[jboss-jira] [JBoss JIRA] (DROOLS-4565) MVELDialectRuntimeData is not thread safe

[Timo Gutjahr (Jira)]

    [ https://issues.jboss.org/browse/DROOLS-4565?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13790033#comment-13790033 ] 

Timo Gutjahr commented on DROOLS-4565:
--------------------------------------

Hi, I'm afraid we don't have a reproducer. We found the problem in our integration tests. When analyzing the problem we compared a serialized broken KB with a working KB and found that the set in MVELDialectRuntimeData contains one less element. The missing element was a MVELObjectClassFieldReader. We could make this observation with 3 different KBs.  Whereby the problem occurs only very rarely.

> MVELDialectRuntimeData is not thread safe
> -----------------------------------------
>
>                 Key: DROOLS-4565
>                 URL: https://issues.jboss.org/browse/DROOLS-4565
>             Project: Drools
>          Issue Type: Bug
>          Components: core engine
>    Affects Versions: 7.16.0.Final
>         Environment: Java 11.0.2
> Different OS
>            Reporter: Timo Gutjahr
>            Assignee: Mario Fusco
>            Priority: Major
>         Attachments: ForkJoinPool-1-worker-1.txt, NPE.txt, main.txt
>
>
> MVELDialectRuntimeData#mvelReaders is accessed concurrently but is not thread safe due to the usage of a HashSet. This may cause lost updates. (See  [^ForkJoinPool-1-worker-1.txt] and  [^main.txt] )
> If this happens and the kie base is serialized and deserialized it results in a NullPointerException at runtime. (See  [^NPE.txt] )
> We observed that the entries in this Set (mvelReaders) are serialized and important for the deserialization step because they contain information about transient objects that have to be re-initialized after deserialization.
> While losing this information due to concurrent access does not cause problems during compilation, serialization and deserialization of a kie base, they may cause NullPointerExceptions at runtime when transient fields remain uninitialized.



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