Need to deal with already loaded modules in environment

[ccarouge]

Currently, benchcab loads modules but does not check or deal with already loaded modules. So if someone has netcdf, an intel compiler or MPI loaded, benchcab will return a module load error.

Should we use module switch instead? I haven't checked if switch works when no equivalent module is already loaded.

[bschroeter]

I've often seen a module purge being used prior to loading any modules and then loading the required set of modules on an empty module environment. Are there any issues with this approach?

[ccarouge]

If we do a module purge, we nuke pbs and have to load it again. It also nuke conda but I'm not sure if it's a problem. So I thought module switch was simpler. But benchcab could do a module purge+module load pbs when it is setting the environment instead.

The purge route is safer as it avoids dealing with weird issues when people load modules in their .bashrc.