How to stop server socket?

I meet this:

[W socket.cpp:401] [c10d] The server socket has failed to bind to [::]:29500 (errno: 98 - Address already in use).
[W socket.cpp:401] [c10d] The server socket has failed to bind to 0.0.0.0:29500 (errno: 98 - Address already in use).
[E socket.cpp:435] [c10d] The server socket has failed to listen on any local network address

I tried this:

ps -fA | grep python
And then kill -9 the pid

But next time I still meet the same error!
Could anyone kindly suggest me something? Thank you!!!

I think it’s unrelated to pytorch itself and there are a lot of options that people suggest on the SO: c - Bind failed: Address already in use - Stack Overflow