Re: gplt_x11 ignores SIGINT and SIGTSTP. Why?

[Ethan A M. <me...@uw...>]

On Thursday, 1 September 2022 00:12:01 PDT Dima Kogan wrote:
> Hi.
> 
> I'm looking at patching gplt_x11.c to work better with existing X window
> IDs. This is coming along. In the process I'm discovering other things.
> One is that for some reason the gnuplot x11 backend is explicitly
> ignoring the SIGINT and SIGTSTP signals:

You ask "why"?

I do not recall, or never knew, those details.
But I would imagine that it ignores SIGTSTP because backgrounding
gnuplot_x11 would be a bad idea - it would stop responding to new
commands from the main gnuplot process.

It's been too many years since I was seriously using or looking at the 
x11 terminal driver.  I think the world has moved on from direct use
of Xlib to drive graphics output, in favor of higher level libraries.

You said you were looking at this in order to create a gnuplot widget
for FLTK?  I've not previously heard of FLTK, and the fltk.org web site
is not particularly informative.  It looks like it's left over from
twenty years ago.  Can you describe the functionality you need?

For example, do you need mousing support inside this widget?
If not, can you use one of the png terminals rather than x11?
The graphics would be better, particularly the text handling.

Or maybe you could use svg + domterm?
http://domterm.org/Features.html


	Ethan

> 
>   https://urldefense.com/v3/__https://github.com/gnuplot/gnuplot/blob/e9779f00507187653b8fb317f492833af5eaaa9a/src/gplt_x11.c*L5270__;Iw!!K-Hz7m0Vt54!nm8TuNQnOSs9oWJELaBt7rhGmG84fkSGIXqAfuInBOuZk6jnG84SldATh5Xd6jUvN2MWtynemioL8wudnMTwBw$  
> 
> This results in zombie gplt_x11 processes. During normal operation
> usually this doesn't happen, but I do periodically see gplt_x11 zombies.
> While testing my new patches, I see these all the time, however. Does
> anybody know why we're ignoring these signals? Version control says that
> we were doing this from day 0 more or less.
> 
> Removing those two signal() calls doesn't obviously break anything, and
> results in the zombie processes going away. Can/should we get rid of
> those?
> 
> Thanks
> 
> 
> _______________________________________________
> gnuplot-beta mailing list
> gnu...@li...
> Membership management via: https://urldefense.com/v3/__https://lists.sourceforge.net/lists/listinfo/gnuplot-beta__;!!K-Hz7m0Vt54!nm8TuNQnOSs9oWJELaBt7rhGmG84fkSGIXqAfuInBOuZk6jnG84SldATh5Xd6jUvN2MWtynemioL8wuvoGg3ZA$  
> 


-- 
Ethan A Merritt
Biomolecular Structure Center,  K-428 Health Sciences Bldg
MS 357742,   University of Washington, Seattle 98195-7742