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https://issues.apache.org/jira/browse/OPENJPA-2591?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14560197#comment-14560197
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Rick Curtis commented on OPENJPA-2591:
--------------------------------------
I haven't looked at the code for this problem, but I have a question in general
about DynamicDataStructs because I've never come across anyone using it in the
wild. Is it helpful for your application? If so, how much of a performance
improvement did you observe when it is enabled?
> Missing synchronisation when using "openjpa. DynamicDataStructs"
> -----------------------------------------------------------------
>
> Key: OPENJPA-2591
> URL: https://issues.apache.org/jira/browse/OPENJPA-2591
> Project: OpenJPA
> Issue Type: Bug
> Components: Enhance
> Affects Versions: 2.4.0
> Reporter: Philipp Marx
> Priority: Minor
>
> When using "DynamicDataStructs=true" there is a chance of running into an
> ClassFormatError due to multiple enhancing of persistent classes:
> java.lang.ClassFormatError: Duplicate field name&signature in class file
> <class-name-strippted>openjpapcdatadatacache
> at java.lang.ClassLoader.defineClass1(Native Method) ~[?:1.7.0_75]
> at java.lang.ClassLoader.defineClass(ClassLoader.java:800) ~[?:1.7.0_75]
> at java.lang.ClassLoader.defineClass(ClassLoader.java:643) ~[?:1.7.0_75]
> at serp.bytecode.BCClassLoader.findClass(BCClassLoader.java:50)
> ~[org.apache.servicemix.bundles.serp-1.15.1_1.jar:?]
> at java.lang.ClassLoader.loadClass(ClassLoader.java:425) ~[?:1.7.0_75]
> at java.lang.ClassLoader.loadClass(ClassLoader.java:358) ~[?:1.7.0_75]
> at java.lang.Class.forName0(Native Method) ~[?:1.7.0_75]
> at java.lang.Class.forName(Class.java:274) ~[?:1.7.0_75]
> at
> org.apache.openjpa.enhance.DynamicStorageGenerator.createFactory(DynamicStorageGenerator.java:169)
> ~[openjpa-2.4.0.jar:2.4.0]
> at
> org.apache.openjpa.enhance.DynamicStorageGenerator.generateStorage(DynamicStorageGenerator.java:124)
> ~[openjpa-2.4.0.jar:2.4.0]
> at
> org.apache.openjpa.enhance.PCDataGenerator.generateStorage(PCDataGenerator.java:115)
> ~[openjpa-2.4.0.jar:2.4.0]
> at
> org.apache.openjpa.enhance.PCDataGenerator.generatePCData(PCDataGenerator.java:92)
> ~[openjpa-2.4.0.jar:2.4.0]
> at
> org.apache.openjpa.datacache.DataCacheStoreManager.newPCData(DataCacheStoreManager.java:797)
> ~[openjpa-2.4.0.jar:2.4.0]
> at
> org.apache.openjpa.datacache.DataCacheStoreManager.updateCaches(DataCacheStoreManager.java:144)
> ~[openjpa-2.4.0.jar:2.4.0]
> at
> org.apache.openjpa.datacache.DataCacheStoreManager.commit(DataCacheStoreManager.java:87)
> ~[openjpa-2.4.0.jar:2.4.0]
> The issue happens if the enhancing hasn't been performed yet and multiple
> threads concurrently commit a transaction. They will both call
> PCDataGenerator#generateStorage with the same class. This should be guarded
> with some kind of synchronisation around the underlying map (containing the
> enhanced classes). It's hard to provide a test case for this but keeping a
> breakpoint open in #generateStorage and committing multiple threads will lead
> to the exception above.
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