[Zope-dev] Flush memory from product

Hello zopers, I'm writing a product with a relational database mapping. When I launch loading procedures, the product creates ~ 50000 instances. I regulary do a get_transaction().commit(), but memory still increase constantly (more than 300 megs for python processes) How can I flush memory ? Tested with : gnu/linux debian potato, zope 2.3.3 gnu/linux debian woody, zope 2.5.0