Why is this increasing memory consumption on every iteration?

[Geancarlo Rocha]

On Sunday, 16 June 2013 at 18:02:26 UTC, Timon Gehr wrote:
> On 06/16/2013 07:20 PM, Geancarlo Rocha wrote:
>> On Sunday, 16 June 2013 at 02:12:02 UTC, Geancarlo Rocha wrote:
>>> I expected the memory to ramp up in the first couple 
>>> iterations and
>>> eventually reach a stable point, but for some reason, windows 
>>> task
>>> manager shows it increases on every iteration. Compiling with 
>>> -m64
>>> doesn't seem to change this issue.
>>>
>>> http://pastebin.com/G5JXR9AA
>>
>> I think it is safe to assume
>
> This way of reasoning is flawed.

Agreed, but hey...it caught someone's attention. Mission 
accomplished :)

>
>> the current GC is unreliable, booo!
>
> No it is not. You are not even allocating GC-controlled memory 
> during the loop.
>
> This is a std.container.BinaryHeap issue. It never shrinks the 
> underlying container.
>
> http://d.puremagic.com/issues/

If that is the case, I don't think that's something a beginner 
would figure out unless he went to look the source code.
Coming from C#, even the idea that you have to pass a "store" to 
the BinaryHeap is weird to me. I also don't understand this:

void toy()
{
     Array!(int) store;
     auto minheap = new BinaryHeap!(Array!(int), "a > b")(store);
     auto rng = new Random(unpredictableSeed);

     assert( store.length == 0 );
     writeln("inserting...");

     for( uint i = 0 ; i < 100_000 ; i++)
     {
         minheap.insert(1);
         assert( store.length == 0 );
     }
     writeln("done.");
     assert( store.length == 0 );

     writeln("removing");
     while(!minheap.empty)
     {
         minheap.removeFront();
         assert( store.length == 0 );
     }
     writeln("done.");
     assert( store.length == 0 );
}

I thought the BinaryHeap would modify store's buffer AND it's 
properties, but it doesn't seem to be the case. How is store 
being used? Again this is the sort of thing that makes a 
beginner's learning curve steeper.


Thanks for your attention