how to avoid memory leaking

[Benjamin Thaut]

On Sunday, 12 May 2013 at 11:27:15 UTC, maarten van damme wrote:
> I tried using gc.malloc and gc.free but got an 
> invalidmemoryoperation
> exception when doing gc.free(data.ptr);
> Simply using gc.malloc like you proposed, the memory keeps 
> growing. Is this
> a bug in the d garbage collector?
>
> What's really strange though, is that the destructor of 
> trueimagecolor (the
> class allocating the buffer) is getting called everytime...
> Does this mean that a destructor getting called still is no 
> garantee that
> all data is getting free'd?
>
>

Calling GC.free should not be neccessary as the data will still 
be collected.  The destructor of TrueImageColor beeing called 
does not mean the Array with the Image Data gets collected. Are 
you Sure that TrueColorImage is the only class holding a 
reference to the data? Do you take a slice of the data somewhere?


>
> 2013/5/12 Benjamin Thaut <code at benjamin-thaut.de>
>
>> Am 11.05.2013 01:18, schrieb maarten van damme:
>>
>>  I'm trying to generate images and after displaying them I 
>> want to save
>>> them to a png file. I use parallelism to generate them 
>>> asynchronously
>>> with the gui-thread to avoid blocking (don't know if this is 
>>> really
>>> relevant).
>>>
>>> If I add a single line in the method where I generate the 
>>> image that
>>> creates a class which allocates a pretty big array, slowly 
>>> but surely
>>> the memory starts to rise until it ends in a spectacular out 
>>> of memory
>>> exception. I always thought the garbage collector would deal 
>>> with it.
>>>
>>> I tried reducing it but failed. Maybe I should let dustmite 
>>> bite in it a
>>> bit later.
>>> How can I manually fix this? Is this a known bug in the 
>>> garbage collector?
>>>
>>> btw, this code also caused segfaults on my  64 bit laptop on 
>>> linux.
>>> How can I avoid this?
>>>
>>> main class:
>>> https://dl.dropboxusercontent.**com/u/15024434/**
>>> picturegenerator/generalised.d<https://dl.dropboxusercontent.com/u/15024434/picturegenerator/generalised.d>
>>>
>>> zip file with everything ready to go to compile:
>>> https://dl.dropboxusercontent.**com/u/15024434/**picturegenerator/**
>>> picturegenerator.zip<https://dl.dropboxusercontent.com/u/15024434/picturegenerator/picturegenerator.zip>
>>>
>>
>> Try allocating the big array with:
>>
>> import core.memory;
>>
>> size_t imageSize = 1024*1024*3;
>> auto imageData[] = (cast(ubyte*)GC.malloc(**imageSize ,
>> GC.BlkAttr.NO_SCAN)[0..**imageSize];
>>
>> Which will result in the big memory block not beeing scanned 
>> by the GC
>> which should reduce the number of false positives during 
>> collection.
>>
>> If this doesn't work, use malloc / free of the c standard 
>> library to
>> allocate and free the image data.
>>
>> Kind Regards
>> Benjamin Thaut