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https://issues.apache.org/jira/browse/OPENJPA-453?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12716349#action_12716349
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Craig Russell commented on OPENJPA-453:
---------------------------------------
Ravi, I've given you contributor status on OpenJPA JIRA. Let me know if that
doesn't work for you.
> The race condition arises from the repeated use of the following logic in
> enhancement added code (expressed as pseudo code here):
> [PC object class].pc[SomeMethod]
> {
> if (pcStateManager == null)
> ... do something by default with current values in
> this object
> else
> {
> ... use pcStateManager, likely resulting in an
> eventual lock, and possibly in a call back to
> this object's PersistenceCapable interface
> methods
> ...
> }
> }
>The race condition arises because the check of the value of pcStateManager is
>obtained and used twice in succession without first locking the state manager.
>Another thread using and having locked the state manager has the time to alter
>the state of this pc object, including nulling out its pcStateManager
>reference.
The use of the multithreaded flag was intended to add a bit of overhead to the
StateManager in exchange for thread-safe behavior. It's understandable why a
"context" StateManager lock was used: it prevents many cases of deadlock for
multithreaded access.
But the footprint of sm->pc seems to be small. Would it be possible to use a
simple semaphore before calling the pc methods? For example,
void provideField(PersistenceCapable pc, FieldManager store, int field) {
if (multithreaded) {
FieldManager beforeFM = _fm;
_fm = store;
synchronized(this) {
pc.pcProvideField(field);
}
// Retaining original FM because of the possibility of reentrant calls
_fm = beforeFM;
} else {
FieldManager beforeFM = _fm;
_fm = store;
pc.pcProvideField(field);
// Retaining original FM because of the possibility of reentrant calls
_fm = beforeFM;
}
}
> Evicting embedded object nullifies statemanager
> -----------------------------------------------
>
> Key: OPENJPA-453
> URL: https://issues.apache.org/jira/browse/OPENJPA-453
> Project: OpenJPA
> Issue Type: Bug
> Environment: Kodo 4.1.4, Ms sql server 2005, jTDS 1.2, jdk 1.6
> Reporter: Christiaan
> Assignee: David Ezzio
> Attachments: OpenJPABug453Embedded.zip, openJPATestCase.zip,
> TestCaseEvictEmbedded.zip
>
>
> I am noticing the following behaviour: If evict() is called on an embedded
> object the statemanager is nullified which is in contrast to non-embedded
> objects. Subsequently, calling JDOHelper.getPersistenceManager() on the
> evicted embedded object returns null. Is this the correct behaviour?
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