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  1. OpenJPA
  2. OPENJPA-2222

Concurrency issue with JPA enhancement in Apache Open JPA



    • Type: Bug
    • Status: Open
    • Priority: Major
    • Resolution: Unresolved
    • Affects Version/s: 2.2.0
    • Fix Version/s: None
    • Component/s: Enhance
    • Labels:


      Working Jeremy Bauer, we discovered the following issue:

      I think I've figured out what is causing the transformer to return null in some (intermittent) cases. I'm seeing multiple threads [Blueprint Extender: # ] calling into the same PCClassFileTransformer. I've pasted the stack for thread 1 below. I saw an identical instance for a thread 3 - operating on a different persistent class at the same time. This resulted in one of the transforms (per transform method below) returned null.

      public byte[] transform(ClassLoader loader, String className,
      Class redef, ProtectionDomain domain, byte[] bytes)
      throws IllegalClassFormatException {
      if (loader == _tmpLoader)
      return null;

      // JDK bug – OPENJPA-1676
      if (className == null)

      { return null; }

      // prevent re-entrant calls, which can occur if the enhancing
      // loader is used to also load OpenJPA libraries; this is to prevent
      // recursive enhancement attempts for internal openjpa libraries
      if (_transforming)
      return null;

      _transforming = true;

      return transform0(className, redef, bytes);

      Since you use the same transformer on multiple threads we are hitting the condition where there is a transform in progress and you are trying to do another transform on a separate thread.

      I spent some time looking at the JPA spec to determine what it says about transformer concurrency and I can't find anything that says that you shouldn't be able to call a transformer in a concurrent manner, hence this defect.




            • Assignee:
              pradine Brian DePradine
            • Votes:
              4 Vote for this issue
              3 Start watching this issue


              • Created: