Why deleting large variables doesn't free up any memory?

[sdieselil]

Hi

I'm using Python 2.2.2 under FreeBSD. When I create a large variable
(using for example "a = range(1000000)") 'top' command indicates that
Python ate 12MB of swap space. But when I execute "del a" nothing
happens, it doesn't release these 12MB! Using "gc.collect()" also
doesn't help. What's the problem? What happened to Python's garbage
collector?