About VNC session

Get Help
1

Hello,

I have a problem where VNC session launches only after I do ssh to slurm compute node manually or if I do pre-login in slurm compute node (GUI) already phyisally in the server room. I am using mate desktop session in slurm compute node with ubuntu 24.04. I tried with a lot of options with batch job script to automate the launch of the vnc session but nothing works. As I am struggling more than a month with this, would be greatful I am if someone help me with this.

Thanks in advance!

2

Hello,
Is there anyone to help me with this?

3

Hi sorry for the delay. IIRC this has something to do with systemd’s loginctl enable-linger functionality. Searching for linger on this site seems to confirm this as well as a google search of “slurm vnc launches only after ssh login”

Something like this in prologue

loginctl enable-linger $ SLURM_JOB_USER

With something like this in the epilogue

loginctl disable-linger $SLURM_JOB_USER

4

Hi @jeff.ohrstrom,

Many thanks for your kind repsonse! I jus had a look at linger and got to understand how it works with vnc. But there’s another problem which I didn’t added in above details. Even thogh I enbale loginctl enable-linger for a specific user like below (an example);

$ loginctl enable-linger harjad

But then inside the vnc session, the web browser (Firefox, Chromium & Steam) is not working. Is this something related to desktop session or with remote enable loginctl? Cause thes ework well when I already login into the mate desktop (GUI) physically on a server. Do you have any suggestion or recommendaiton for this? This would be very helpful to go forward with my work as I was hanged up with this as well.

Thanks in advance!

5

I’m not 100% sure, but I’d suggest you start them from the command line to see the stdout output to see what the error could be.

6

Thanks again @jeff.ohrstrom

I already tried running firefox from Mate terminal where it throws the same error as below;


failed to load module "appmenu-gtk-module" No protocol specified Error: cannot open display: :4

But gtk moule already exists and the display is also open at :4 I don understand why this throws same error again and again. But this error doesn’t appear and also it works fine when I already login pysically in GUI node (slurm compute node). I tried my best to resolve this error but nothing works out. If you have any suggestion then please let me know!

Thanks again!

7

I’m not sure what could be the issue. Can you share the output.log and/or vnc.log from the job? That may give us some insight.

8

Thanks again @jeff.ohrstrom
I have enclosed the vnc and output logs here as txt files here. I don know whether is this a correct way to share the files or not. if not, please let me know the exact format which you feel comfortable. Your inputs are indedd;

Output_log.txt (23.1 KB)

VNC_log.txt (9.0 KB).

Thanks again!