Re: Memory Issue

[Allin Cottrell <cottrell wfu edu>]

On Mon, 18 Dec 2006, Preeti Joshi wrote:

> The above code creates a main window and from button1 click creates a
> message box . On closing this message box , memory allocated to message box
> should have been freed. However gnome-system-monitor shows the following
> stats:
> when main window is displayed: 3.5 MB
> when message box is also displayed: 3.9 MB
> message box closed: 3.9 MB
> main window closed through 'X' button: 3.9 MB

You don't have any call to gtk_main_quit() in your program, so 
closing the main window will not free the basic gtk/gnome memory 
allocation.

Besides that, gnome-system-monitor is not a leak checker.  If you 
saw the memory usage increasing every time you opened and closed 
the message box, that would indeed suggest a leak.  But what 
you're describing above is normal behaviour.  When a program calls 
free(), that action in principle makes the previously claimed 
dynamic memory available to the operating system.  But the 
operating system need not reclaim it.  The OS may leave the memory 
in question "lying around" for possible future use by the same 
program.  This increases efficiency.  For example, when you open 
the dialog a second time, the OS doesn't have to "find" the extra 
memory needed, it's still allocated to your program.

People sometimes seem to think that good memory management means 
having as much free RAM as possible available at any given 
moment.  But if you think about it, that makes no sense.  Memory 
is there to be used.  It's more efficient (if you're not about to 
run out of RAM) to keep previous memory allocations cached.

Allin Cottrell