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

• is the tool we use for graphical applications
• in addition to VNC
• see Background information slides for more technical details

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

vncserver -geometry 1920x1080 -depth 24  :display-number

• 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

• 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

#!/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" 

#!/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" 

• 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

• 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

Live demonstration.