Questions related to underlying logics for XWiki security and group cache

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ktc
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Questions related to underlying logics for XWiki security and group cache

ktc
Hi devs,

We run into a complicated issue related to XWiki cache and permissions. In
order to fix the issue, we would like to know some underlying logics for
XWiki security and group cache:

1. Why XWiki cache purge happens every 4 hours?
2. From our dashboards, we notice that every 4 hours, the security
authorization cache purge will wipe out most entries(from 50K to 5K). Why
this happens rather than selectively expiring 4-hour-old entries over time
gradually?
3. From our dashboards, we notice the user group cache dumps on an irregular
cadence. The number of entries will drop to nearly 0 on 12:00 and bounce
back at around 16:00 nearly every weekday. Do you know some reasons behind
that?
4. What's the underlying logic of XWiki purges SecurityCache entries? We
assume it will happen in one or both of the following cases:
        1. when a given page's permissions are changed
        2. when a given user is removed from a (XWiki-internal) group
    Is that correct?
5. We have a custom code called LDAP service. When our wiki user calls that
service, we wish to keep the cache for only a few minutes and then
invalidate the cache. So if our user calls again after a few minutes, it
will try to get reply from the service instead of the cache. For our case,
what method do you suggest to use when we invalidate SecurityCache entries?
Is there any side effect if we do that?

Thanks a lot for your help!



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ktc
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Re: Questions related to underlying logics for XWiki security and group cache

ktc
Hi devs,

Here are the graphs we mentioned in the above post.
<http://xwiki.475771.n2.nabble.com/file/t396587/Security_Cache.png>
The first is the security authorization cache, as you can see it will wipe
out most entries every 4 hour.
<http://xwiki.475771.n2.nabble.com/file/t396587/Group_Cache.png>
The second is the group cache, which is very weird.

BTW, if there are some documents related to security/group cache, that will
be very helpful, too.

Thanks in advance!



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