Why does this launch an infinite loop of new processes?

[Andrew Berg]

I am trying to understand the multiprocessing module, and I tried some
simple code:

import multiprocessing
def f():
print('bla bla')
p = multiprocessing.Process(target=f)
p.start()
p.join()

And the result is a new process that spawns a new process that spawns a
new process ad infinitum until I log out and the OS forcefully
terminates all my user processes. I have no idea what is happening; I
expected it to just print the string and terminate.