Multiple GPUs DDP error

[HarryXD2018]

Hi, when I was trying to train the model (train.train_diffusion.py)with multiple GPUs (tested on V100s and 2080Tis), I ran into the error below:

DDP RuntimeError: Default process group has not been initialized, please make sure to call init_process_group.

My training command is:

python -m train.train_diffusion --save_dir ./test_log/1 --data_root ./dataset/GQS883/ --batch_size 2 --dataset social --data_format face --layer 8 --heads 8 --timestep_respacing "" --max_seq_length 600

Do you have any idea? Many thanks!