intermittent freezes, glPushAttrib

[James W. Walker]

On certain machines running Windows, with Nvidia cards, our OpenGL code experienced intermittent freezes. That is, once in a while at irregular intervals, everything (including the mouse cursor) would freeze for maybe 3 to 8 seconds. We couldn't reproduce it on a PC with an ATI card, nor on a Mac with an Nvidia card.

The problematic area of the code looked like this:

glPushAttrib( GL_LINE_BIT );
glLineWidth( myWidth );
DrawSomeLines();
glPopAttrib();

After changing it to the following, the problem went away:

glLineWidth( myWidth );
DrawSomeLines();
glLineWidth( 1.0f );

And if I did this, the problem came back:

glPushAttrib( GL_LINE_BIT );
glPopAttrib();
 
glLineWidth( myWidth );
DrawSomeLines();
glLineWidth( 1.0f );

Any of this ring any bells?