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https://issues.apache.org/jira/browse/JCR-314?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12495700
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Jukka Zitting commented on JCR-314:
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I briefly reviewed the patches, good work! I like how you've applied the
strategy pattern.
My main concern is that this still doesn't address the concurrency limitations
in the current persistence managers. Should that be handled as a separate
issue? A more general issue is that this whole ISM core keeps getting more
complex, and adding 1+2 new interfaces and all the implementing classes doesn't
really help things. I'm not sure what to do about that...
Also, it would be nice if we had at least a few parallel test cases for
excercising such code.
> Fine grained locking in SharedItemStateManager
> ----------------------------------------------
>
> Key: JCR-314
> URL: https://issues.apache.org/jira/browse/JCR-314
> Project: Jackrabbit
> Issue Type: Improvement
> Components: core
> Affects Versions: 0.9, 1.0, 1.0.1, 1.1, 1.1.1, 1.2.1, 1.2.2, 1.2.3
> Reporter: Marcel Reutegger
> Attachments: FineGrainedISMLocking.patch, ISMLocking.patch
>
>
> The SharedItemStateManager (SISM) currently uses a simple read-write lock to
> ensure data consistency. Store operations to the PersistenceManager (PM) are
> effectively serialized.
> We should think about more sophisticated locking to allow concurrent writes
> on the PM.
> One possible approach:
> If a transaction is currently storing data in a PM a second transaction may
> check if the set of changes does not intersect with the first transaction. If
> that is the case it can safely store its data in the PM.
> This fine grained locking must also be respected when reading from the SISM.
> A read request for an item that is currently being stored must be blocked
> until the store is finished.
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