What is heating the memory here? hashlib?

[Paulo da Silva]

I was unable to reproduce the situation using a simple program just
walking through all files>4K, with or without the seek, and computing
their shasums.
Only some fluctuations of about 500MB in memory consumption.

I'll look at this when I get more time, taking in consideration the
suggestions here posted.

For the time being, my work is done. With a small buffer size (16k) the
results produced were correct and no memory was leaked!

If I can find any explanation (if not embarrassing :-) ), I'll post it here.

Thank you all.
Paulo