Author Topic: running ovito on cluster  (Read 297 times)

s_sengupta

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running ovito on cluster
« on: August 09, 2018, 02:13:36 PM »
Dear users,

I am trying to run a python script on a cluster using ovitos. On running it on the head node, I get the following messages- failed to get the current screen resources
QXcbConnection: XCB error: 170 (Unknown), sequence: 170, resource id: 90, major code: 146 (Unknown), minor code: 20
But, the code runs after that.
However if i submit a job, it fails to run altogether. The error message i get is
QXcbConnection: Could not connect to display localhost:16.0
/cm/local/apps/slurm/var/spool/job46728/slurm_script: line 9: 1934144 Aborted                 ovitos cluster.py

Could you please suggest a solution ?

Alexander Stukowski

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Re: running ovito on cluster
« Reply #1 on: August 09, 2018, 02:32:12 PM »
Hi,

Under Linux, OVITO will automatically try to connect to a running X server if there is one. Even though it is not showing any graphical user interface, this also applies to the script interpreter "ovitos". That's because image rendering via hardware-accelerated OpenGL requires the GLX extension to the X window system.

The detection is based on the DISPLAY environment variable. If it is set, which seems to be the case on your compute node (maybe because you captured all environment variables from the login node during job submission), ovitos thinks an X server is running and tries to connect to it. This fails. The solution to this problem is to clear the DISPLAY variable right before running ovitos, e.g.:

   export DISPLAY=
   ovitos cluster.py ...

-Alex

s_sengupta

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Re: running ovito on cluster
« Reply #2 on: August 09, 2018, 02:40:21 PM »
Thank you. Its working now.