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  1. OpenJPA
  2. OPENJPA-258

MetaDataInheritanceComparator is not transitive; C > B > A > C leads to out-of-memory crash in PCEnhancer


    • Type: Bug
    • Status: Closed
    • Priority: Blocker
    • Resolution: Fixed
    • Affects Version/s: 0.9.6
    • Fix Version/s: 1.0.2, 1.1.0
    • Component/s: jpa
    • Labels:
    • Environment:
      Sun JDK 5, Sun JDK 6


      Comparisons done by MetaDataInheritanceComparator are not transitive. It is possible to have classes A, B, and C such that the comparator simultaneously reports that A > B, B > C, and C > A. Under certain unlucky conditions, this causes the SortedTree holding the metadata resolution buffer to become confused during Red-Black fix, such that it can retrieve a certain element, but not delete it. The "processed" list then grows until heap is exhausted.

      In the enclosed sample project,

      A < B by name
      B < C by assignable primary key field
      C < A by "levels" from base class (Object)

      If you import the enclosed eclipse project into an AspectJ-enabled eclipse, and refer the AspectJ compiler to an OpenJPA jar file, you'll get the following output:

      bug.B > bug.A
      bug.C > bug.B
      bug.A > bug.C
      Cycle detected:
      bug.A > bug.C > bug.B > bug.A

      The project will work outside of AspectJ, and will exhibit the out of memory condition described above.

      I acknowledge that the enclosed persistence.xml file is not kosher, in that it doesn't list all classes to be instrumented. My own project, affected by this bug, has a correct persistence.xml file. I had to work hard to contrive a simple example, as the order in which classes are buffered affects the appearance of the bug.

      There is no work-around that I know of. I don't believe that the comparator's semantics are well-defined.




            • Assignee:
              jdf@us.ibm.com Jonathan Feinberg
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