X11 forwarding batch interactive jobs

Introduction

In some cases it is useful to run a compute- or memory-intensive program with a graphical user interface (GUI). Such computations should not be run on a login node but on a compute node through the batch system. You can use batch interactive jobs with X11 forwarding.

Setting up X11 forwarding

For X11 forwarding batch jobs to work, you must first setup X11 forwarding from the Euler cluster to your workstation over SSH.

Now you need to setup X11 forwarding over SSH within Euler. Log in to Euler and run

/cluster/apps/local/setup_ssh.sh

These steps need to be done just once, not for every use.

Submitting X11 forwarding batch interactive jobs

Let's say you want to run xterm as an X11 forwarding batch interactive job. Connect to Euler with X11 forwarding enabled and run the command

[leonhard@euler02 ~]$ bsub -XF -R "rusage[mem=3000]" -Is xterm
Generic job.
Job <37994100> is submitted to queue <normal.4h>.
<<ssh X11 forwarding job>>
<<Waiting for dispatch ...>>

You now need to wait for the job to be dispatched (i.e., to start running). You will see something similar to

<<Starting on e2262>>

in your terminal and then the xterm window will show up on your desktop.

Such interactive jobs are currently restricted to at most 24 cores and 24 hours of runtime.

If you will work interactively or your job does not need to use the CPU constantly, then an additional option is to request the “-R light” resource:

[leonhard@euler02 ~]$ bsub -R light -XF -R "rusage[mem=3000]" -Is xterm

In exchange for (generally) a shorter waiting time and longer allowed runtimes, your job will not get dedicated access to a core. In addition you can currently use at most four cores this way.

Troubleshooting X11 forwarding batch interactive jobs

If the batch system detects that your connection to Euler does not support X11 forwarding, then it will reject your job submission:

[leonhard@euler02 ~]$ bsub -XF -R "rusage[mem=3000]" -Is xterm
Error: X11 connection is not set up.
Request aborted by esub. Job not submitted.
[leonhard@euler02 ~]$

Check your settings for SSH and X11 forwarding.