Re: [keycloak-dev] Issues with clustered invalidation caches

I was looking at the cache issue reported by customer. I found the cause of it and couple of other related issues: KEYCLOAK-3857 - Bad performance with clustered invalidation cache when updating object KEYCLOAK-3858 - Removing model object send lots of invalidation messages across cluster KEYCLOAK-3859 - Lots of userCache invalidation messages when invalidating realm KEYCLOAK-3860 - All realm users are invalidated from cache when removing some realm object In shortcut, our cache works fine in local mode. But in cluster, there are issues with the invalidation caches . We don't have issues with stale entries, but this is purchased but lots of various performance issues like: - There are lots of invalidation messages sent across the cluster - Eviction on the node, which received invalidation event, is also very uneffective. For example evicting realm with 1000 roles needs to call 1000 predicates, which iterates the cache 1000 times. - Invalidation cache doesn't allow to differ between the context why the object was invalidated. For example when I update realm settings on node1, I need to invalidate just the CachedRealm object, but not all the other objects dependent on the realm. However the invalidation event received on node2 doesn't know, if I invalidated CachedRealm because of realm update or because of realm removal. So for more safety, it assumes removal, which evicts all realm objects! See https://issues.jboss.org/browse/KEYCLOAK-3857 for details. - Finally we have the workaround with the "invalidation.key" objects in our invalidation caches. This is currently needed because when invalidating object on node1, the invalidation event is NOT received on node2 unless the object is there. Hence the workaround with the "invalidation.key" records just to avoid this limitation of invalidation cache. For solve all these issues, I propose: - Instead of relying on invalidation caches, we will send notification across cluster what happened (eg. message "realm XY was updated"). All the nodes will receive this notification and will evict all their locally cached objects accordingly and bump their revisions locally. This would be much more stable, performant and will allow us to remove some workarounds. Some details: - The caches "realms" and "users" won't be "invalidation" caches, but they will be "local" caches. - When any object needs to be removed from cache because of some reason (eg. updating realm), the notification message will be sent from node1 to all other cluster nodes. We will use the replicated cache for that. Node1 will send the notification message like "realm XY was updated" . - Other cluster nodes will receive this message and they will locally trigger evictions of all the objects dependent on particular realm. In case of realm update, it's just the CachedRealm object itself. In case of realm removal, it is all realm objects etc. - Note message will contain also context "realm XY was updated" or "realm XY was removed" . Not just "invalidate realm XY". This allows much more flexibility and in particular avoid the issues like https://issues.jboss.org/browse/KEYCLOAK-3857 . - We already have replicated cache called "work", which we are using to notify other cluster nodes about various events. So we will just use this one. No need to add another replicated cache, we will probably just need to configure LRU eviction for the existing one. - Also note that messages will be always received. We won't need workaround with "invalidation.key" objects anymore. - Also we don't need recursive evictions (which has very poor performance. See https://issues.jboss.org/browse/KEYCLOAK-3857 ), because receiving node will know exactly what happened. It will remove objects just the same way like the "sender" node. - Finally the amount of traffic sent across the cluster will be much lower. This sounds like the big step, but IMO it's not that bad :) Note that we already have all the predicates in place for individual objects. The only change will be about sending/receiving notifications across cluster. I think I am able to prototype something by tomorrow to doublecheck this approach working and then finish it somewhen middle next week. WDYT? Marek _______________________________________________ keycloak-dev mailing list keycloak-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/keycloak-dev