[jira] Assigned: (JCR-798) ConcurrentModificationException during logout

["Stefan Guggisberg (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/JCR-798?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Stefan Guggisberg reassigned JCR-798:
-------------------------------------

    Assignee: Stefan Guggisberg

> 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
>
> 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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