bug#23875: 25.0.95; Emacs crashes when closing a frame on OSX

[Ivan Cibrario Bertolotti <ivan.cibrario@polito.it>]

> On 11 Sep 2016, at 20:18, Alan Third <alan@idiocy.org> wrote:
> 
> Ivan Cibrario Bertolotti <ivan.cibrario@polito.it> writes:
> 
>> unfortunately, no. I am still using Emacs with NSTRACE_ENABLED and
>> NSZombiesEnabled=YES, plus some extra debugging printouts of my own,
>> related to allocation and deallocation of EmacsImages. However, I
>> cannot trigger the bug anymore. In my opinion, there are two possible
>> reasons for this:
>> 
>> - triggering the bug was related to “something special” I was doing
>>  with Emacs at that time (somewhat unlikely), or
>> 
>> - it is a timing-dependent bug and the debugging printouts steered
>>  Emacs away from it (perhaps more likely)
>> 
>> At this time I seldom see EmacsImage allocations/deallocations in the
>> Emacs trace if at all. It seems to me that most of them are allocated
>> before dumping (like fringe bitmaps in bimgs, ns_draw_fringe_bitmap,
>> nsterm.m) and never deallocated.
>> 
>> I would like to force Emacs to make heavier use of EmacsImages and
>> increase the probability of running into the bug again, but I don’t
>> know the code base well enough for that.
>> 
>> If you know of any way of attaining that, please let me know and I
>> will give it a try.
> 
> I'm afraid I don't know any way of doing that. I guess you could just
> try loading and deleting images repeatedly:
> 
> (dotimes (i 10)
>  (let ((image (find-image '((:type xpm :file "delete.xpm")))))
>    (insert (propertize " " 'display `(,image (slice .0 .0 1.0 1.0)))))
>  (redisplay)
>  (delete-backward-char 1))
> 
> That should display a bin icon ten times quickly, but I don't know if
> it'll dealloc it each time or if it gets cached in some way.

Thank you, I tried something very similar in the past and it works perfectly.
In the trace I see a single instance of [EmacsImage initForXPMWithDepth:::],
so I guess the image gets cached.


> Since you're the only person to report this so far I'd be inclined to
> think that perhaps some part of your configuration is causing it. Would
> it be possible for you to turn off the debug output and try
> systematically disabling different parts of your configuration to see if
> the crashes go away? That could perhaps help us narrow down what code is
> causing the crash.

I agree, it makes a lot of sense, indeed.  I will definitely try to tweak
my configuration to the extent I can.

Concerning the way of using Emacs, may I ask if there is any “grey area”
in using Emacs in native full screen mode?

When I saw the bug, I was switching in and out of full screen mode quite
often.  One thing I noticed is that the bug appeared during or shortly
after a switch.

I don’t see how it can be related to EmacsImages, but it is
the most significant clue I can think of at this time.

Thank you so much again for your time and for the hints.  Sorry for not
being of much help.

Best regards,
Ivan