When does the heap memory actually get released?

Question

I'm allocating memory using new as and when I receive data in one of my methods and in the destructor, I'm releasing all the allocated memory using delete.

However, after releasing the memory, from the task manager, when I look at mem usage under the process tab, the memory usage still remains the same. It doesn't give an impression that the memory is being released.

So, when does the memory actually get released? And what is the best way to find out the actual memory being used by a process.

Thanks

Ben, I was using VC++ based code. Not sure, if Unix behaves differently. Thus, to make things clear, I added the tag MFC. — nsivakr, Jan 26 '12 at 20:31
Removed MFC tag. Left C++ and Windows even though this issue is pretty common to most programming languages on most OSes. — André Caron, Jan 26 '12 at 20:36
There's a nice answer here: http://stackoverflow.com/a/6494048/292432 — arx, Jan 26 '12 at 21:11

smparkes · Accepted Answer · 2012-01-26T20:44:03.973

2

In most cases, it's never given back to the OS while the app is running. Afterwards, of course, all resources are recovered by the OS.

[Edited after the comments rightly pointed out that 'never' is a long time ...]

edited Jan 26 '12 at 20:44

answered Jan 26 '12 at 20:20

smparkes

13,807
4
36
61

2

"at application exit" seems different from "never" – Ben Voigt Jan 26 '12 at 20:21
It is given back when the process exists at least, so I wouldn't call it never – Grizzly Jan 26 '12 at 20:23

score 0 · Answer 2 · answered Jan 26 '12 at 20:50

The OS allocates a default heap to your application. This heap is allocated during the initialization of your process. Thus, your new's and delete's won't affect the bar you see in the task manager.

However, if you try to initialize a big buffer and the allocated heap isn't enough, the OS will allocate more memory for your application - and this should be reflected in the task manager...

When does the heap memory actually get released?

2 Answers2

Linked