Reducing permanent memory storage in BoundaryDiscreteModel and DiscreteModelPortion ?

[amartinhuertas]

Hi @fverdugo, @santiagobadia

while taking a careful look at the current implementation of BoundaryDiscreteModel and DiscreteModelPortion, I am wondering whether it is possible (or not) to reduce the amount of permanent memory storage that these data types require.

In particular, the former stores a reference to the background model here:

Gridap.jl/src/Geometry/BoundaryDiscreteModel.jl

Line 3 in 5bb96bd

bgmodel::DiscreteModel

and the latter here:

Gridap.jl/src/Geometry/DiscreteModelPortions.jl

Line 6 in 5bb96bd

parent_model::DiscreteModel{Dc,Dp}

The former member variable seems not to be used, while the latter, only in the get_parent_model getter, which I am not sure if it is actually used or not.

The motivation behind not requiring these references is that the memory occupied by the models from which these are created can be removed early via GC.

Let me know your thoughts!