Re: [HTCondor-users] Condor and Photoshop action

[Michael V Pelletier <Michael.V.Pelletier@xxxxxxxxxxxx>]

From: Gandor Florian swisstopo <Florian.Gandor@xxxxxxxxxxxx>
Date: 02/03/2016 09:04 AM

> It seems to me that Photoshop needs the GUI to
run actions and that 
> HTCondor canât run applications that need the GUI to workâ
> In advance, thanks for your answer,

This won't be applicable to your situation, unfortunately,
but it may give you an idea on how to figure out something that would work
on Windows.

On Linux, MATLAB plotting depends on the existence
of an X Windows display, and without it, it uses a crummy little 640x480
VGA canvas and so your plots come out looking like bedraggled refugees
from an 1980's Atari video game.

There's a tool called "Xvfb" (yum install
xorg-X11-server-Xvfb on Red Hat 6) which creates a virtual display in memory
which can be used in the same way as a physical display by software - you
just set the -display argument or the DISPLAY environment variable to point
to the proper number - it defaults to using display 99, so you'd just export
DISPLAY=:99.0 - and by setting this up as a beefy 1280x1024x32 display,
coupled with the -softwareopengl command line option, MATLAB is happy as
a clam and produces the high-quality plots you need using the virtual X
display, without the need for a physical GUI.

This utterly transformed the productivity of one of
our mod/sim teams, who had been stuck running MATLAB jobs on volunteer
users' machines by hand, since they were the only ones which had a usable
display.

The Xvfb is invoked when requested via the job's +WantXvfb
= True attribute, using a USER_JOB_WRAPPER. I attempted to do it using
a prepare-job hook, but all prepare-job processes are killed, including
a forked Xvfb daemon, when the hook ends and the job begins. The wrapper
also looks at +XvfbScreenSize and +XvfbPixDepths attributes for changes
to the default dimensions, and sets the job's DISPLAY environment variable
to the correct value based on what display number is chosen by the Xvfb
daemon.

(I'm hoping to be able to publish this code in the
coming months, I'll let everyone know if I get through the hurdles.)

I'm not sure if there's something comparable that
could be done with Windows, but good luck in any case!

        -Michael Pelletier.
_