Re: [Caml-list] Crashing X.Org with lablgl

[Jacques Garrigue <garrigue@math.nagoya-u.ac.jp>]

From: David Thomas <david_hd@yahoo.com>
> Working on a 3d plotting program in ocaml, using
> lablgl.  I got it working on my laptop, which is
> running Debian 3.1, with XFree86.  All seemed to run
> fine.  
> 
> Moved it over to another box, it runs fine for about a
> minute before the X server segfaults.  Duplicated the
> result on three computers at work, all running X.Org
> under Debian. Works fine on another computer running
> XFree86.

You should at least say which front-end you use for lablGL (Tcl/Tk,
Glut or LablGTK). This may be relevant.

> 1) I'm sure that there *shouldn't* be any sequence of
> calls to lablgl that should outright crash the X
> server... does anyone know how true this proves in
> practice?

Well, if there is a bug in the X server, a program may trigger it.
Personally I've never seen that for lablGL though. And the reports
I've seen were about the program itself segfaulting, not the server.

> 2) Any thoughts as to how I can pinpoint the problem a
> bit better?

Sending me the complete source to try to reproduce the problem?

You could also look at the features you are using: does turning
double-buffering off change anything, are you using lots of display
lists...

> 3) Any suggestions for working around it?  Considering
> writing a simple library implementing the parts of
> lablgl that I need (which is relatively limited, as
> it's ultimately line-drawing), but that's not
> thrilling...

It might work. But would it not be simpler to write most of your display
code in C, and just the logic in ocaml. This way, if the same problem
pops up again you would have some C code to show the developpers.

Jacques Garrigue