Get memory usage report from GC

[Rainer Schuetze via Digitalmars-d-learn]

On 20.02.2016 07:22, tcak wrote:
> On Saturday, 20 February 2016 at 05:55:26 UTC, Jon D wrote:
>> On Saturday, 20 February 2016 at 05:34:01 UTC, tcak wrote:
>>> On Saturday, 20 February 2016 at 05:33:00 UTC, tcak wrote:
>>>> Is there any way (I checked core.memory already) to collect report
>>>> about memory usage from garbage collector? So, I can see a list of
>>>> pointer and length information. Since getting this information would
>>>> require another memory area in heap, it could be like logging when
>>>> report is asked.
>>>>
>>>> My long running but idle program starts using 41.7% of memory
>>>> (that's close to 3GB), and it is not obvious whether the memory is
>>>> allocated by a single variable, or many variables.
>>>
>>> My mistake, it is close to 512MB.
>>
>> Doesn't sounds like precisely what you want, but there are summary
>> reports of GC activity available via the "--DRT-gcopt=profile:1"
>> command line option. More info at: http://dlang.org/spec/garbage.html
>>
>> --Jon
>
> I checked it out now. Yes, it is not that much useful unfortunately.
>
> The process is a daemon. stdin, stdout, and stderr are forwarded to
> /dev/null,
> thus, there is nothing like getting a text report at the end of process.
>
> I am still looking for a way to at least hook up to GC, so when it
> allocates,
> or deallocates, I could log it myself.

You can add path-to-druntime/src/gc/gc.d to your build command line and 
add option -debug=PRINTF_TO_FILE. This will redirect output to gcx.log.

If you add option -debug=PRINTF, it will print some API calls. You might 
have to check gc.d whether the ones that interest you are commented out, 
though.