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https://issues.apache.org/jira/browse/JCR-798?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Jukka Zitting resolved JCR-798.
-------------------------------
Resolution: Fixed
Fixed in revision 529913 by explicitly removing all registered event listeners
at the beginning of the logout() method.
The EventConsumer class calls session.getAccessManager().isGranted() which in
turn (depending on the configured AccessManager) can access session internals
like the hierarchy and item state managers. This could previously happen in
parallel with the logout() method.
> ConcurrentModificationException during logout
> ---------------------------------------------
>
> Key: JCR-798
> URL: https://issues.apache.org/jira/browse/JCR-798
> Project: Jackrabbit
> Issue Type: Bug
> Components: core
> Environment: Jackrabbit 1.2.1
> Reporter: Martijn Hendriks
> Assigned To: Stefan Guggisberg
> Fix For: 1.3
>
> Attachments: currentObservationSession.patch
>
>
> We regularly get the following exception:
> java.util.ConcurrentModificationException
> at
> org.apache.commons.collections.map.AbstractReferenceMap$ReferenceEntrySetIterator.checkMod(AbstractReferenceMap.java:761)
> at
> org.apache.commons.collections.map.AbstractReferenceMap$ReferenceEntrySetIterator.hasNext(AbstractReferenceMap.java:735)
> at
> java.util.Collections$UnmodifiableCollection$1.hasNext(Collections.java:1009)
> at
> java.util.Collections$UnmodifiableCollection$1.hasNext(Collections.java:1009)
> at
> org.apache.jackrabbit.core.state.LocalItemStateManager.dispose(LocalItemStateManager.java:341)
> at
> org.apache.jackrabbit.core.WorkspaceImpl.dispose(WorkspaceImpl.java:170)
> at
> org.apache.jackrabbit.core.SessionImpl.logout(SessionImpl.java:1225)
> at
> org.apache.jackrabbit.core.XASessionImpl.logout(XASessionImpl.java:379)
> Two causes for this exception have been identified:
> (Taken from an email to the dev-list from Marcel Reutegger):
> > - session A reads some items I
> > - session B transiently removes items in I
> > - session A logs out and starts to iterate over I in LocalItemStateManager
> > (LISM)
> > - session B saves changes and removed items are evicted from A's LISM
> > - session A gets concurrent modification exception
> Another scenario is the following:
> - Session A gets the iterator of the values of (the primary cache of) an
> ItemStateReferenceCache in LocalItemStateManager.dispose.
> - Session B then does something that triggers the CacheManager.
> - The CacheManager then calls resizeAll, and evicts some items from the
> secondary cache of the ItemStateReferenceCache of which the
> LocalItemStateManager has a values iterator.
> - The garbage collector then runs and evicts the removed items also from the
> primary cache, which effectively modifies the set over which is iterated.
> Regards,
> Martijn Hendriks
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