Shopping cart logic ideal solution?

I am designing a shopping when this question struck me: If a shopper adds the max quantity of a certain item in my cart and doesn't commit the purchase, should other shoppers able to "snatch" it off her cart? What if the original shopper decides to make the purchase moments later just to find out that everything is gone in the cart but if the items are locked to the original shopper and he/she does not commit the items forever, no one else can buy them.