Hi guys, Thank you so much for the support on here. I don’t know parallel or distributed computing so please excuse me if my question is naive.
I will use HPC(high performance computer) for my research and I don’t know about parallel or distributed computing. I really don’t understand the  DistributedDataParallel()  in pytorch. Especially  init_process_group() . What is the meaning of initializing processes group? and what is

init_method : URL specifying how to initialize the package.

for example (I found those in the documentation):
'tcp://10.1.1.20:23456' or 'file:///mnt/nfs/sharedfile'
What are those URLs?
What is the Rank of the current process?
Is  world_size  the number of GPUs?
It would be really appreciated if someone explained to me What is and How to use  DistributedDataParallel()  and  init_process_group() in a simple way  because I don’t know parallel or distributed computing.
I will use things like Slurm(sbatch) in the HPC.