Does the partial variables are copied when the partial function is called by multiprocessing?

I partialed my function

f = functools.partial(f, y=a)

with an object

a = SomeClass()

And the the function is called by

with multiproccessing.pool(4) as p:
    p.map(f, list_of_x)

I'm wondering does the a is copied in each process. Or the each process just refer to the same a?

Thanks!