[SLING-3285] ResourceResolver.isResourceType() creates admin session for every call with super type, slowing down processing

• Type: Bug
• Status: Closed
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: Resource Resolver 1.0.6
• Fix Version/s: Resource Resolver 1.1.0
• Component/s: ResourceResolver
• Labels: Performance
• Assignee: Carsten Ziegeler
• Reporter: Alexander Klimetschek
• Created: 14/Dec/13 02:29
• Updated: 04/Apr/14 09:05
• Resolved: 23/Dec/13 13:22

Description

SLING-2457 fixed the ACL issue with super type lookups, but at the cost of creating a new admin resource resolver for every super type lookup. If an inheritance chain contains multiple super types (N), a single call can trigger the creation of N admin sessions. Often this also happens for a number of resources per request, depending on the application, so you might end up creating many Jackrabbit JCR sessions per request. While creating a resource resolver / session is cheap, having too many at the same time has a big performance impact on the read performance due to increased concurrency in the JCR repository layer.

This affects:

• ResourceUtil.isA()
• Resource.isResourceType()
• ResourceResolver.isResourceType()
• implementation in ResourceResolverImpl.isResourceType() and getParentResourceType() [1]

A simple fix could be to cache a single admin resolver for the duration of the resource resolver containing it and reusing it for subsequent isResourceType() calls.

Another improvement could also be to cache the isResourceType() lookups - if this is a typical short-lived request resource resolver. Within a request resource type hierarchies are unlikely to change and should probably be stable (and with Jackrabbit Oak the session won't refresh anyway). The cache would simply be a map of "resource type" => "is also this resource type", so that the super lookups don't have to be done again and again. Often an application might iterate over a tree of data and looking for the same resource type again and again, so the hit rate for the cache will be high.

[1] https://svn.apache.org/viewvc/sling/trunk/bundles/resourceresolver/src/main/java/org/apache/sling/resourceresolver/impl/ResourceResolverImpl.java?revision=1537136&view=markup

Issue Links

• is cloned by: SLING-3301 Add internal component for hierarchy queries
• relates to: JCR-2768 Finalize method on SessionImpl