Measure the amount of memory used?

[Jack Bates]

I wrote a content filter for Postfix with Python,
https://github.com/jablko/cookie

It should get started once, and hopefully run for a long time - so I'm
interested in how it uses memory:

 1) How does the amount of memory used change as it runs?

 2) How does the amount of memory used change as I continue to hack on
it, and change the code?

My naive thought was that I'd periodically append to a file, the virtual
memory size from /proc/[pid]/stat and a timestamp. From this a could
make a graph of the amount of memory used as my content filter runs, and
I could compare two graphs to get a clue whether this amount changed as
I continue to hack

 - but some Googling quickly revealed that measuring memory is actually
quite complicated? Neither the virtual memory size nor the "resident set
size" accurately measure the amount of memory used by a process

Has anyone else measured the memory used by a Python program? How did
you do it?