DDP is not working for me...
🐛 Bug
I run mnist example code in this repo.
When i excuted mnist.py, I could see one gpu's usage is 100% and this process is not finished.
After change ddp to ddp_spawn, It works.
But I want to use ddp!
To Reproduce
Steps to reproduce the behavior:
Run mnist.py.
Environment
script : mnist.py.
You can get the script and run it with:
python mnist.py --batch_size 128 --max_epochs 2 --gpus '0,1' --distributed_backend 'ddp' 


PyTorch Version (e.g., 1.0): 1.6.0+cu101
OS (e.g., Linux): Ubuntu 18.04 (Linux)
How you installed PyTorch (conda, pip, source): pip
Build command you used (if compiling from source): No
Python version: 3.6.9
CUDA/cuDNN version: 10.1/7.6.4
GPU models and configuration: Geforce 1080
Any other relevant information:

Additional context