Memory problem with Python

[Squzer Crawler]

i am developing distributed environment in my college using Python. I
am using therads in client for downloading wepages. Even though i am
reusing the thread, memory usage get increased. I don know why.? I am
using BerkelyDB for URLQueue, BeautifulShop for Parsing the webpages.

Any idea of redusing the memory usage.. please tell me....

I want my program to run in bouded Memory.. Please..........