No ouput by running the pytorch DDP example

I am a freshman on using DDP, so I am trying to run an example supported by Pytorch. Its link is There are 4 GPUs on my machine. PyTorch version: ‘2.0.1+cu117’; OS: Ubuntu 20.04.4 LTS
When I run the code with the following command format python 10 5 > output.tx &, it will spend several hours without output, even without errors. I know it did run because it created a new file named “” It should finish in a minute and print out something like [GPU 0 ... [GPU 1 ... [GPU 2 ... [GPU 3 ...
Could someone help me?