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

Kyle Hall kyle.m.hall at gmail.com
Fri Dec 7 14:24:14 CET 2018


+1
---
http://www.kylehall.info
ByWater Solutions ( http://bywatersolutions.com )
Meadville Public Library ( http://www.meadvillelibrary.org )
Crawford County Federated Library System ( http://www.ccfls.org )


On Wed, Dec 5, 2018 at 2:20 PM Jonathan Druart <
jonathan.druart at bugs.koha-community.org> wrote:

> 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
> _______________________________________________
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> bugs : http://bugs.koha-community.org/
>
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