RE: [Mesa3d-users] Mesa-6.0.1 and multi-threaded X11 apps

[Rocky R. <rh...@sg...>]

Thanks Brian.  I probably won't have time to fool around with this for a day
or two, but I'll try running the glthreads test just to make sure it works
here for me and making the change you mention to xm_api.c as well.  I've
been looking around for a call to XInitThreads in this code, but haven't
figured it out yet.  I'll look some more for that when I get a chance, too.

	Rocky

> -----Original Message-----
> From: Brian Paul [mailto:bri...@tu...]
> Sent: Tuesday, April 06, 2004 1:35 PM
> To: Rocky Rhodes
> Cc: 'mes...@li...'
> Subject: Re: [Mesa3d-users] Mesa-6.0.1 and multi-threaded X11 apps
> 
> 
> Rocky Rhodes wrote:
> > I've got a (large) multi-threaded C++ application I'm 
> trying to run on an
> > SGI Altix machine (IA64 Linux) with no graphics card.  The 
> code uses OpenGL
> > and glut and reputedly runs fine on many hardware/software 
> configurations.
> > When I run it on the Altix with a Mesa-6.0.1 gl I see a 
> number of issues
> > with Xlib.  If I just run the program as is, the 
> application freezes after
> > painting a GUI window, never painting the main OpenGL 
> window.  If I run the
> > app with a "-sync" flag for glut to run with synchronous X protocol
> > transmissions, the application runs better, but still gives 
> me Xlib errors
> > occasionally, particularly "Xlib: unexpected async reply (sequence
> > 0xblahblah)!".
> > 
> > Are there any problems using Mesa and glut with 
> multi-threaded apps?  The
> > X11R6 info seems to blame these "unexpected async reply" errors on
> > multi-threaded applications improperly using Xlib concurrently.
> > XInitThreads, XLockDisplay, XUnlockDisplay?
> > 
> > Thanks for any help you may be able to provide.
> > 
> > 	Rocky
> 
> Hi Rocky,
> 
> Hard to say what the problem is off-hand.  The only threaded 
> test that I 
> regularly run is the progs/xdemos/glthreads.c test from the 
> Mesa distro. 
>   It seems fine here.
> 
> Mesa's Xlib device driver is meant to be thread-safe, but 
> there could be 
> a bug somewhere.  Actually, I'm looking at the XMesaSwapBuffers() 
> function in src/mesa/drivers/x11/xm_api.c and see that the calls to 
> _glthread_LOCK/UNLOCK_MUTEX() are commented out (don't know 
> why).  You 
> might try re-enabling them to see what happens.
> 
> Does your application call XInitThreads() like the 
> glthreads.c program?
> 
> I don't know if GLUT is meant to be thread-safe either.
> 
> -Brian
>