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===== Graphical Applications =====

Running graphical applications interactively

  * is an important feature on our clusters
  * is not a usual feature of HPC clusters
  * because it also makes things complicated
    * how/where to display the graphics
    * scheduling of interactive jobs


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===== Xpra =====

  * is the tool we use for graphical applications
  * in addition to VNC
  * see [[06_background_info.html#(3)|Background information]] slides for more technical details


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===== start VNC desktop =====

  * start VNC server (e.g. on login node 1):

<code>
vncserver -geometry 1920x1080 -depth 24  :display-number
</code>
  * use UID (user id) minus 30000 as display-number
  * MATE desktop (is a fork of Gnome 2) is preconfigured in ''%%~/.vnc/xstartup%%''
  * connect your VNC-viewer to address ''%%mul-hpc-81a.unileoben.ac.at:display-number%%''
    * or ''%%mul-hpc-81b%%'' for login node 2


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===== Xpra overview =====

  * Xpra server runs on same compute nodes as application
    * it is started together with application in job script
    * each application has a dedicated Xpra server
  * the display can be detached and reattached any time


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===== Job script =====

==== example for Abaqus CAE 2017 ====

<code>
#!/bin/bash
#SBATCH --partition E5-1650
#SBATCH --qos=E5-1650-inter
#SBATCH --nodes=1
#SBATCH --ntasks-per-node=1
#SBATCH --mem=15G
#SBATCH --job-name=abqcae

abq=/opt/sw/x86_64/generic/abaqus/Commands/abq2017

xpra start                 \
  --daemon=no              \
  --exit-with-children=yes \
  --start-child="$abq cae -mesa" 
</code>

----

===== Job script =====

==== example for Fluent 17.1 ====

<code>
#!/bin/bash
#SBATCH --partition E5-2690v4
#SBATCH --qos=E5-2690v4-inter
#SBATCH --nodes=1
#SBATCH --ntasks-per-node=14
#SBATCH --mem=30G
#SBATCH --job-name=fluent171

fluent=/opt/sw/x86_64/generic/ansys_inc/v171/fluent/bin/fluent

xpra start                 \
  --daemon=no              \
  --exit-with-children=yes \
  --start-child="$fluent 3ddp -t1" 

</code>

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===== attach display =====

  * to see the graphical output you must attach to the Xpra server
    * use ''%%sbatch+display%%'' to submit and display a job
    * use ''%%display JOBID%%'' to display job with given JOBID
    * use ''%%display-all%%'' to display graphical output of all your jobs


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===== detach display =====

  * the display can be detached and reattached any time
  * to detach the display:
    * use ''%%undisplay JOBID%%'' for one JOBID
    * use ''%%undisplay-all%%'' for all your jobs
    * or use symbols on the upper right side of MATE desktop


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===== attach/detach display =====

Live demonstration.


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