[slurm-users] Srun not setting DISPLAY with --x11 for one account

[William Brown]

There are differences for X11 between Slurm versions so it may help to know
which version you have.

I tried some of your commands on our slurm 19.05.3-2 cluster, and
interestingly on the session on the compute node I don't see the cookie for
the login node:  This was with MobaXterm:

[user at prdubrvm005 ~]$ xauth list
prdubrvm005.research.rcsi.com/unix:10  MIT-MAGIC-COOKIE-1
 2efc5dd851736e3848193f65d038eca8
[user at prdubrvm005 ~]$ srun --pty  --x11  --preserve-env /bin/bash
[user at prdubrhpc1-02 ~]$ xauth list
prdubrhpc1-02.research.rcsi.com/unix:95  MIT-MAGIC-COOKIE-1
 2efc5dd851736e3848193f65d038eca8
[user at prdubrhpc1-02 ~]$ echo $DISPLAY
localhost:95.0

Any per-user problem would make me suspect the user having a different
shell, or something in their login script.  Can you make their .bashrc and
.bash_profile just exit?  Or look for hidden configuration files for
<something> in their home directory?

William



On Fri, 24 Jan 2020 at 16:05, Simon Andrews <simon.andrews at babraham.ac.uk>
wrote:

> I have a weird problem which I can’t get to the bottom of.
>
>
>
> We have a cluster which allows users to start interactive sessions which
> forward any X11 sessions they generated on the head node.  This generally
> works fine, but on the account of one user it doesn’t work.  The X11
> connection to the head node is fine, but it won’t transfer to the compute
> node.
>
>
>
> The symptoms are shown below:
>
>
>
> A good user gets this:
>
>
>
> [good at headnode ~]$ xauth list
>
> headnode.babraham.ac.uk/unix:12  MIT-MAGIC-COOKIE-1
> f04a2bf9a921a3357e44373655add14a
>
>
>
> [good at headnode ~]$ echo $DISPLAY
>
> localhost:12.0
>
>
>
> [good at headnode ~]$ srun --pty -p interactive --x11  --preserve-env
> /bin/bash
>
>
>
> [good at compute ~]$ xauth list
>
> headnode.babraham.ac.uk/unix:12  MIT-MAGIC-COOKIE-1
> f04a2bf9a921a3357e44373655add14a
>
> compute/unix:25  MIT-MAGIC-COOKIE-1  f04a2bf9a921a3357e44373655add14a
>
>
>
> [good at compute ~]$ echo $DISPLAY
>
> localhost:25.0
>
>
>
> So the cookie is copied from the head node and forwarded and the DISPLAY
> variable is updated.
>
>
>
> The bad user gets this:
>
>
>
> [bad at headnode ~]$ xauth list
>
> headnode.babraham.ac.uk/unix:10  MIT-MAGIC-COOKIE-1
> c39a493a37132d308b37469d363d8692
>
>
>
> [bad at headnode ~]$ echo $DISPLAY
>
> localhost:10.0
>
>
>
> [bad at headnode ~]$ srun --pty -p interactive --x11  --preserve-env
> /bin/bash
>
>
>
> [bad at compute ~]$ xauth list
>
> headnode.babraham.ac.uk/unix:10  MIT-MAGIC-COOKIE-1
> c39a493a37132d308b37469d363d8692
>
>
>
> [bad at compute ~]$ echo $DISPLAY
>
> localhost:10.0
>
>
>
> So the cookie isn’t copied and the DISPLAY isn’t updated.  I can’t see any
> errors in the logs and I can’t see anything different about this account.
>
>
>
> If I do a straight forward ssh -Y from the head node to a compute node
> from the bad account then that works fine – it’s only whatever is specific
> about the way that srun forwards X which fails.
>
>
>
> Any ideas or suggestions for debugging would be appreciated as I’m running
> out of things to try!
>
>
>
> Simon.
>
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> Charity No. 1053902.*
>
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