[Octave-bug-tracker] [bug #42665] Windows (Xming) gnuplot viewers crash, leaving defunct processes on host machine

[Colin Foster]

Follow-up Comment #2, bug #42665 (project octave):

"Thanks for your bug report. For clarity, is the bug that gnuplot figures are
"crashing" (disappearing?), or that Octave is crashing, or that zombie
processes are being left behind on your server when the clients are done with
their Octave session?"

My apologies: Zombie processes are being left behind on my server when the
clients are done with their Octave session.



"What do you mean by an "Octave server"? Is each client running its own
instance of Octave over an SSH session? If so, then when Octave exits the
gnuplot processes should be cleaned up."

Yes, each client is running octave over SSH through PuTTY, using X11
forwarding to xming.


"Or do you mean each client is somehow connecting to a single instance of
Octave that stays running in the background? "

No, each SSH instance starts its own Octave session.



Recreating the issue:
Start xming
ssh to the server, with X11 forwarding, from PuTTY
Create a plot using gnuplot:

figure
x=0:.01:2*pi
y=sin(x)
plot(x,y)

Check processes on server:
  ps aux | grep gnuplot
  253:user     24624  0.0  0.1 191732 12536 pts/19   S+   22:43   0:00
gnuplot
  254:user     24626  0.0  0.0  27560  1632 pts/19   S+   22:43   0:00
gnuplot_x11
Close PuTTY by clicking on the X in windows

Check processes on server:
  ps aux | grep gnuplot
  250:user     24624  0.0  0.0      0     0 ?        Z    22:43   0:00
[gnuplot] <defunct>



Looking at this log, it seems that two instances are being created, gnuplot
and gnuplot_x11. The latter gets terminated. The former gets abandoned.

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