stateful caches (was Re: OBS Studio memory leak)

[Giovanni Biscuolo]

Hi Guillaume Le Vaillant and Guix Devels,

sorry for cross-posting but IMHO the workaround you found [1] for the memory
leak affecting a number of media processing applications is of interest
for many people potentially not subscribed to help-guix

AFAIK this was not filed as a Guix bug

Guillaume Le Vaillant <glv@posteo.net> writes:

> Ott Joon <ott.joon@tutanota.com> skribis:
>
>> Hey
>>
>> Tried the same thing in VLC and it freezes on GPU accel and starts
>> leaking memory while also becoming hard to kill.  Maybe this also
>> explains why some mpv GPU accel settings don't work also in the exact
>> same way.  I have an AMD RX 6900 XT on this machine.

[...]

> It looks like an issue with the shader cache of mesa.
> After clearing it, I don't see the memory leak anymore.

good catch: please can you tell us how you managed to spot that problem?
Did you straced it or did yoy find a related mesa bug report?

do you think this bug (is it a bug, right?) needs to be reported
upstream?

I'm asking this because I "feel" we (I mean Guix users) could do
something to help upstream removing this "status mismanagement"

> Could you try doing a "rm -r $HOME/.cache/mesa_shader_cache/*" and see
> if it also solves the issue for you?

AFAIU this is "just" another instance of the "mismanaged state" error
class, like the one(s) discussed back in Oct 2019 [2] and probably
periodically recurring since the beginning of some (many) the upstream
applications lifecycle.

Back then, Efraim Flashner was using this snippet [2] in his OS-config:

--8<---------------cut here---------------start------------->8---

;; This directory shouldn't exist
(file-system
  (device "none")
  (mount-point "/var/cache/fontconfig")
  (type "tmpfs")
  (flags '(read-only))
  (check? #f))

--8<---------------cut here---------------end--------------->8---

It seems that a similar snippet could also be useful for all
"~/.cache/*" :-O

Happy hacking! Gio'



[1] message id:87y1kozvny.fsf@robbyzambito.me

[2] message id:20191018073501.GB1224@E5400

-- 
Giovanni Biscuolo

Xelera IT Infrastructures

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