JupyterHub - Revision history

Torradeflot: /* GPUs */

2026-04-08T08:14:19Z

GPUs

2026-04-08T08:10:10Z

GPUs

2026-02-24T14:26:19Z

Known problems

2026-01-15T06:21:55Z

SageMath

2026-01-15T06:20:22Z

2026-01-15T06:18:08Z

Known errors

2026-01-15T06:17:00Z

Using a Singularity image as a Jupyter kernel

2026-01-15T06:16:35Z

Running notebooks through HTCondor

2026-01-15T06:15:50Z

2026-01-15T06:07:38Z

Jupytext

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      GPU-a2361e9d-c520-684b-b21b-60cc3a59b05b
-You can then track the GPU utilization (memory and load) using the GPU Dashboard in the left sidebar
+You can track the GPU utilization (memory and load) using the GPU Dashboard in the left sidebar
 == Code samples ==

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 == GPUs ==
-The way to identify the GPUs that are assigned to your job is:
+The GPUs that are assigned to your job are listed in the environment variable CUDA_VISIBLE_DEVICES. In a terminal run "echo $CUDA_VISIBLE_DEVICES". The environment variable contains a list of comma-separated GPU ids. With this you will already know how many gpus are assigned to your job. If the variable does not exist, there are no gpus assigned to the job
-* list the gpus with nvidia-smi, in a terminal run "nvidia-smi -L", and look for the gpus you've been assigned. Remember their indexes (integers from 0 to 7)
+    [torradeflot@gpu05 ~]$ echo $CUDA_VISIBLE_DEVICES
+    GPU-a2361e9d-c520-684b-b21b-60cc3a59b05b
 == Code samples ==

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 = Known problems =
 == Error 500: Internal Server Error ==
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 This is a generic error. Means that the jupyterlab server failed. This could be for different reasons:
-* Your HOME folder is full. Log in to "ui.pic.es" and run "quota" to check the usage vs quota. If it is full you'll have to free up space.
+* [[#HOME_folder_is_full|Your HOME folder is full]]
 == 504 Gateway timeout ==

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 [https://www.sagemath.org/ SageMath] is particularly interesting for Cosmology because it allows symbolic calculations, e.g. deriving the equations of motions for the scale factor starting from a customised space-time metric.
-==== Standard cosmology examples ====
+'''Standard cosmology examples'''
 * The Friedman equations for the FLRW solution of the Einstein equations.
@@ Line 319: / Line 319: @@
 [[File:Screenshot_Sage06.png|300px]]
-==== Enabling SageMath environment in Jupyter ====
+'''Enabling SageMath environment in Jupyter'''
 If you have never initialized mamba, run:
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 Next time you go to your Jupyter dashboard you will find the sage environment listed there.
 == Dask ==

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 == Software of particular interest ==
 === SageMath ===
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 This is probably because there's some error when starting the jupyterlab server. First of all, shutdown the notebook server and [[#Logs|check the logs]] to better identify the problem. If you don't see the source of the error, try to [[#Clean_workspaces|clean the workspaces]] and launch a notebook again.
 == Loading libraries is very slow ==

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      rm *
-= Known errors =
+= Known problems =
 == Error 500: Internal Server Error ==
@@ Line 429: / Line 429: @@
 This is probably because there's some error when starting the jupyterlab server. First of all, shutdown the notebook server and [[#Logs|check the logs]] to better identify the problem. If you don't see the source of the error, try to [[#Clean_workspaces|clean the workspaces]] and launch a notebook again.
-== Install ROOT ==
+== ROOT Installation ==
 Environment creation and kernel installation

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 * Create the '''kernel.json''' file inside it with the following content:
+  {
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     "display_name": "singularity-kernel"
+  }
 Refresh or start the jupyterlab interface and the singularity kernel should appear in the launcher tab

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 == Running notebooks through HTCondor ==
-After developing a notebook, you might want to run it with different configurations. The
+After developing a notebook, you might want to run it as a script with different configurations. The
 following documentation explains
 [[notebook_htcondor|how to run a notebook through HTCondor.]]
 = Troubleshooting =

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 https://jupytext.readthedocs.io
-=== Example ===
+'''Example'''
 If you had a notebook (.ipynb file) containing only the cell below, tracked in a git repository