Program uses twice as much memory in Python 3.6 than in Python 3.5

Steve D'Aprano steve+python at
Wed Mar 29 20:12:22 EDT 2017

On Thu, 30 Mar 2017 07:19 am, Jan Gosmann wrote:

> Running further trials indicate that the problem actually is related to
> swapping. If I reduce the model size in the benchmark slightly so that
> everything fits into the main memory, the problem disappears. Only when
> the memory usage exceeds the 32GB that I have, Python 3.6 will acquire
> way more memory (from the swap) than Python 3.5.

If you can demonstrate this effect using simple example code without the
external dependencies (using nothing but the standard library) and people
can replicate it, I think it should be reported as a bug.

If you are right, it does sound like a performance regression. Maybe there's
a way to fix that.

“Cheer up,” they said, “things could be worse.” So I cheered up, and sure
enough, things got worse.

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