[firedrake] leaking memory

[Hiroe Yamazaki]

Dear all,

I am experiencing a memory leak in our vertical slice model and wonder
if there is any possibility of leaking memory associated with
.assign(). Here I have a stand-alone code with the same function
spaces and variable settings we use in the slice model:

https://bitbucket.org/hyamazak/test_files/src/f455e7e68722c9264845a8426ba91cc040d3f933/test_memory.py?at=master

What I do here is just doing

new.vars += Deltavars
old.vars.assign(new.vars)

over and over again, and I see a constant increase of the memory usage
both on my Linux and Macbook. I believe new.vars += Deltavars is not
the source of leaking and wonder if there is any problem with doing
old.vars.assign(new.vars).

Do let me know if you have any ideas,

all the best,
Hiroe