Strange problem with OpenGL and 1.2.0

I’ve had a strange problem with SDL’s opengl support and glx. Whenever
I use the gltest program in the SDL distribution with the -twice
option, it always locks up. CPU usage is pegged at 100%, and X
responds very slowly to events. It dies eventually (probably due to
mad ^C-ing), but is always reproducible. It sometime locks up if I run
a second gltest too soon after another normally. Adding a small delay
at the beginning of the loop on the first time around fixed the
problem. Is this an SDL problem? gears doesn’t exhibit this behavior.–
“This software comes with ABSOLUTELY NO WARRANTY. Even if it erases
your hard drive, too bad. Although we did fix that bug from the last
release.” --README from a long-ago release of DJGPP

I use the gltest program in the SDL distribution with the -twice
option, it always locks up. CPU usage is pegged at 100%, and X
responds very slowly to events. It dies eventually (probably due to
mad ^C-ing), but is always reproducible. It sometime locks up if I run
a second gltest too soon after another normally. Adding a small delay
at the beginning of the loop on the first time around fixed the
problem. Is this an SDL problem? gears doesn’t exhibit this behavior.

I haven’t gotten around to using SDL yet, but I’ve had an identical
situation whenever I remove the framerate limiting without removing the
XShmPutImage call.

X does not like it when you start plugging multiple PutImage’s per CRT
refresh at it…

Anything that forces a software implementation may or may not cause it to
block on crt refresh.