Interactive access to a compute node¶
Artemis has two nodes dedicated to interactive access. Interactive sessions can be used for many reasons, including compiling code that requires more memory than is available on a login node, opening programs with graphical user interfaces, or testing code interactively on the command line.
Interactive session are requested using the
qsub -I command:
qsub -I -P PANDORA
remembering to replace
PANDORA with your abbreviated project name, as specified in your
RDMP. This command, by default, requests one core
and 4 GB of memory. You can request more resources using the
-l flag. For example:
qsub -I -P PANDORA -l select=1:ncpus=4:mem=16GB,walltime=4:00:00
You can use up to 4 cores interactively, and request up to 4 hours of walltime.
After your job starts, your terminal session will change from being on a login node to one of the interactive nodes (either hpc055 or hpc056).
[abcd1234@login2 ~]$ qsub -I -P PANDORA qsub: waiting for job 1234567.pbsserver to start qsub: job 1234567.pbsserver ready [abcd1234@hpc055 ~]$
To end your interactive session, type
exit. If successfully terminated,
you should see a message saying your job ended and you will be returned
to a login node:
[abcd1234@hpc055 ~]$ exit logout qsub: job 1234567.pbsserver completed [abcd1234@login2 ~]$
Opening GUI windows in an interactive session¶
If you logged into Artemis with a connection to an X server, as described in the opening GUI windows using X11 Forwarding section, you can open up programs with graphical user interfaces in the interactive session. To start an interactive session that can open GUI programs, use the following qsub command:
qsub -I -X -P PANDORA
you can change the resource request using the
-l flag, as described
in the previous section.
To open, for example, the Matlab GUI in an interactive session, simply load the Matlab module, then run Matlab:
[abcd1234@hpc055 ~]$ module load matlab/R2017a [abcd1234@hpc055 ~]$ matlab &
If successful, your Matlab GUI session will start. Note it may take a minute for the GUI to load, and that the GUI sessions aren’t as responsive as they are when run natively on your desktop computer.
Optimising the responsiveness of GUI windows¶
The responsiveness of GUI windows running on Artemis heavily depends on the speed of your local internet connection. The faster your local internet connection, the better your experience will be.
If you are on a slower internet connection, you can enable data compression to help speed up the GUI responsiveness.
Putty on Windows¶
Enable compression by ticking the “Enable Compression” check box in the Connection -> SSH option menu:
Starnet X-Win on Windows¶
Enable compression by navigating to your Artemis connection, selecting it, then clicking “Edit” in the menu options on the right. Then select the “Advanced” tab of the Edit Connection window, then tick the “Use Compression” check box:
MacOS and Linux¶
In the terminal app of MacOS, you can enable compression using the
to your SSH command:
ssh -YC firstname.lastname@example.org