Installing Julia packages

This exercise aims to give you hands-on experience with installing Julia packages and contrasting some different approaches. It should take approximately 30 minutes to an hour to complete (potentially more when also conducting the benchmark exercises). To get started, choose a Julia package with a non-trivial dependency tree. It is recommended to choose a Julia package related to your area of research, but if you are really lacking inspiration, you can complete this exercise using the TightBindingToolkit package.

You can find the relevant documentation in the “R and Julia” section of the GSSI training material and in the Julia package management section in the VSC Docs.

Here are the different methods you can use to install Julia packages on a VSC cluster:

• using centrally installed Julia packages from software modules (use module spider to find them; note that these packages are usable in Julia but are not part of your own project environment)
• using a Julia project environment (Pkg.activate() + Pkg.add(), which creates a Project.toml and Manifest.toml in your project directory) (note: by default ~/.julia; consider moving the depot to $VSC_DATA to avoid filling up the quota of your home directory)
• using a Julia project environment on top of a software module, inheriting the packages already provided by that module (see the “Julia environment on top of software module” section in the Julia package management section in the VSC Docs)
• using an Apptainer container (see the building containers exercise)

NOTE: Make sure to keep the different installations separated, mixing approaches will likely cause problems. Also be aware that Julia package installations can consume a lot of disk space, and that precompiling packages takes a significant amount of time and compute resources.

After trying the different installation approaches, compare them with respect to the following characteristics:

• ease of use
• time it takes to install the package (including precompilation)
• disk space and number of files consumed by the installation
• reproducibility
• portability (e.g., does the same environment work on different clusters or with different Julia versions? Note that depots and project environments are tied to the major and minor version of Julia used to create them)
• performance: ideally, use a benchmark (check if the source of the chosen package includes one) to compare runtimes for the different installations. Try to explain possible differences from a theoretical point of view and connect to what you observe in practice.