[jboss-jira] [JBoss JIRA] Created: (JBAS-5880) Synchronization Problem in TxServerClientInterceptor

[Justin Bertram (JIRA)]

Synchronization Problem in TxServerClientInterceptor 
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                 Key: JBAS-5880
                 URL: https://jira.jboss.org/jira/browse/JBAS-5880
             Project: JBoss Application Server
          Issue Type: Bug
      Security Level: Public (Everyone can see)
          Components: IIOP service
    Affects Versions: JBossAS-4.2.2.GA
            Reporter: Justin Bertram
            Assignee: Stefan Guilhen
             Fix For: JBossAS-4.2.4.GA


We found a synchronization problem when starting JBoss under load. In class TxServerClientInterceptor method getEmptyPropagationContext a static member is initialized without being synchronized.

While one thread is still initializing the otid member in line 100, an other thread assigns a new object to the "current" member so that otid is null.

... BINGO

sniplet from TxServerClientInterceptor
090    static PropagationContext getEmptyPropagationContext()
091    {
092       if (emptyPC == null)
093       {
094          // According to the spec, this should all be ignored
095          // But we get NPEs if it doesn't contain some content
096          emptyPC = new PropagationContext();
097          emptyPC.parents = new TransIdentity[0];
098          emptyPC.current = new TransIdentity();
099          emptyPC.current.otid = new otid_t();
100          emptyPC.current.otid.formatID = 666;
101          emptyPC.current.otid.bqual_length = 1;
102          emptyPC.current.otid.tid = new byte[] { (byte) 1 };
103          emptyPC.implementation_specific_data = ORB.init().create_any();
104          emptyPC.implementation_specific_data.insert_boolean(false);
105       }
106       return emptyPC;

Note: Please keep in mind that synchronization is done only if the emtyPC object needs initialization:

   static PropagationContext getEmptyPropagationContext()
   {
      if (emptyPC == null)
      {
         syncronized(any){
           if (emptyPC == null)
           {
               tempEmptyPc = new PropagationContext();

               tempEmptyPC.parents = new ....

               // assign as late as possible
               emptyPC = tempEmptyPc;
           }
         }
      }
      return emptyPC;

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