed.run with gloo backend (#3680)

* Update DDP for `torch.distributed.run`

* Add LOCAL_RANK

* remove opt.local_rank

* backend="gloo|nccl"

* print

* print

* debug

* debug

* os.getenv

* gloo

* gloo

* gloo

* cleanup

* fix getenv

* cleanup

* cleanup destroy

* try nccl

* return opt

* add --local_rank

* add timeout

* add init_method

* gloo

* move destroy

* move destroy

* move print(opt) under if RANK

* destroy only RANK 0

* move destroy inside train()

* restore destroy outside train()

* update print(opt)

* cleanup

* nccl

* gloo with 60 second timeout

* update namespace printing

models/export.py

@@ -163,8 +163,8 @@ def parse_opt():
 
 
 def main(opt):
-    print(opt)
     set_logging()
+    print(colorstr('export: ') + ', '.join(f'{k}={v}' for k, v in vars(opt).items()))
     export(**vars(opt))