Garbage Collection does not reduce current memory usage - in release mode. Why?

Question

I built a quick program that needed to loop through an enormous log file (a couple of million records) and find various bits and pieces from inside. Because the volume of da

Answer 1

It's normal for many memory allocators (with or w/o garbage collection) to "hoard" the memory they've freed, rather than give it back to the OS, because in many situations the memory just freed will be requested again and it's faster to keep it in the process rather than keep giving it back and asking the OS for it again and again (giving it back &c also requires extra effort due to page alignment issues and the like).

In a one-shot app, as you mention, that's not a problem. When I have a long-running app that has what I know will be a transient requirement for a lot of memory, one approach I use is to spawn a sub-process to perform the memory-hungry stuff, since when that process ends the OS will claw back the memory. It's easier on Unix systems (just fork) but not too bad on Windows, either, when warranted.