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https://issues.apache.org/jira/browse/OPENJPA-285?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Pinaki Poddar updated OPENJPA-285:
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Attachment: JIRA-285.patch.2.txt
Would it be possible to run this patch in Geronimo environment?
This patch
1. changes all field types of Class to String in PCRegistry$Meta
2. Retains all method signature the same. The constructor of Meta translates
all input Class arguments to their stringfied form
3. Reverts all changes of the earlier patch in PCEnhancer
4. The class names held in PCRegistry$Meta are converted to Classes in
PCRegistry. The classloader used to load these classes is always the same
classloader that loaded the user-defined persistence capable class.
> Multiple deploy/undeploy leaks memory in PCRegistry
> ---------------------------------------------------
>
> Key: OPENJPA-285
> URL: https://issues.apache.org/jira/browse/OPENJPA-285
> Project: OpenJPA
> Issue Type: Bug
> Components: kernel
> Environment: Geronimo
> Reporter: Pinaki Poddar
> Attachments: JIRA-285.patch.2.txt, JIRA-285.patch.txt
>
>
> Kevin Miller reported:
> Geronimo is running out of PermGen space in some simple deploy/ undeploy
> scenarios involving OpenJPA. The cause of the problem seems to be the _metas
> table in PCRegistry. _metas is a ConcurrentReferenceHashMap with WEAK
> reference keys and HARD reference values. The keys are the PersistenceCapable
> classes. While the values are the metadata for these classes which are
> maintained by the internal Meta class.
> The cause of the ClassLoader memory leak is simple -- if any of the
> objects/classes held by the Meta class (e.g. fieldTypes) have also been
> loaded by the same ClassLoader used to load the PersistenceCapable class, the
> PersistenceCapable class (the weak key) will never be GCed. The value of the
> HashMap entry will always maintain a hard reference to the ClassLoader. Since
> the ClassLoader will never be GC'ed, the the the pcClass Class object will
> never be GC'able...
> The problem can be easily recreated using current Geronimo trunk and the
> Geronimo Daytrader application.
> Patrick Linskey suggested:
> Change PCRegistry.fieldTypes to be String[] instead of Class[], and
> dematerialize them as needed.
> Robert Burrell Donkin/Marc Prud'hommeaux both pointed out that alternatives
> such as to
> listen for the death of a ClassLoader and manually unregistering metadata
> would be more costly in terms of complexity.
> This patch follows Patrick's suggestion.
> 1. Changes the Meta.fieldTypes to String[] from Class[]
> 2. Adapts the enhanced bytecode accordingly to the modified method signatures
> 3. PCRegistry getFieldTypes() load the fields' declared type using the same
> loader that loaded the owner pc class.
> Note: For a class C and its field f, CL(c) == CL(f) is not always true.
> (Kevin Miller)
> But CL(c) will be able to load declared type of f either directly
> or via one of its parent (Craig Russel)
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