[JCR-314] Fine grained locking in SharedItemStateManager

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.9, 1.0, 1.0.1, 1.1, 1.1.1, 1.2.1, 1.2.2, 1.2.3
• Fix Version/s: 1.4
• Component/s: jackrabbit-core
• Assignee: Unassigned
• Reporter: Marcel Reutegger
• Created: 03/Feb/06 19:59
• Updated: 02/May/13 02:29
• Resolved: 18/Dec/07 10:42

Description

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.

Issue Links

• is depended upon by: JCR-935 ConcurrentModificationException during logout (cont'd)