A Personal Hierarchy Mirroring the System Hierarchy

Suppose you as a user wants to have personal modules that work as part of the software hierarchy. You might want to do that if you are a library or parallel application developer. You might want to test libraries or parallel applications before making them publically available. These are two possible of many that you might want to mirror the software hierarchy. So how to go about it.

The simplest to understand (but not implement) is to just copy over the entire compiler-mpi tree to your account and then tweek the compiler and mpi modules to point inside your directory. Once you have done that, you can add the modules that you need.

But that it work. Is there something easier to do? Yes there is. There is much easier method (but do not implement this one either). Just copy over the compiler and mpi modules you wish to have in your tree. Then add an additional directory for your packages to prepend to $MODULEPATH. However this is still problematical as the site might change the system compiler modules tomorrow but your copy this compiler module will be out of date.

So Lmod provides a way to get the contents of the system compiler which then you can add on to. You can use the inherit() function to “import” the same named module in the module tree.

To make things concrete, let’s assume that are a boost developer and the system has a boost library as well. The system boost version is 1.8 and you are working on 1.9. There is a system gcc 9.1 module. You create the following directory: $HOME/my_modules and under there you create Core, Compiler and MPI directories:

$ mkdir -p ~/my_modules/{Core,Compiler,MPI}

You also set the following environment variable:

$ export MY_MODULEPATH_ROOT=$HOME/my_modules

When this is set up you will do:

$ module use ~/my_modules/Core

Then in the file ~/my_modules/Core/gcc/9.1.lua you have:

local compiler = "gcc"
local MP_ROOT  = os.getenv("MY_MODULEPATH_ROOT")
local version  = "9"

prepend_path("MODULEPATH", pathJoin(MP_ROOT, "Compiler",compiler,version))

Suppose you also have the system intel/19.0.5 module. Then you would need at ~/my_modules/Core/intel/19.0.5.lua you have:

local compiler = "intel"
local MP_ROOT  = os.getenv("MY_MODULEPATH_ROOT")
local version  = "19"

prepend_path("MODULEPATH", pathJoin(MP_ROOT, "Compiler",compiler,version))

It would be best to mark your versions of the compilers (and mpi modules if they exist) as defaults. Module default are chosen over the highest version. The easiest way to mark module as the default is with a symbolic link:

$ cd ~/my_modules/Core/intel; ln -s 19.0.5.lua default
$ cd ~/my_modules/Core/gcc;   ln -s 9.1.lua    default

Then to support your personal boost 1.9 module for gcc goes at ~/my_modules/Compiler/gcc/9/boost/1.9.lua. And the boost 1.9 module for the intel 19.0.5 goes at ~/my_modules/Compiler/intel/19/boost/1.9.lua

Note that here I have used the major version number for the compiler modules. Here I have assumed that all gcc 9.* version work the same. You can do this or use the full version whichever works for you. For each compiler version you will have to have your own personal version as well.

MPI versions

If you wish to have a full personal compiler-MPI hierarchy mirroring the system one, you need to add mpi stack modulefiles as well. Assuming that you have an impi 19.0.5, you will place at ~/my_modules/Compiler/intel/19/impi/19.0.5.lua:

local compiler   = "intel"
local MP_ROOT    = os.getenv("MY_MODULEPATH_ROOT")
local c_version  = "19"
local mpiNm      = impi
local m_version  = "19"

prepend_path("MODULEPATH", pathJoin(MP_ROOT, "MPI",compiler,c_version,mpiNm,m_version))

Then your parallel application ACME version 1.3 will have a modulefile found at ~/my_modules/MPI/intel/19/impi/19/acme/1.3.lua

An example of setting up a user can be found in the source in the rt/user_inherit directory. In the mf directory is the “system” directory and the user_mf directory is a user supplied tree.