Re: memory leak - cairo/x11 backend

[Riccardo Mottola]

Hi,

Thanks for taking a look at it.

Fred Kiefer wrote:
> I am able to reproduce this behaviour, but I am unsure about what it
> means. I did an in depth inspection with the memory panel of GNUstep,
> but this didn't show up a specific issue. (BTW the memory panel is hard
> to use with Laterna Magica. The AppController registers itself for the
> notification NSTableViewSelectionDidChangeNotification and as the
> fileListView is still null at the point in time where this happens it
> will get called even from the memory panel. The same is true for the
> other notification. You should move these calls into the awakeFromNib
> method)
Fine, I just moved those calls as you suggested.

I pointed out to two memory leaks: not only the Xorg doesn't get back to 
its original memory usage, but also LaternaMagica itself: in the example 
I went from X: 108 LM: 58, to X: 142 LM: 91. That is about a 35MB 
increase for the server, but also a 33MB increase of LM! Thus I see a 
problem on both sides, let's analyze LM, perhaps the problem is there 
and now the Xorg problem is a reflection of that.

You didn't find anything obvious, I too tried the memory panel without 
success. At start, I see no NSImageViews! why?

Clicking on an item yields
2013-12-22 18:47:19.268 LaternaMagica[14382] Problem posting 
notification: <NSException: 0x8127f00> NAME:NSRangeException 
REASON:Index 11 is out of range 0 (in
'objectAtIndex:') INFO:{Array = (); Count = 0; Index = 11; }

Anyway, at start I see:
NSBitmapImageRep: 12
NSImageView: ?
NSImage: ?

I load an image, while displaying it:
NSBitmapImageRep: 34
NSImageView: 1
NSImage: 193

I remove the image (do not "delete" it while testing :) )
NSBitmapImageRep: 33
NSImageView: 1
NSImage: 192

I don't know the original state, but it went back of one, so Indeed 
something get released, but is it enough?
> There is a lot of other strange code in Laterna Magica, for example:
>
>    [view setImage: destImage];
>    [view setNeedsDisplay:YES];
>    [[view superview] setNeedsDisplay:YES];
>    [window displayIfNeeded];
>
> Here only the first line should be needed. Why is the rest there?
> But none of that looks like an obvious memory leak.
I will check that, it looks I desperately had some redraw problems. That 
code needs to work both inside a window and with a full-screen window. 
Perhaps it is not needed anymore, I will check on Mac and GNUstep. 
However, you say yourself that it shouldn't cause memory problems. At 
most, it is inefficient/inelegant.

> I also tried to see any specific memory leaks with valgrind, but here
> the normal GNUstep leaks overshadow the output.
Well, "normal leaks".....
> And I am still not completely convinced that there is a problem. When I
> keep on loading and removing images the size of the XOrg process keeps
> returning to the same value it had before. Not to the initial one, but
> it does not keep on growing endlessly. It is more like the biggest image
> ever loaded in Laterna Magica determines the additional resource usage
> of the X process.
>
> Fred

Riccardo