I don't really know anything about Qt, but the "async reply"
looks like a thread saftey problem. If you don't have any interaction
with Xlib directly, then this sounds like a Qt bug or a bug in an
X library. There are three ways an app can have thread safe access
to X libraries:
1) Have every thread use a separate display connection. In this case
every thread has its own communication channel with the X-server.
2) Use one display connection but have the client (Qt in this case)
ensure exclusive access to the connection through thread mutexes.
3) Enable Xlib's own mutexes via XInitThreads().
If Qt was doing #1, there would never be a problem.
If Qt was doing #2 there would be no problem as long as they had all
their mutexes correctly in place - that's a lot of mutexes. If Qt was
doing #3 there would never be a problem unless there was a missing
mutex in one of the X libraries. I suggest that if this was the case
it would probably have to be a library for a newer extension, because
the core X libraries are as old as dirt and have very few if any of
these types of bugs.
On Wed, 18 May 2005, [ISO-8859-1] "Alexander Carôt" wrote:
> Hi Mark,
>
> thanks for the quick answer. What do you mean by "separate display
> connections" ? The case is this :
I mean a display connection returned by XOpenDisplay.
There is a man page for XInitThreads. I don't know how Qt
ensures thread saftey, but my guess is that this is a Qt
bug with their thread support or a user bug with not initializing
Qt thread support properly.
Mark.
>
> I have one Qt-GUI that responds to each click on any widget. Beside this an
> audio callback thread is running that as well accesses the same GUI via an
> pointer on the current application object.
>
> Since this is an audio transmitter/receiver the graphical functionality is
> not very exiting - no X-Render extension. Also I havn't called XInitThreads
> () either. Should I call it right away ?
>
> If you have further ideas please let me know. Otherwise I'll get back to you
> if I know more.
>
> Best
>
> -- A l e x
>
> >
> > Do the threads have separate display connections? If not,
> > was XInitThreads() called before opening the display connection?
> > It could be possible that there is a thread safety bug in one of
> > the X libraries, but it's unlikely to be a bug in old functionality.
> > Is this application/widget using something new like the X-Render
> > extension?
> >
> > Mark.
> >
> > On Tue, 17 May 2005, [ISO-8859-1] "Alexander Carôt" wrote:
> >
> > > Hi to all,
> > >
> > > I have a Qt-Application using a callback thread that updates two widgets
> > > each 10 ms. In general this works fine but sometimes ( i.e. each 10
> > minutes)
> > > I get a crash with this error message :
> > >
> > > Xlib: unexpected async reply (sequence 0x232df6)!
> > >
> > > Can anyone tell how to approach this error ?
> > >
> > > Thanks in advance
> > >
> > > -- A l e x
> > >
> > > --
> > > Dipl.-Ing. Alexander Carôt
> > > Email : Alexander@xxxxxxxx
> > > Tel.: +49 (0)177 5719797
> > >
> > > phd-student at www.isnm.de
> > >
> > > Weitersagen: GMX DSL-Flatrates mit Tempo-Garantie!
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> >
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>
> --
> Dipl.-Ing. Alexander Carôt
> Email : Alexander@xxxxxxxx
> Tel.: +49 (0)177 5719797
>
> phd-student at www.isnm.de
>
> Weitersagen: GMX DSL-Flatrates mit Tempo-Garantie!
> Ab 4,99 Euro/Monat: http://www.gmx.net/de/go/dsl
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