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! -- Sent from: http://xwiki.475771.n2.nabble.com/XWiki-Dev-f475773.html