[torch] Various improvements to `torch.distributed.launch` and `torch.distributed.run` (#60925)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/60925
* Make `torch.distributed.launch` restarts to 0
* Remove unnecessary `-use_env` warning, move `-use_env` warnings
* Move `-use_env` warnings to `torch.distributed.launch`
* Make default log level WARNING
* Add new doc section around transitioning to `torch.distributed.run`
* Make `torch.distributed.launch` not use error-propagation
* Set default events handler to `null` that does not print events to console
* Add reference from `torch.distributed.launch` to `torch.distributed.run`
* Set correct preexec function that sends SIGTERM to child processes when parent dies
Issues resolved:
https://github.com/pytorch/pytorch/issues/60716
https://github.com/pytorch/pytorch/issues/60754
Test Plan:
sandcastle
python -m torch.distributed.launch --nproc_per_node 2 main.py -> uses 0 restarts
python -m torch.distributed.run --nproc_per_node 2 main.py -> uses default for torchelastic, 0 restarts
python -m torch.distributed.launch --nproc_per_node=4 --use_env --no_python main.py -> produces error
python -m torch.distributed.launch --nproc_per_node=4 --use_env main.py -> no warning
python -m torch.distributed.launch --nproc_per_node=4 --no_python main.py ->warning
Output of running torch.distributed.launch without --use_env:
$path/torch/distributed/launch.py:173: FutureWarning: The module torch.distributed.launch is deprecated
and will be removed in future. Use torch.distributed.run.
Note that --use_env is set by default in torch.distributed.run.
If your script expects `--local_rank` argument to be set, please
change it to read from `os.environ('LOCAL_RANK')` instead.
New section:
{F628923078}
{F628974089}
Reviewed By: kiukchung, cbalioglu
Differential Revision: D29413019
fbshipit-source-id: 323bfbad9d0e4aba3b10ddd7a243ca6e48169630
