Interactive Jobs

Some of the applications available on BlueBEAR make use of a Graphical User Interface (GUI). Some of these are available in the BlueBEAR Portal and that is the preferred method of access for those applications that are available. Where an application is not available in the BlueBEAR Portal you can use an interactive job, with X forwarding enabled in your ssh session, to pass the GUI back to your own computer.

Using an Interactive Job

To start an interactive job, use the following commands:

module load slurm-interactive
fisbatch_screen --nodes 1-1 --ntasks 2 --time 1:0:0

You can send the same arguments to fisbatch_screen as you would put in a job script submitted using sbatch. I.e. to specify a QoS or project. The same limits on resources, such as wall time or number of cores requested, apply to interactive jobs. The example above asks for two cores, on one node, for one hour.

You will then see output similar to:

[info] Waiting for JOBID 3345516 to start
[info] Job 3345516 is running
[info] Job is running on bber0501u32b
[info] Connecting to head node (bber0501u32b)

Once the interactive job has started then you will be connected to the node the job is running on and you will be able to run your job commands here. So, to start MATLAB:

module load MATLAB/2018b

When you disconnect from the job, by exiting the terminal, then the job will automatically be cancelled. If you use an interactive job then it is your responsibility to make sure that you make good use of the resources. Please don’t leave the job idle, and remember to disconnect as soon as you’ve finished your work.

The fisbatch_screen command starts a screen session on node. There is an equivalent fisbatch_tmux command that uses tmux on the node. If you start a screen (or tmux) session on the login node and you wish to run an interactive job inside, then you should avoid nesting screen (or tmux) sessions by using the alternative with fisbatch_tmux (or fisbatch_screen) instead.

If you have connected to the login node with X forwarding then the graphical X connection will automatically be forwarded from the interactive job. See here for details how to do that on a Windows machine. Linux or Mac uses should use the -X ssh flag when logging in.


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