GC: Memory keeps growing

[Rikki Cattermole via Digitalmars-d-learn]

On 16/04/2015 12:03 a.m., Chris wrote:
> On Wednesday, 15 April 2015 at 11:48:26 UTC, Rikki Cattermole wrote:
>> On 15/04/2015 11:44 p.m., Chris wrote:
>>> My garbage collected app starts with ~10 MB in memory, however with
>>> every execution of code it grows by at least 0.2 MB (or more depending
>>> on the input). Although I can see memory being freed (say it goes up to
>>> 32 MB and drops to 14 MB), it keeps on growing slowly but surely.
>>>
>>> I use structs for the most part [1] and reuse arrays at critical points,
>>> clearing them with destroy() after use. Maybe this is the problem? I
>>> dunno. I'd be grateful for any hints.
>>>
>>> [1] The few classes I use are either singletons or instantiated only
>>> once and cached when the programs starts.
>>
>> Sounds like you are doing a LOT of allocations. Try with -vgc during
>> compilation to find out where you are allocating.
>
> Just did that, for the most part it's:
>
> - indexing an associative array may cause GC allocation
> - operator ~= may cause GC allocation
> - operator ~ may cause GC allocation
>
> Whereas "'new' causes GC allocation" is rare and applies only to classes
> that are instantiated only once. I use appender a lot, too.
>
> There might be some low-hanging fruit there. However, before I change
> anything, maybe you guys have some suggestions.

The only real suggestions here are -vgc and @nogc.
Something must, must be holding on to references.