Best properly way to destroy a 2 dimensional array?

[Steven Schveighoffer via Digitalmars-d-learn]

On 4/8/16 11:08 AM, Jonathan Villa wrote:
> On Thursday, 7 April 2016 at 16:13:59 UTC, Steven Schveighoffer wrote:
>> On 4/6/16 3:54 PM, Jonathan Villa wrote:
>>
>> You are likely running into the GC being conservative. You are also
>> possibly running into an issue where you are expecting the compiler to
>> do something with the stack where it may do something else. A classic
>> question that is asked on D forums all the time is why when you null
>> some variable and then call GC collect, the memory isn't collected.
>> The answer is because quite possibly the value is still in a register,
>> and the registers must be scanned too.
>>
>> As for conservatism, if you generate a 1-million element array of
>> pointers (each element has a pointer in it), then you have some random
>> stack variable that "happens" to point into that giant array (more
>> likely in 32-bit systems), then both the array, and all it's pointing
>> at gets saved.
>>
>
> Good, I compiled the program in 64 bit mode (-m64) and now it release
> memory normally like in Debian.

Definitely, 64-bit is less likely to randomly point at memory. This 
isn't 100% sure-fire way to fix the problem though.

>
> I would like to know where can I learn more about the 'register' or the
> GC for the D so I can avoid future issues.

Your best bet is to free the memory itself if it's possible.

import core.memory: GC;
GC.free(combs.ptr);

For more info on how GC works: dlang.org/spec/garbage.html

-Steve