[
https://issues.apache.org/jira/browse/OPENJPA-2767?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16964967#comment-16964967
]
Will Dazey commented on OPENJPA-2767:
-------------------------------------
I am adding back the extra synchronization to
`MetaDataRepository.processRegisteredClasses()` for `_registered` so that
`MetaDataRepository.register()` can safely add to `_registered`. This
synchronization block was in the original code, but was removed in the previous
fix as I thought method synchronization was enough. This was an oversight in my
previous fix and I shouldn't have removed that sync block.
Exception:
```
Caused by: java.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextNode(HashMap.java:1456)
at java.util.HashMap$KeyIterator.next(HashMap.java:1480)
at
java.util.AbstractCollection.finishToArray(AbstractCollection.java:243)
at java.util.AbstractCollection.toArray(AbstractCollection.java:210)
at
org.apache.openjpa.meta.MetaDataRepository.processRegisteredClasses(MetaDataRepository.java:1638)
at
org.apache.openjpa.meta.ClassMetaData.getPCSubclasses(ClassMetaData.java:377)
```
Due to the difficulties in testing these race conditions, I did not include a
test with the patch. However, for what it is worth, the patch was tested in an
application server getting these intermittent ConcurrentModificationExceptions
and they noticed them go away. I am currently having our performance team make
sure performance is not negatively impacted by this change.
> Incomplete ValueMapDiscriminatorStrategy cache
> -----------------------------------------------
>
> Key: OPENJPA-2767
> URL: https://issues.apache.org/jira/browse/OPENJPA-2767
> Project: OpenJPA
> Issue Type: Bug
> Reporter: Will Dazey
> Assignee: Will Dazey
> Priority: Minor
> Fix For: 2.2.3, 3.1.1
>
> Attachments: OJ2767_2.2.x_v4.patch, OJ2767_2.2.x_v4_p2.patch
>
> Time Spent: 1h 40m
> Remaining Estimate: 0h
>
> There exists the possibility that the discriminator class cache in
> ValueMapDiscriminatorStrategy was originally created before the server fully
> loaded all classes. If this happens, the cache is incomplete and needs to be
> rebuilt. A simple enough strategy would be to just try rebuilding the cache,
> before giving up and throwing a CNFE, and check again.
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