Summary

Keypoints

Load and run

  • Use Julia from module system
  • Start a Julia shell session either with julia
  • run scripts with julia <script.jl>

Packages

  • Check for preinstalled packages
    • from the Julia REPL with the using or import command

Isolated environments

  • With a virtual environment you can tailor an environment with specific versions for Julia and packages, not interfering with other installed Julia versions and packages.

  • Make it for each project you have for reproducibility.

  • Julia has its own mechanism to create virtual environments.

  • HPC2N & LUNARC

    • The Julia installation is lean, no additional package besides the Base and and Standard Libraries are installed.

  • UPPMAX

    • Several packages are already installed

Batch mode

  • The SLURM scheduler handles allocations to the calculation nodes
  • Batch jobs runs without interaction with user
  • A batch script consists of a part with SLURM parameters describing the allocation and a second part describing the actual work within the job, for instance one or several Julia scripts.
  • Remember to include possible input arguments to the Julia script in the batch script.

Interactive work on calculation nodes

  • Start an interactive session on a calculation node by a SLURM allocation (similar flags)

    • At HPC2N: salloc …
    • At UPPMAX/LUNARC: interactive …

  • Follow the same procedure as usual by loading the Julia module and possible prerequisites.

  • Run Julia in Jupyter lab/notebook

  • Procedure is to use the IJulia package and start a jupyter notebook from the julia command line.

Parallel

  • You deploy cores and nodes via SLURM, either in interactive mode or batch
  • In Julia, threads, distributed and MPI parallelization can be used.

GPUs

  • You deploy GPU nodes via SLURM, either in interactive mode or batch
  • In Julia the CUDA package is handy

Not really clear? (5 min)

  • Discuss in breakout rooms
  • Learn from each other

Evaluation

You can find the evaluation form for the Julia part of the course here: TODO:link to eval

See also

Final words