what is the best qr package

what is the best qr package -- https://mail.python.org/mailman/listinfo/python-list

in multiprocessing pool map how to stop one process from executing ahead

I am excecting custom commands like shell on multiple linux hosts. and if in one host one of the commands fail. I want that process not to proceed. If the remote command throws an error i am logging it .. but the process goes to next command . but if i terminate the command, the process will t