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

Note

Evaluation

You can find the evaluation form for the Julia part of the course here: https://forms.office.com/e/PzkkX3SvB1

See also

Note