Manually freeze X server

Question

Is it possible to manually freeze the Xorg display server on Linux? If so, how?

This would be for testing purposes. I think that there are a lot of situations this could be useful for, but I currently want to use this to test Linux's ability to recover with SysRq keys from X freezing.

Answer 1

You might send a SIGSTOP signal to Xorg with

 sudo pkill -STOP Xorg

and later send it a SIGCONT signal.