I really and a long time thought about a problem with a cronjob php skript. This script has to run long (in php terms, very long or lets say longer than one hour). I implemented a lot of verbose output and figured out that the script is using more and more memory. Thats why i implemented the using of "gc_enable()" and "gc_collect_cycles" without less luck. After a while i tackeld it down to my favorit used php orm mapper called propel. After having "propel" in my mind, the instance pooling comes in my mind and the final fix was reachable.
\Propel::disableInstancePooling();Add the code on top to your script and the memoryusage should not increase anymore (or you have another memory hole ;-)).