Deallocate array?

[Steven Schveighoffer]

On Tue, 07 May 2013 19:09:28 -0400, Matic Kukovec  
<matic.kukovec at pametnidom.si> wrote:

> Hi
>
> I'm running Windows Vista 64 with dmd 2.062.
>
> I have a simple program:
>
> import std.stdio, core.memory, std.cstream;
> void main()
> {
> 	string[] temp_array;
>
> 	for(int i=0;i<5000000;i++)
> 	{


> 		++temp_array.length;
> 		temp_array[temp_array.length - 1] = "aaaaaaaaaaaaaaaaaaaaa";

This is very inefficient, use temp_array ~= "aaaaaaaaaaaaaaaaaaaaa";

> 	}
> 	
> 	temp_array = null;
>
> 	GC.collect();
>          writeln("end");	
> 	din.getc();
> }
>
> When the program waits at "din.getc();", memory usage in the Task  
> Manager is 150MB.
>
> Why isn't the memory deallocating?

The GC does not return free memory to the OS, just to free memory  
pools/free-lists.  GC.minimize may or may not help.

But your code may not have freed that memory anyway.  It is not really  
possible to ensure that temp_array isn't referred to.  For example, the  
compiler could keep temp_array in a register.


> P.S.;
> I tried temp_array.clear() and destroy(temp_array), but nothing changed.

Neither of these will deallocate memory.  All are equivalent to setting  
temp_array = null.

If you want to ensure deallocation, you need to free it using  
GC.free(temp_array.ptr).  A very dangerous operation, use with caution,  
make sure there are no other references to that data.

-Steve