[keycloak-user] All realms will all linked entities being read at bootstrap

KC startups longer then default JBoss 5 min limit and got rolled back. all realms fetch from org.keycloak.services.managers.UserStorageSyncManager#bootstrapPeriodic Sequence is following: 1. KeycloakApplication.setupScheduledTasks is called on bootstrap 2. All realms are fetched inside UserStorageSyncManager#bootstrapPeriodic 3. During each realm fetch, RealmEntity is wrapped to CachedRealm by RealmCacheSession#getRealm 4. In CachedRealm constructor, it reads all RealmEntity collections 5. Sql selects fired for all RealmEntity collections (RealmAttributeEntity, AuthenticationFlowEntity, RequiredCredentialEntity, etc) I see there was optimization to fetch only realms with user storages: https://issues.jboss.org/browse/KEYCLOAK-8555. This didn't help me because I have user federation provider in each realm. Also I see hibernate 1st level cache clear was advised here: https://github.com/keycloak/keycloak/pull/6012. This also did not help, probably because too much data is being read. I suggest to modify realm-extraction code at UserStorageSyncManager#bootstrapPeriodic so it will select only required info from DB. I am ready to develop this change, what do you think about it?