[Koha-devel] Cache::Memory must be removed (21955)

[Renvoize, Martin]

I agree on its removal too.

On Thu, 6 Dec 2018, 8:26 am Fridolin SOMERS <fridolin.somers at biblibre.com
wrote:

> Indeed, this is a big behavior error we found a few month ago.
> I think we shared it in mailing but I can find how.
> This is a big issue when you change an HTML systempreference like
> "opacnav", you see the change and when refresh its gone (you see the
> other plack worker).
> We solved by installing memached everywhere.
>
> Maybe we can just disable Cache::Memory when Plack mode is used.
> Then I say we need a C4::Context->is_psgi() method :
> https://bugs.koha-community.org/bugzilla3/attachment.cgi?id=76477
>
> Programing is sometimes so wierd ;)
>
> Regards,
>
> Le 05/12/2018 à 20:20, Jonathan Druart a écrit :
> > Hi devs,
> >
> > I am still recovering from my holidays and I think I caught a quite big
> fish.
> >
> > After an interesting track game I will explain why I am suggesting to
> > remove Cache::Memory that is currently used as fallback for the L2
> > cache.
> >
> > What I tried to fix:
> > Jenkins is complaining about selenium tests (regressions.t) failing on
> > 18.05, it is a succession of events and bugs that were not linked at
> > first glance.
> >
> > Here are the different steps I went though:
> > - On bug 21426 we noticed that USE_MEMCACHED was not taken into
> > account. If set to "no" the default memcached config was defined in
> > the koha-config.xml file anyway
> > - A new regression selenium test was added on bug 21777 to catch the
> > presence of an audio alert on the circulation page
> > - Investigating the failing tests I noticed that koha-testing-docker
> > was not setting the memcached config on the 18.05 branches (I guess
> > the image has not been rebuilt yet)
> > search_utf8.t output "Warning: script running in daemon mode, without
> > recommended caching system (memcached)."
> > - I also find that [% Koha.Preference('AudioAlerts') %] did not return
> > the value set by the tests, but the value that the DB has before the
> > tests were launched
> > => It is a cache issue!
> > - ...but only when memcached is not set...
> > - Reading Koha::Cache->new we can notice that Cache::Memory is used
> > for the L2 cache when memcached is not defined in the config
> >
> > And so we have the problem: If a value is set in the cache by a Plack
> > worker, it will not be available from another one, as the L2 cache is
> > not shared (!)
> >
> > To recreate easily the problem you can:
> > - remove the memcached config
> > - edit intranet-bottom.inc and add
> > ===[% Koha.Preference('AudioAlerts') %]===
> > - restart plack
> > - Modify the value of AudioAlerts (using the UI)
> > - Reload the page (reload several times if the value is still correct,
> > it will depend on which worker will serve the request)
> >
> > Solution:
> > I am considering removing Cache::Memory unless somebody else has a
> better idea
> > Bug 21955 - Cache::Memory should not be used as L2 cache
> >
> > Note that it should not affect a lot of people as everybody is
> > supposed to have memcached configured and working correctly!
> >
> > Cheers,
> > Jonathan
> > _______________________________________________
> > Koha-devel mailing list
> > Koha-devel at lists.koha-community.org
> > http://lists.koha-community.org/cgi-bin/mailman/listinfo/koha-devel
> > website : http://www.koha-community.org/
> > git : http://git.koha-community.org/
> > bugs : http://bugs.koha-community.org/
> >
>
> --
> Fridolin SOMERS <fridolin.somers at biblibre.com>
> BibLibre, France - software and system maintainer
> _______________________________________________
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