I think you're misinformed.
Here are some more details if you're interested:
http://en.wikipedia.org/wiki/Garbage_collection_(computer_sc...
Here are some more details if you're interested:
http://en.wikipedia.org/wiki/Garbage_collection_(computer_sc...
Also, garbage collection does not "harvest for memory locations that need to be freed and frees them.". Garbage collection does not collect garbage, it collects used space.