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From "angela (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (JCR-2950) CachingEntryCollector ineffective if number of accessed policies exceeds cache size
Date Tue, 26 Jun 2012 13:25:44 GMT

    [ https://issues.apache.org/jira/browse/JCR-2950?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13401380#comment-13401380
] 

angela commented on JCR-2950:
-----------------------------

ok... so i would suggest that we don't start changing yet another part....

i did run the ConcurrentReadAccessControlledTreeTest performance test that should provide
some results for
situations where the entry-cache limit is reached with JCR-3352 included and with the 3 different
cache update variants.

i get the impression that overall performance was similar in case of synchronized and parallel
access.
the throttled update looks to be slightly slower on average (but that necessarily doesn't
mean too much and i am not
convinced that the difference is really significant). what strikes me however is, that with
the 'T' strategy the performance
test seems to be stalling at some point.... but i have to check that one more time... what
also strikes me is that
the number of ms to read 10000 random items seems to vary much more in the 'T' case (all completed
cycles are
reported with system output even those from the warm-up phase).

in order to get a better feeling for that i added a shortcut in the beginning of the "throttledUpdateCache"
method that
prevent entering the concurrent map in case the target node is not access controllable...
but from the pure figures
this didn't seem to have an effect.
                
> CachingEntryCollector ineffective if number of accessed policies exceeds cache size
> -----------------------------------------------------------------------------------
>
>                 Key: JCR-2950
>                 URL: https://issues.apache.org/jira/browse/JCR-2950
>             Project: Jackrabbit Content Repository
>          Issue Type: Improvement
>          Components: jackrabbit-core, security
>    Affects Versions: 2.2.12, 2.4.2, 2.6
>         Environment: Repository with ACEs > 1000
>            Reporter: Honwai Wong
>            Assignee: angela
>         Attachments: CachingEntryCollector.ConcurrentCache-trunk.patch, JCR-2950-concurrent-cache-2.patch,
JCR-2950-futures.patch, JCR-2950-futures_2.patch, JCR-2950-futures_3.patch, JCR-2950-futures_4.patch,
JCR-2950-refactor+rootnode.patch, JCR-2950-refactor+rootnode_2.patch , JCR-2950-refactor+rootnode_3.patch,
JCR-2950-refactor+rootnode_4.patch, JCR-2950-refactor+rootnode_5.patch, JCR-2950-refactor+rootnode_6.patch,
JCR-2950-refactor+rootnode_7.patch, JCR-2950-refactor.patch, JCR-2950-throttle.patch, JCR-2950-throttle2.patch,
JCR-2950_performance_tests.patch.gz
>
>
> The CachingEntryCollector's cache (LRUMap, max size: 1000) seems to become ineffective
in case there are more than 1000 ACEs present in the repository. Since access to the cache
is synchronized, many threads are basically blocked, waiting to get access to the cache.
> Java callstack:
> at org/apache/jackrabbit/core/security/authorization/acl/CachingEntryCollector.getEntries(CachingEntryCollector.java:99(Compiled
Code))
> at org/apache/jackrabbit/core/security/authorization/acl/EntryCollector.collectEntries(EntryCollector.java:134(Compiled
Code))
> at org/apache/jackrabbit/core/security/authorization/acl/CompiledPermissionsImpl.canRead(CompiledPermissionsImpl.java:250(Compiled
Code))
> at org/apache/jackrabbit/core/security/DefaultAccessManager.canRead(DefaultAccessManager.java:251(Compiled
Code))
> at org/apache/jackrabbit/core/ItemManager.canRead(ItemManager.java:426(Compiled Code))
> at org/apache/jackrabbit/core/ItemManager.createItemData(ItemManager.java(Compiled Code))
> at org/apache/jackrabbit/core/ItemManager.getItemData(ItemManager.java:379(Compiled Code))
> at org/apache/jackrabbit/core/ItemManager.itemExists(ItemManager.java:292(Compiled Code))
> at org/apache/jackrabbit/core/ItemManager.itemExists(ItemManager.java:464(Compiled Code))
> at org/apache/jackrabbit/core/session/SessionItemOperation$1.perform(SessionItemOperation.java:49(Compiled
Code))
> at org/apache/jackrabbit/core/session/SessionItemOperation$1.perform(SessionItemOperation.java:46(Compiled
Code))
> at org/apache/jackrabbit/core/session/SessionItemOperation.perform(SessionItemOperation.java:187(Compiled
Code))
> at org/apache/jackrabbit/core/session/SessionState.perform(SessionState.java:200(Compiled
Code))
> at org/apache/jackrabbit/core/SessionImpl.perform(SessionImpl.java:355(Compiled Code))
> at org/apache/jackrabbit/core/SessionImpl.itemExists(SessionImpl.java:751(Compiled Code))

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