Carsten Ziegeler created SLING-3301:
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Summary: Add internal component for hierarchy queries
Key: SLING-3301
URL: https://issues.apache.org/jira/browse/SLING-3301
Project: Sling
Issue Type: Bug
Components: ResourceResolver
Affects Versions: Resource Resolver 1.0.6
Reporter: Alexander Klimetschek
Assignee: Carsten Ziegeler
Priority: Critical
Fix For: Resource Resolver 1.1.0
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
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