[JCR-18] Multithreading issue with versioning

• Type: Bug
• 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, 1.3, 1.3.1
• Fix Version/s: 1.3.3
• Component/s: versioning
• Environment: Jackrabbit SVN Rev. 56918
• Assignee: Tobias Bocanegra
• Reporter: Felix Meschberger
• Created: 10/Nov/04 21:27
• Updated: 08/Oct/07 10:47
• Resolved: 26/Jun/07 08:01

Description

In a multithreading environment with two or more threads accessing the same version history, inconsistent state may be encountered. Concretely, the first thread is currently checking in the node to which the version history is attached while the second thread walks this same version history by means of a "self-built" iterator, which just accesses the successors of each version to get the "next" to visit.

At a certain point the second point may encounter an ItemNotFoundException with a stack trace similar to this:

javax.jcr.ItemNotFoundException: c9bd405b-dff4-46ef-845c-d98e073e473a
at org.apache.jackrabbit.core.ItemManager.createItemInstance(ItemManager.java:354)
at org.apache.jackrabbit.core.ItemManager.getItem(ItemManager.java:230)
at org.apache.jackrabbit.core.SessionImpl.getNodeByUUID(SessionImpl.java:494)
at org.apache.jackrabbit.core.version.VersionImpl.getSuccessors(VersionImpl.java:86)
....

It seems that the first thread has already filled the successor of the version, while the node is not yet accessible by the createItemInstance method.

This bug seems to not be enforcible, but it is easily reproducible.

Issue Links

• is related to: JCR-790 Possible deadlock during concurrent operations on versionable nodes
• is related to: JCR-962 Deadlocks in ConcurrentVersioningWithTransactionsTest
• relates to: JCR-754 Exception when concurrently adding nodes with JCA and XA transactions
• relates to: JCR-140 Versioning might no be thread safe