Where's my memory going?!

Hi all. I have a script that opens a socket, creates a persistent mysql connection, and loops to receive data. When the amount of specified data has been received, it calls a class which processes the data and inserts it into the database. Each iteration, I unset/destruct that class I call. However, the script keeps going up in memory and eventually runs out, causing a fatal error. Any thoughts on where to start to see where I'm losing my memory? Thanks in advance, ~Philip