[vlc-devel] [Issue N176472] QCleanlooksStylePrivate::lookupIconTheme is broken

[Rafaël Carré]

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qt-bugs at trolltech.com a écrit :
> Hi Rafaël,
> 
> 
> On Wednesday, 29. Aug 2007 22:43 Rafaël Carré wrote:
>> qt-bugs at trolltech.com a écrit :
>>> Hi Rafaël ,
>>>
>>> Are you able to send us a stack trace at the point where you
>>> application locks/hangs?
>> i give you a strace log:
>> http://people.videolan.org/~funman/trolltech/strace.log
>>
>> there is 2 select() call that give a Timeout (search for "Timeout" in
>> the log, they're espaced of 6 lines).
>>
>> the first timeout almost immediately, and the second is the one that
>> makes the application hang. you'll also note they're 10-20 lines after
>> clone() calls (used to exec gconftool-2)
> 
> Thank you for providing me all these details, certainly very helpful.
> Are you able to run the following command from your shell?;
> 
> gconftool-2 --get /desktop/gnome/interface/icon_theme
> 
> Does it give any results. Qt uses gconftool to pick up the icon themes
> and we do that in a QProcess in a thread and if gconftool does not
> repsond back then it will timeout and the process will probably die.

% time gconftool-2 --get /desktop/gnome/interface/icon_theme
Human
gconftool-2 --get /desktop/gnome/interface/icon_theme  0,01s user 0,00s
system 76% cpu 0,016 total


sorry for not being explicit, there is no problem using gconftool-2, I
think the problem is that the QProcess terminates too quickly, and
because of that there is a timeout in QT code.

as you can see, gconftool-2 works well and outputs the desired
information very quickly.

> 
> I have reported this issue to the developers. This doesn't seem to a
> known problem and doesn't seem to be reproducible here.
> However, they will investigate further on this problem.
> 

did you try the little vlc build i made for you ? maybe you're not
allowed to execute untrusted code, i would understand of course.

i suppose it happens with vlc and not with a simple sample because vlc
adds an overhead, and delays qt4 execution, i suppose the bug is a race
condition.

i CC'ed our conversation to the VLC developers mailing list as they are
too intersted in this issue.

>>> Can you reproduce the problem with a small example, can
>>> you please send us such example?
>> Unfortunately, i've been unable to narrow it to a small example :(
>> Here is the diff i applied to the trunk version of vlc (subversion
>> repository): http://people.videolan.org/~funman/trolltech/qt4.diff
>>
>>> Which Desktop Manager are you using, Gnome?
>> Yes, gnome 2.19.91
> 
> This release is not stable and therefore not supported by Qt. Basically,
> it is not guaranteed that it will work. Have you tried a stable Gnome
> release, like 2.18 or older? Do you see any problems on other Desktop
> Managers, like KDE, BlackBox, XFCE?

I see the same problem using gnome 2.18, and Xfce 4.4.0.

Note the bug is specific to cleanlooks style, and this style is mostly
used with a gnome desktop, so the utilisation of a gnome-specific tool
to get icon theme info.
More over, the running desktop will not influence the invocation of
gconftool-2

> 
>>> Unfortunately, I am not able to reproduce the problem here when I
>>> use the Cleanlooks style after I set it up in the qtconfig tool. I
>>> would also recommend to get the latest Qt4.3.2 snapshot or the
>>> latest Qt 4.3.1 stable release and try to compile/install it
>>> manually in your system to see whether that makes any difference at
>>> all.
>> Setting up .deb qt4 packages is a pain and very long :( so i won't do
>> it if not necessary.
>>
>> To see if you can reproduce the problem without the pain of building
>> vlc, i uploaded a minimal package on:
>> http://people.videolan.org/~funman/trolltech/vlc.tar.gz
>>
>> run as:
>> LD_PRELOAD=lib/libvlc.so ./bin/vlc --plugin-path lib -I qt4
>>
>> thanks for your reply, let me know if that helps you to reproduce the
>> problem.
> 
> I will try to reproduce the problem here as well on my machine. However,
> as I mentioned previously the Gnome version you are using is not a
> stable one and therefore it is not supported since it could a problem
> on Gnome's side.

seeing that gconftool-2 works perfectly i suspect it's not the case :/

> 
> Kind regards,
> Petref
> 
> --
> Petref Saraci
> Support Engineer
> Trolltech ASA, Oslo - http://www.trolltech.com
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> 


- --
Rafaël Carré
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