bulk user creation

i have to populate a database wirth 9000 usernames with common password . how do i do it.

Using the same techniques and process that you might use for creating 1 user - or for creating 9000 objects of any type.

What is the source of these usernames? That’s going to affect exactly how you’d do this. If you’ve got them in some kind of text file, I’d probably write a custom management command to read each line of the file and create a User object for that user name.
See the set_password method for setting the password on a User object.