[Pkg-mailman-hackers] Bug#1014037: mailman3-web: Possible memory leak: uwsgi OOMs after a few weeks

[Antoine Beaupré]

On 2025-01-15 10:04:54, Antoine Beaupré wrote:

[...]

> This thread on the upstream mailman mailing list mentions people don't
> have this kind of problem with gunicorn:
>
> https://lists.mailman3.org/archives/list/mailman-users@mailman3.org/thread/QCTB7Y6W7I7GDRCIJKFNEVQB7DSNC4WG/
>
> So I'm tempted to reassign this bug report to the uwsgi package,
> although perhaps the mailman3-web package should work on switching to
> the different process manager than uwsgi, at least as an option, to
> resolve that issue.
>
> We'll be experimenting with gunicorn and report back here.

So we've done that, and here's our report back.

It's been a little over 24 hours and we can already say that we still
get OOMs under gunicorn.

The interesting thing is that it's a different process showing the OOM
condition: instead of it being gunicorn itself (which you'd expect if it
was designed like uwsgi or apache2-mod-wsgi), it's Python itself eating
all the memory. See this comment:

https://gitlab.torproject.org/tpo/tpa/team/-/issues/41957#note_3151902

Directly link to the per-process memory graph:

https://gitlab.torproject.org/-/project/441/uploads/c8ebf60612c426688e651853f251edd5/mem3.png

So my theory, at this moment, is that the assumption that the problem is
related to the process manager (uwsgi or apache or gunicorn) is
incorrect; this is actually and truly a memory management issue inside
the Python process running mailman3-web.

This bug report would, therefore, seem to be filed at the right place.

The question at this point is: how do we profile this any further? Any
advice? run a memory profiler like austin?

a.

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