[Twisted-Python] Python chess game server issue, data is not received the blocking of ambigious process in the same virtual host.

[8]

A python process listen on port 4001, and there is clients connected to it and play some chess game. but strangely, One more than two days later, there may be one or two more other process listen on the same port 4001 which block the data which should send to my python server.
I use the "sudo netstat -antup" intented to find the process ID, but that newly created process listening on port 4001 has no pid or pname.
And when I try to kill the initial python server process listening on port 4001 using command kill pid, after exected the kill command, I use netstat -antup again, suprisingly, I found that process which should be killed are still alive.
Then I use command kill -9 pid to kill it, then execute netstat - antup commnd, all the process listening on port 4001 disappeared.

Would u please kindly give me any answer?

I use the TWISTD to start my application. the outline for them is below:
$TWISTD ......
from twisted.application import service, internet
application = service.Application("myserver")
Thanks,
Mark
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