Re: XForms: Problem with Threads and ACE

Markus von der Heyde (
Tue, 24 Mar 1998 12:20:52 -0500

# To subscribers of the xforms list from Markus von der Heyde <> :

Hi Joerg,

there was a short discussion about a similar problem in the middle of
January. SPL answered at that time:

> X itself is not terribly thread friendly, though X11R6 purports to
> support threads in some limited fashion.

> There is some discussion of the thread compatibility in the O'Reilly
> X11R6 supplement manual. You might take a look there. Offhand, not
> having studied this subject in a lot of detail, I don't know how well
> this will work WRT XForms.

> The best counsel I can give is to develop your threaded application in
> such a way that only one thread attempts to communicate with X or
> XForms and the other threads make appropriate requests to the X thread
> for interaction.

I have done extensively development with pthreads and X before using
xforms, but I used Tcl/Tk. My experience, especially for Linux was,
that we had to compile X with the same pthread stuff to make it

An other point is the signal handling... You should not mix POSIX and
System V signal routines. Pthread is using POSIX signals. What's about
the xforms lib? I found only a call to signal(?). But which style is
used internally; is it a call for 4.3BSD (build on top of POSIX) or
System V ?

Have fun !

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